Abstract:
Described is an apparatus  10  and process of filtering metal working fluid containing metal fines comprising: providing a metal working fluid containing metal fines therein  12  wherein the fluid is generated in the working of a metallic member and wherein optionally a substantial portion of the fines is less than about 50 microns in diameter; passing  14  the fluid with fines therein to a cyclone separator  16 ; recycling  18  a portion of the fluid passing from a first exit  20  of the cyclone separator so that it can be used as a fluid in the metal working process; and collecting  36  a portion of the fines exiting from the cyclone separator.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention pertains to the use of cyclone separators to separate fluid from particulates contained in the fluid and in particular to the treatment of solutions generated in the metal working field so that the fluid may be reused or recycled to the metal working process.  
       BACKGROUND OF THE INVENTION  
       [0002]     In the metal working field coolants are applied to a substrate during a metal working process such as grinding or machining. The coolant as it leaves the substrate will therefore contain metal fines from the metal working process. In order to re-utilize the coolant, it becomes necessary to filter the coolant to separate the metal fines.  
         [0003]     In the metal working field, coolants are applied to a substrate during a metal working process such as grinding or machining. The coolant as it leaves the substrate will therefore contain metal fines from the metal working process. In order reutilize the coolant it becomes necessary to filter the coolant to separate the metal fines. During the course of the metal working process, the filter media will need to be changed to ensure a sufficient efficiency and a high quality filtering process. The filter media has a tendency to be clogged with the metal fines. At the same time, the filter media has contained in it the metal working coolant as well as oil and grease that would be associated with the machines under the metal working conditions.  
         [0004]     There is a desire to decrease the amount of undesirable effluent in the metal working industry as well as soiled filter media generated in the metal working industry. Because the end product contains substances which must be handled in an environmentally safe manner, the soiled products accordingly are a costly material to be disposed of in a safe manner. 
     
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0005]     These and other objects, features and advantages of the present invention will be apparent from the following detailed description of the preferred forms and best mode, appended claims, and accompanying drawings in which:  
         [0006]      FIG. 1  is a schematic diagram describing an embodiment of the invention herein. 
     
    
     BRIEF SUMMARY OF THE INVENTION  
       [0007]     Described is a process of filtering metal working fluid containing metal fines comprising: providing a metal working fluid containing metal fines therein wherein the fluid is generated in the working of a metallic member and wherein a substantial portion of the fines is less than about 50 microns in diameter; initially passing the fluid with fines therein to a cyclone separator; recycling a portion of the fluid passing from a first exit of the cyclone separator so that it can be used as a fluid in the metal working process; and collecting a portion of the fines exiting from the cyclone separator.  
         [0008]     Another embodiment is a process of filtering metal working fluid containing metal fines comprising: providing metal working fluid containing metal fines therein wherein the fluid is generated in the working of a metallic member and wherein a substantial portion of the fines is less than about 50 microns in diameter; passing the fluid with fines therein to a cyclone separator; recycling a portion of the fluid passing from a first exit of the cyclone separator so that it can be used as a fluid in the metal working process; passing a mixture of fluid and fines exiting from the cyclone separator to a settling tank wherein a portion of the fines settles in the tank and recycling a portion of the fluid from the settling tank so that it can be used as a fluid in the metal working process; passing a portion of fluid containing fines exiting from the cyclone separator to a magnetic separator; recycling a portion of the fluid passing from a first exit of the magnetic separator so that it can be used as a fluid in the metal working process; and collecting a portion of the fines from the magnetic separator.  
         [0009]     Another embodiment is a process of filtering metal working fluid containing metal fines comprising: providing a metal working fluid containing metal fines therein wherein the fluid is generated in the working of a metallic member; passing the fluid with fines therein to a cyclone separator, thereby partially separating a portion of the fluid from the fines; passing a mixture of fluid and fines exiting from the cyclone separator to a settling tank wherein a portion of the fines settles in the tank; passing a portion of fluid containing fines exiting from the settling tank to a magnetic separator; separating a portion of the fines from the fluid in the magnetic separator; and collecting a portion of the fines from the magnetic separator.  
         [0010]     Another embodiment is a process of filtering metal working fluid containing metal fines comprising: providing a metal working fluid containing metal fines therein wherein the fluid is generated in the working of a metallic member and wherein a substantial portion of the fines is less than about 50 microns in diameter; passing the fluid with fines therein to a cyclone separator; wherein the pressure of the fluid, in pounds per square inch gauge (psig), has a numeric ratio with the flow rate of the fluid, in gallons per minute (gpm), into the separator wherein the psig number is at least 60% of the gpm flow rate number; recycling a portion of the fluid passing from a first exit of the cyclone separator so that it can be used as a fluid in the metal working process; and collecting a portion of the fines exiting from the cyclone separator.  
         [0011]     Another embodiment is an apparatus for separating fines from a metal working fluid containing metal fines comprising: a conduit for supplying a metal working fluid containing metal fines therein to a cyclone separator from a source of the metal working fluid containing metal fines, which separator separates a portion of the fluid from the fines, wherein a substantial portion of the fines is less than about 50 microns in diameter; a first exit conduit from the cyclone separator for recycling a portion of the fluid passing from the first exit of the cyclone separator to a vessel so that it can be retained therein and used as a fluid in a metal working process; and a second exit conduit from the cyclone separator for collecting a portion of the fines exiting from the cyclone separator.  
         [0012]     Another embodiment is an apparatus for separating fines from a metal working fluid containing metal fines comprising: a conduit for supplying a metal working fluid containing metal fines therein to a cyclone separator from a source of the metal working fluid containing metal fines, which separator separates a portion of the fluid from the fines, wherein a substantial portion of the fines is less than about 50 microns in diameter; a first exit conduit from the cyclone separator for recycling a portion of the fluid passing from the first exit of the cyclone separator to a vessel so that it can be retained therein and used as a fluid in a metal working process; a second exit conduit from the cyclone separator; a settling tank for receiving a mixture of fluid and fines exiting from the second exit conduit of the cyclone separator wherein a portion of the fines settles in the tank and a settling tank conduit for recycling a portion of the fluid from the settling tank so that it can be used as a fluid in the metal working process; and a magnetic separator wherein a portion of fluid containing fines exiting from the second exit of the cyclone separator is passed via a conduit to the magnetic separator; a first exit conduit of the magnetic separator through which a portion of the fluid passing from the first exit of the magnetic separator is recycled so that it can be used as a fluid in the metal working process; and a second exit of the magnetic separator through which a portion of the fines from the magnetic separator are collected.  
         [0013]     Another embodiment is an apparatus for separating fines from a metal working fluid containing metal fines comprising: a conduit for supplying a metal working fluid containing metal fines therein to a cyclone separator from a source of the metal working fluid containing metal fines, which separator separates a portion of the fluid from the fines; an exit conduit from the cyclone separator; a settling tank for receiving a mixture of fluid and fines exiting through the exit conduit of the cyclone separator wherein a portion of the fines settles in the tank; an exit conduit from the settling tank; a magnetic separator wherein a portion of fluid containing fines exiting from the exit conduit of the settling tank is passed via the exit conduit of the settling tank to the magnetic separator; and an exit of the magnetic separator through which a portion of the fines from the magnetic separator are collected.  
       DETAILED DESCRIPTION OF THE INVENTION  
       [0014]     Definitions.  
         [0015]     Metal Working Fluid means the fluid used during the metal working process to cool the substrate and remove debris during the metal working process. A wide variety of metal working operations are utilized such as rolling, washing, grinding, honing and the like. The metal generated from metal working includes aluminum, chrome, steel, iron based materials, stainless steel and the like.  
         [0016]     Metal Fines means the small particles that are produced in the metal working process and need to be filtered in order to recycle and reuse the metal working fluids.  
         [0017]     Treating means to subject to a process, an action or a change to the process or the material passing through the steps of a process.  
         [0018]     The singular forms “a” or “an” or “the” include plural references unless the context clearly indicates otherwise.  
         [0019]     In the metal working industry very fine particulate material is generated during the course of the metal working. Listed below in Table 1 is a breakdown of particle size in a sample of metal working liquid.  
                                             TABLE 1                                   Size               (microns)   Particle Counts/ml                                        &gt;100   μm   10           50-100   μm   70           25-50   μm   401           20-25   μm   360           15-20   μm   951           10-15   μm   3,416           5-10   μm   16,031           2-5   μm   48,489                      
 
         [0020]     Turning now to the process utilized in the present invention reference may be made to  FIG. 1  wherein an embodiment process  10  for filtering metal working fluid containing metal fines  10  is shown. From a source (not shown) the metal working fluid or machining liquid and particles may be stored or may be sent directly to the treatment process for filtering and separating fluid from metal fines. The source of the machining liquid and particles  12  is fed via conduit  14  to a cyclone separator  16 . In general, a cyclone separator is a device that is conical shape where the fluid, and metal fines that are suspended therein, are passed, generally tangentially, into the upper portion of the cyclone separator and circulate through the device with a majority of the liquid going out the top of the device via conduit  18  after being circulated through the separator and a more concentrated amount of liquid and particles exiting from the bottom, schematically shown as conduit  20  from the cyclone separator. It is to be appreciated that the concentration of metal fines in the machining liquid in vessel  10  may typically be from about 100 to 1000 parts per million (ppm) in the liquid. After passing through the cyclone separator, the amount of particles in fluid exiting through conduit  20  would be substantially increased, generally from about 2 to 10 times the product feed to the cyclone separator in step  16 , more preferably about 6 to 8 times in increased ppm in the liquid i.e., about 1500-20,000 ppm.  
         [0021]     The liquid exiting the cyclone separator at the top exits via conduit  18  for being recycled to be used in a metal working process.  
         [0022]     After the liquid and particles exit the cyclone separator at conduit  20  they then may be passed into a settling tank  22 . There, the particles settle by gravity, generally to the bottom of the tank, from which they may be removed through conduit  24 . The liquid may be decanted through conduit  26  and recycled so that it may be used further in metal working process.  
         [0023]     Frequently the liquid flow rates through the magnetic separator are substantially lower than through the cyclone separator, generally about 1 to 5 gallons per square foot of magnetic separator area per minute.  
         [0024]     After the liquid and fines exit through the bottom of the settling tank such as through conduit  24 , the mixture is directed towards a magnetic separator  28 . There, due to the magnetic attraction to the metals, the material is subjected to further separation. The liquid exiting from the metal separator may be recycled through conduit  32 . The materials exiting the magnetic separator may be substantially high in concentration of the fines. The metal may be subjected to a further filtration process using normally commercially available filtering media at reference point  34 . The liquid exiting such filtration may likewise be recycled through conduit  36  and the filtering media subsequently disposed of.  
         [0025]     Alternatively, the liquid in increased particle amount is the liquid may pass via conduit  17  directly to the filtration step  34 .  
         [0026]     Alternatively, the liquid plus increased amount of particles may exit via conduit  19 , by-pass the settling tank and go directly to the magnetic separator.  
         [0027]     It is to be appreciated that the rate of fluid going through the cyclone separator can vary substantially, such from 50 to 500 gallons per minute, more preferably 50 to 300 gallons per minute (gpm). Due to substantial separation of fluid, the concentration of the amount of fines exiting the filtering process  10 , the particles coming out of the magnetic separator may be substantially concentrated so that they could be used for subsequent metal recovery. In other words, the particles may be of a sufficient dry nature that they can be recycled in normal metal regeneration techniques such as powdered metallurgy and the like.  
         [0028]     It is also to be appreciated that the overall flow of liquid plus particles through process  10  can be substantially increased up to about 3500 gpm. In such high flow rates, multiple separators may be used in the cyclone separator step.  
         [0029]     It is also to be appreciated that the liquid need not be recycled with each and every step as shown in the overall process  10  of  FIG. 1 .  
         [0030]     In the past, it has been found that cyclone separators are not effective in removing small particulate from liquids. While applicant does not wish to be bound to any particular theory, it is believed that the flow of the liquid and particulate through the cyclone should be at a sufficient inlet pressure to obtain desirable removal of the small particles. It has been found that when the inlet pressure (pounds per square in gauge)(psig) number has a ratio at least 60% of the flow rate number through the cyclone separator (in gallons per minute) then the overall process described herein can operate in an improved efficient manner. It is believed, that the particles effectively are agglomerated in the overall process which facilitates collecting a portion of the agglomerated metal fines concentrated in a reduced volume of fluid exiting from the cyclone separator via exit conduit  20  or exit conduit  19 . For example, it has been found desirable to have an inlet of pressure into a cyclone separator of about 50 to 80 psig while the fluid rate permitted is approximately 60 to 100 gpm preferably 65 to 70 gpm, i.e., a numeric ratio of about 80% (inlet pressure number:inlet flow number).  
         [0031]     The filter media that may be utilized at the end of the process at reference numeral  34  can be described as follows: a type that is supported across a fluid flow passage for collecting particulate out of the fluid and subsequently being moved out of the flow passage after being congested with particulate. The filter media can make up a wide variety of materials, preferably thermoplastic materials such as polyolefins, such as polypropylene, polyethylene, TPO, nylon, polyester, PET (polyethylene-terephthalate), and the like and mixtures thereof. Some filter media that may be utilized are Cerex, trademark of Cerex Corporation, Pensicola, Fla. for spun bonded nylon 6.6. Other filter media include CoClean, trademark of Crystal Filtration of Rochester Hills, Mich. which is a mixture of microfibers such as a blend of polypropylene, cellulose, and polyester microfibers. The filters may be reinforced with polypropylene spun bonded for strength. Other filter media includes Kiara, trademark of Polymer Group for thermally bonded nonwoven material made from polyester fabrics coated with polyethylene. Other filter media includes Microclean, trademark of Crystal Filtration for polypropylene microfibers sandwiched between layers of spun bonded polypropylene. Other filter media may be spun bonded polyester, polypropylene and the like. Other filter media includes Powerloft, a trademark of Kimberly Clark for fibrous web material or alternatively rayon and the like. Other filter media may be Ultraloft, a trademark of Polymer Group for carded thermally bonded bi-component media. Other filter media may be Reemay, a trademark of BBA for spunbond polyester. Other filter media may be Masterflow, a trademark of BBA for a polyester filter media. Other media may be Holliflow, a trademark of Filtration Systems Products for a polyester filter media. Other media may be ATM, a trademark of Flo-Tec for layered and ultrasonically bonded filter media. Other media may be EnviroClean, a trademark of Crystal Filtration for polyester filter media made from recycled beverage bottles. Other filter media that may be utilized in the present invention is that described in U.S. Pat. Nos. 2,925,560 and 5,714,067 hereby incorporated by reference.  
         [0032]     Cyclone separators are commercially available from a wide variety of sources including Deister Products &amp; Machine Company, Knoxville, Tenn., Elastech of Humble, Tex. or Vortex Ventures of Houston, Tex.  
         [0033]     Magnetic separators are likewise well known and can be ceramic or nickel magnets or rare earth magnets such as those containing neodymium. One supplier of such magnets is Eriez of Erie Pa. See for example U.S. Pat. No. 6,149,014 hereby incorporated by reference  
         [0034]     While the forms of the invention herein disclosed constitute presently preferred embodiments, many others are possible. It is not intended herein to mention all of the possible equivalent forms or ramifications of the invention. It is understood that the terms used herein are merely descriptive rather than limiting, and that various changes may be made without departing from the spirit or scope of the invention.