US 3601900 A
Description (OCR text may contain errors)
United States Patent  Inven ors Mauri J. Erisman Primary Examiner-Carroll B. Dority, Jr.
Oak Park; Attorneys- F. W. Anderson and C. E. Tripp Leonard M. Kaczmarski, Chicago, Ill.; Wesley W. Coffin, deceased, late of El h t lll b B tt g lf i) I y e y B Coffin ABSTRACT: Metal scrap having water and cutting 011$ A I No 814 884 thereon is cleaned and dried by hot treated gas. The gas circus 27 1969 lates through a drying chamber containing the scrap and Pat med Au causes the water and cutting oils to evaporate into a vapor nee a oration which mixes with the drying gas. The resultant combustible g 1 San Jose 5 mixture is treated for recycling through the dryer by first b said a d aid Ka zmar ki passing it through a dry dust collector which removes practiy n s c s cally all of the solid particles which are unavoidably picked up by the gas as it comes in contact with the meta] scrapv The [5 METHOD AND APPARATUS FOR DRYING METAL combustible gas mixture is Ill-81:1 fed i010 a furnace where bLll SCRAP ners ignite the gas to render it inert and raise its temperature The resultant hot inert as is s lit into two streams, one stream 19 Claims, 7 Drawing Figs. g 4 Pi going directly to a blending chamber and the remaining  U.S. Cl 34/26, ream being directed into a quencher for cooling, Upon lea 5234/79, A ing the quencher it passes through a wet dust collector to [5 I] hit. Cl F261) 3/00 remove any remaining Solid particles that were not removed i  Field of Search 34/26, 30, the dry dust couector. The relatively CO0] gas leaving the wet 79; 134/2 25; 110/8 A dust collect is blended with the hot gas that went directly to the blending chamber from the furnace, and emerges as a gas  References cued having a temperature intermediate that of the separate UNITED STATES PATENTS streams. This blended gas stream is subsequently blown into 2,720,710 10/1955 Erisman 34/28 the dryer to clean more metal scrap and repeat an identical cy- 3,310,009 3/1967 Jacobs 110/8 A cle.
TO STACK WET COLLECTOR so i 50 f QUENCHER V FAN do BLENDING FAN CHAMBER FAN 3 FEED CHUTE a 84 EXHAUST lo HOOD 3O 1 a4 1': J DRY A .77.. cu. M COLLECTOR DRYER FAN 24 57 l l 3 S PATENTEU AUBB'I I971 3,601,900
SHEET 1 nr 5 TO s'mcw T'll i l WET COLLECTOR so--- i 69 2 1 4'1 :7 QUENCHER I V V FAN FUME BURNER I l I v I '10 1 BLENDING FAN CHAMBER FAN ea FEED CHUTE EXHAUST HOOD 30 no om! COLLECTOR DRYER 37 FAN H as INVENTORS.
MAURICE J. ERISMAN LEONARD M. KACZMARSKI WESLEY W. CDFFIN, DECEASED, BY BETTY B- COFFIN, EXECUTRIX.
BY 6 .6? W 2,
ATTORNEYS PATENTEI] M1831 um sum 2 UF 5 "mi all PATENTEDAUG31 new SHEET 3 BF 5 PATENTEU AUBS] IBTl sum u 0F 5 BACKGROUND OF THE INVENTION 1. Field of the Invention This invention is concerned with a method of cleaning metal scrap, such as chips, filings, turnings, and the like, which are produced in machinery operations, anddeals more particularlywith the removal of cutting oils and water from such metal scrap.
It has been common practice in the past to process the metal scrap that results from machining operations for recovery of the cutting oil. Because the value of such metal scrap was formerly very low, little attention was given to the deteriorating effect the various oil recovery processes had on such scrap or to the preparation of the scrap for reuse. Recently, however, the value of such metal scrap has risen to an extent which makes it increasingly important to develop an economical process for removing the cutting oil and water from the scrap to prepare the latter for reuse. Of course, oxidation of the metal should be held to a minimum to provide, a maximum recovery and to improve the quality of certain processed metals. Also, the combustible mixture that may be produced if the cutting oil vapors are permitted to mix with the proper amount of oxygen presents a difficult problem .in the prevention of fires and explosions in such metal scrap recovery operations.
2. Description ofthe Prior Art Prior art scrap metal drying devices are described in U.S. Pat. No. 2,720,710 issued to John L. Erisman on Oct. 18, 1955, and in U.S. Pat. No. 2,836,901 issued to H. W. Davis on June 3.1958. In the John L. Erisman method, a stream of hot inert gas passes through a metal scrap drying chamber causing the cutting oil and water on the metal scrap therein to evaporate into a vapor which is mixed with the stream of gas as it leaves the drying chamber. The resultant gas mixture is combustible and is split upon emergence from the drying chamber. A portion of the mixture is rendered inert in a fume burner and dispersed into the atmosphere, the remainder being directed into a hydrostatic precipitator unit where .it becomes more inert due to its mixture with steam vapors. This basically inert gas is then fed into a heater unit where it is mixed with fuel and combusted until it is inert and has the desired temperature for treatment of the metal scrap in the dryer. It is then directed into the dryer to repeat an identical cycle.
The Davis method is similar to the Erisman method except that the emerging gaseous mixture from the dryer is not immediately split. The entire mixture is directed into a hydrostatic precipitator and split after leaving the precipitator. A portion of the gas is fed into a fume burner and combusted until inert, whereupon it is disbursed into the atmosphere, and the remaining portion is fed into a heater unit where it is rendered inert and acquires the desired temperature for treating the metal scrap in the dryer where it is next directed.
SUMMARY OF THE INVENTION The present invention concerns itself with cleaning metal scrap, such as chips, filings, and turnings so that the same can be reused. The cleaning generally involves removing water or cutting oils from the scrap, but more particularly it involves passing hot gas around the scrap and evaporating the oils and water from their surfaces. The gas used to clean the scrap must be treated before it can be used again or disbursed into the atmosphere becauseafter the cleaning process, the gas is combustible due to the blending of the drying gas with the evaporating oil vapors from the metal scrap. The cleaning gas also unavoidably picks up and suspends minute solid particles which must be removed, for antiair-pollution purposes, before any portion of the gas can be dispersed into the atmosphere. The method of the present invention effectively treats the cleaning gas to prepare it for recycling and reuse as well as for disbursement into the atmosphere, by removing the suspended solid particles, reheating the gas, and rendering it inert.
More specifically, the metal scrap is passed through a drying chamber where circulating hot inert gas effects an evaporation of the water and cutting oils from the scrap. At the terminus of the dryer, the cleaned metal scrap is separated from the resultant combustible gaseous mixture of oil vapors and the original drying gas. The gaseous mixture is directed through a dry dust collector. that almost entirely removes any minute solid particles that were unavoidably picked up by the gas during the cleaning process. The gaseous mixture, substantially free of any solid particles, is then guided into a furnace where burners ignite the mixture causing it to burn and thereby render the mixture inert while heating it to a predetermined temperature.
The inert gas leavingthe furnace is. split into two streams. The first stream of relatively high temperature gas passes directly into a blending chamber where it will subsequently reunite with the second stream. The second stream passes into a quencher wherein water sprays serve to lower its tempera ture ina direct heat transfer situation. The emerging relatively low temperature gas then enters a wet dust collector that removes any remaining solid particles that may be in the gas stream. Part of the relatively low temperature gas stream coming out of the wetdust collector is blown into the atmosphere by an exhaust fan but the other part is directed into the blending chamber to reunite with the first stream of relatively high temperature gas that passed directly to the blending chamber from the furnace. A temperature control device regulates the intake of the high and low temperature gases into the blending chamber so that the resultant gas emerging therefrom will be at the desired temperature for reuse in the drying chamber. Two inlet fans direct the hot inert gas from the blending chamber into the dryer. where it again serves to clean metal scrap and begin an identical cycle.
Accordingly, it is a primary object of the invention to provide an improved method of cleaning metal scrap without causing oxidation of the scrap.
Another object is to provide a method of removing volatile wetting liquids from metal scrap in such a manner as to prevent ignition of the liquid vapors.
Another object is to provide a method of cleaning volatile wetting liquids from metal scrap with hot inert gas so that the metal scrap is not oxidized and the volatile vapors are not ignited.
Still another object is to provide a method of treating combustible gas, which contains volatile vapors from wetting liquids on metal scrap, so that the gas can be reused in an inert state.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of the system showing the flow of the metal scrap and the gas in solid lines and the flow of gas in an alternative embodiment in dotted lines.
FIG. 2 is a front elevational view of the apparatus used in carrying out the method of the invention.
FIG. 3 is a plan view of the apparatus used in carrying out the method of the invention.
FIG. 4 is a sectional view taken on line 4-4 of FIG. 3 to show the part of the apparatus that is partially hidden in FIG.
FIG. 5 is an enlarged elevated view of the dry dust collector used to remove solid particles from the stream of gas.
FIG. 6 is a section through the quencher used to cool the gas.
FIG. 7 is an enlarged perspective view of the wet dust collector used to remove solid particles from the stream of gas.
I DESCRIPTION OF THE PREFERRED EMBODIMENT An understanding of the present invention is facilitated by reference first to FIG. 1 of the drawings wherein a schematic diagram of the metal scrap drying system is shown. The solid directional lines show the path of travel of the scrap metal and cleaning gas, while the dotted directional line shows'an alternate path for the cleaning gas in an alternative embodiment.
Beginning at the lower left-hand corner of the diagram, metal scrap having water and cutting oils thereon is placed in the feed chute 22. for introduction into a rotary dryer 10. Hot inert gas is fed into the dryer at l l to dry the scrap and remove the cutting oils from its surface. The scrap is discharged from the dryer at its opposite end into an exhaust hood 24 where it drops downwardly through discharge chute 26 for removal from the system. The gas which emerges from the opposite end of the dryer is combustible due to the evaporated oils from the metal scrap and is directed upwardly through the exhaust hood-24 into a dry dust collector 30 where any remaining solids that may have been entrained by the cleaning gas are removed. The combustible gas is drawn out of the dry collector 30 by an exhaust fan 41 and introduced into a fume burner 40 where the gas'is ignited and rendered inert. Upon emergence from the fume burner 40 the gas is split into two streams, one stream going in its very hot state directly to a blending chamber 70 and the other stream passing through a quencher 50 where it is cooled. After the second stream leaves the quencher it can be directed into a wet dust collector 60, before passing to the blending chamber, to remove any remaining solids in the gas, or it can bypass the wet collector in an alternative embodiment as shown by dotted lines, and pass directly into the blending chamber for reunion with the first stream. In either embodiment, part of the second stream is directed to an exhaust stack for disbursement into the atmosphere. The portion of the second stream which passes into the blending chamber 70 is relatively cool compared to the hot first stream and their reunion in the blending chamber results in an emerging unified gas stream having a temperature intermediate that of the first and second streams. This emergent inert gas is blown back into the dryer 10 for reuse as a cleaning agent.
The dryer 10, as best illustrated in FIGS. 2 and 3, is a horizontally arranged rotatable dryer of the type described in the John L. Erisman U.S. Pat. No. 2,522,025, dated Sept. 12,
1950 for Rotary Dryer or Cooler. This dryer 10 has positioned within its outer cylindrical housing an internal material supporting shell formed of a plurality of tangentially arranged, longitudinally extending louvers between which the drying gas passes for delivery to the bottom of the bed of material advancing longitudinally through the dryer.
The dryer housing is supported for rotation about a horizontal axis by trunnions l2 and is driven by a motor 14 through a speed reducing unit 16 which drives the pinion'gear 18 that is in engagement with a ring gear 20 extending around the dryer. The material to be dried and cleaned is introduced into the dryer 10 through the feed chute 22 at one end of the dryer. Material is discharged from the dryer 10 at the opposite end into the exhaust hood 24 where it drops downwardly through the discharge chute 26 onto a conveyor 27 or any other suitable means for transferring the cleaned scrap from the apparatus. The feed chute 22 and discharge chute 26 may take the form of a rotary gate feeder, or any other conventional device which will permit movement of material therethrough while preventing the escape of the drying gas.
The drying gas which is discharged from the dryer 10 passes through the exhaust hood 24 and necessarily entrains a limited quantity of solid particles therealong. This gas is directed by duct 28 into the dry dust collector 30 where the solid particles are removed from the gas to prevent a clogging of the duct work and to prevent air pollution when a portion of the gas is later released into the atmosphere, as will be discussed below.
The dry dust collector 30 consists of a plurality of tubular members having inlet tubes 34 and outlet tubes 36 as shown in FIG. 5. The solid-laden gas enters the dry collector horizontally by means of duct 28 and opening 32. It is channelled by the pitch of the roof of the collector into inlet tubes 34 and passes through the helical spinner vanes 38 at the top of the inlet tubes. It is thereby forced into a spinning action which exerts centrifugal force on the solid particles. The centrifugal force, combined with natural gravitational forces, holds the solids against the internal surface of the inlet tube as it spins them downwardly and completes the separation of entrained solids from'the gas. As a result of the cyclonic action, a vortex is formed in the area 39 immediately below the lower end of the outlet tube 36. This action draws the cleaned gas upward through the centered outlet tube while the solids continue downward into the hopper bottom 37 and pass through a discharge chute 35 onto conveyor 27 for transfer from the apparatus. The dry collector is a commercially available item marketed under the designation Series 348 Dust Collector by American Standard of Detroit, Mich.
The cleaned but still combustible gas is drawn from the dry collector 30 by an exhaust fan 41 and introduced into the bottom of a fume burner 40 through conduit 43.
The fume burner 40, best seen in FIG. 4, is a vertically arranged cylindrical furnace which functions to burn the drying gas and thereby render it inert while simultaneously raising its temperature. Disposed on opposite sides of the fume burner near the bottom where the combustible gas is introduced into the burner, are two gas burners 42 which serve to ignite the drying gas as it enters the fume burner 40. Two air inlet hoses 44 are mounted on the fume burner 40 adjacent the gas burners 42 to provide additional oxygen for adequate burning of the gas. The air inlet hoses 44 have their opposite ends connected to a header'45 which links the hoses to a fan 46 for delivering air under pressure. The drying gas burns in the fume burner 40 and emerges from the top thereof as a hot inert gas of approximately 1500 F.
The hot inert gas emerging from the fume burner 40 is split at junction 47. Part of the gas passes through conduit 49 directly to the blending chamber 70, which will be described in more detail below, and the remainder of the gas enters'the quencher 50 shown in FIG. 6.
The quencher 50 is a heat reducing unit and serves to cool the hot gas down to approximately 193 F. by spraying relatively coolwater through the gas. A header 52 connected to a water supply, not shown, has nozzles 54 distributed along its length to spray the water uniformly through the gas. At 193 F. the resultant water vapor in the quencher, created by the mixing hot gas and cool water, will blend with the stream of gas to dilute the oxygen content of the stream.
The gas leaves the quencher 50 through duct 56. A bleed off conduit 58, connected to the duct 56, provides a dual passage for the gas so that part can be dispersed into the atmosphere via a stackconduit 59 to which the opposite end of conduit 58 is connected. The remainder of the gas leaving the quencher is passed through a wet dust collector 60 where any remaining sold particles suspended in the gas are removed.
The wet collector 60 comprises a plurality of tubular structures 62, as shown in FIG. 7, each having an inlet cone 64, a barrel 66, and an outlet cone 68. The inlet cone 64 has two tangential inlets 64a into which the gas with the suspended solids therein enters. The inlet cones 64 of the tubular structures 62 are disposed in an upper chamber 61 of the wet collector 60 so that all of the entering gas must enter one of the inlet cones. Water is introduced into the incoming gas in this upper chamber 61 so that when the gas enters one of the inlet cones and is spun downwardly, the solid particles suspended in the gas impinge the wetted peripheral surface of the inlet cone and subsequently the barrel 66, thereby passing the outside of outlet cone 68 (shown by dotted arrows in FIG. 7) into a second intermediate chamber 63 of the wet collector 60. The solid laden slurry in this intermediate chamber is then discharged through drains in the wall. As the solid articles are thrown against the wetted peripheral surfaces of the inlet cone and barrel for removal into the intermediate chamber 63, clean gas passes through the center of the barrel and into a third lower chamber 65 through the center of the outlet cone 68 whose open lower end is exposed to the lower chamber. There is a large outlet 65a in the lower chamber 65 through which the cleaned gas can be drawn from the wet collector 60 and into a conduit 69a by an exhaust and stack fan 69. The wet collector above described is a commercially available item marketed under the designation Type R Rotor-Clone Wet Centrifugal Dust Collector by American Air Filter Co., Inc. of 5 Louisville, Ky.
The fan 69 directs the gas upwardly into a duct 67 where the gas is again split, part being passed into the atmosphere through stack conduit 59 and the remainder passing through conduit 71 to the blending chamber'70.
The wet collector 60 and exhaust fan 69 may be bypassed (dotted lines in FIG. 1) if the gas is not carrying a sufficient quantity of solid particles to warrant further solid removal. It has been found when cleaning certain scrap that the dry dust collector 30 removes virtually all of the solid matter entrained by the gas as it leaves the dryer 10. In this case it is not neces sary to pass the gas through a wet collector, whose only purpose is to remove remaining solid particles in the gas. There fore, it is within the spirit of this invention to provide a metal scrap cleaning and drying system wherein a wet collector is not used. This, of course, lowers the operating expense of the system. In such a system the gas leaving the quencher is drawn out by an exhaust fan 73 (FIG. 1) and blown directly into the blending chamber 70.
In either embodiment, with or without the wet collector 60, the gas which has been cooled in the quencher 50 to a temperature of approximately 193 F. is directed into the blending. chamber 70 for reunification with the hot (approximately 1500 F.) inert gas that passed directly from the fume burner 40 to the blending chamber.
The blending chamber 70 is a vertically disposed cylindricaltank having a hollow interior except for oppositely disposed baffles mounted to effect a consistent mixture of the respective hot and relatively cool streams of gas. Adjacent the intake ports for the hot and relative cool gases respectively are conventional temperature control devices to regulate the intake of the respective gases so that the gas emitted from the blending chamber 70 has a uniform temperature of approximately 740 F.
The gas emitted from the blending chamber 70 is blown by two inlet fans 76 and 77 via conduit 78 back into the dryer for reuse as a drying and cleaning agent.
To prevent pressure buildup and possible explosion within the dryer 10, there are provided two bleedoff lines 81 and 82.
which are linked to a fan 84, situated on top of the blending chamber for convenience, to blow the released gas through heated in the fume burner to a temperature of 1500 F. for air pollution reasons since part of the gas is exhausted into the atmosphere. Air pollution experts have determined that a temperature of l400 F. is required to remove fume and hydrocarbon odors which pollute the air.
As an additional precaution to prevent the possibility of an explosion in the dryer 10, the inlet to the dryer is equipped with an oxygen meter so that a maximum of 10 percent oxygen is never exceeded. The oxygen content of the drying gas is controlled at the fume burner and is regulated so that sufficient oxygen is provided for complete combustion of the gas therein. However, the oxygen content of the gas passing into the dryer 10 is held below 10 percent and thus below that which could support combustion of the evaporated cutting oils in the dryer.
Since the particles size and characteristics of the metal scrap to be treated, the amount of oxidation of the treated scrap that will be permitted, and the amount and type of liquid with which the untreated scrap is wetted may vary greatly for each installation, the apparatus that is employed for carrying out the method must be capable of performing under a wide range of operating conditions. The required variations in operating conditions are provided by controlling the heat sup plied to the material by the drying gas passing through the dryer 10 and by varying the rate of feed of the material into the feed chute 22.
Considering first the control of the heat supplied by the drying gases and the inherent limitations of the apparatus by which the method is carried out, it will be readily apparent that the heat supplied may be controlled by varying the temperature of the gas entering the dryer 10. The temperature, of course, must exceed the minimum value which will effect evaporation of the particular mixture of cutting oil and water carried by the metal scrap and must not approach too closely the temperature at which the scrap would be oxidized to an objectionable extent; that is, to an extent which would substantially reduce the value of the scrap for subsequent use.
The supply of heat may also be controlled by regulating the volume of the drying gases. In this connection, it will be noted thatthe dryer 10 is equipped with controls for varying the amount of drying gases flowing through the bed of metal scrap so that the volume of gas flowing through the bed is progressively reduced as the material is dried during its movement toward the discharge end of the dryer.
The maximum permissible temperature of the drying gas flowing through the dryer at a given rate, therefore, will depend for the most part upon the type of metal scrap which is being treated. In other words, steel scrap may be subjected to temperatures much higher than aluminum or copper. As a further consideration in determining the maximum temperature to which the particles may be subjected, it will be noted that upon removal of the particles from the dryer 10 through the discharge chute 26, the oxidation of the metal in the presence of air will be accelerated as the discharge temperature of the metal is increased.
Further variation of the operating conditions quite obviously can be provided by changing the rate at which the wetted material is introduced to the dryer and the length of time the material is exposed to the drying gas.
It is apparent from the above description that the present invention involves a metal scrap cleaning method and apparatus which requires only one heating unit. Therefore, the cost of maintenance and the fuel expense is kept to a minimum. It is apparent also that due to the small amount of fuel required in the system, only a small amount of oxygen is put into the system through the fuel burner. This provides for a safer operation by preventing the possibility of explosions in the dryer.
Although the best mode contemplated for carrying out the present invention has been herein shown and described, it will be apparent that modification and variation may be made without departing from what is regarded to be the subject matter of the invention.
What is claimed is: i
1. A method of removing cutting oils and the like from metal scrap that is wetted therewith comprising the steps of flowing a stream of gasthrough a substantially closed path, passing the said stream of gas in a preheated and inert state through a zone in said path having a bed of said metal scrap to evaporate the wetting liquid and entrain the resulting volatile vapor in the flowing stream of gas, passing the resultant combustible stream of gas through a fume burner wherein the said combustible gas is burned to raise the temperature of the gas to at least l400 F. and render the gas inert, then dispersing a portion of the inert gas into the atmosphere and cooling the remaining portion down to approximately 740 F. before passing it through an identical cycle.
2. A method of removing cutting oils and the like from metal scrap that is wetted therewith comprising the steps of flowinga stream ofgas through a substantially closed path, passing the said stream of gas in a preheated and inert state through a zone in said path having a bed of said metal scrap to evaporate the wetting liquid and entrain the resulting volatile vapor in the flowing stream of gas, passing the resultant combustible stream of gas through a fume burner wherein the said combustible gas is burned to raise the temperature of the gas and render the gas inert, splitting the stream of gas so that a removing means before burning the gas in the said fume burner.
4. The method of claim 3 further including the step of passing the said second part of the said stream of gas through an additional solid particle removing means, before reuniting said second part with said first part in said blending chamber.
5. The method of claim 3 further including the step of releasing a portion of said second part of said stream of gas to the atmosphere after the second part of the said stream of gas has passedthrough the said heat reducing unit.
6. The method of claim 4 further including the'step of releasing a portion of said second part of said stream of gas to the atmosphere after the second part of the said stream of gas has passed through the said additional solid particle removing means.
7. The method of claim 6 further including the step of placing a first fan in the said closed path to help draw the said stream of gas out of the said first solid particle removing means and blow it into the said fume burner.
8. The method of claim 7 further including the step of placing at least one additional fan in the said closed path to help draw gas out of the said blending chamber and blow it into the said dryer.
9. The method of claim 8 further including the step of dispersing a part of the said second part of the said stream of gas into the atmosphere after the said second part has passed though the said heat reducing unit.
10. The method of claim 4 further including the step of individually regulating the intake into the said blending chamber of the said first and second parts of the said stream of gas so as to control the temperature of the stream of gas leaving the said blending chamber.
ll. The method of claim 9 wherein the said combustible stream of gas burned in the said fume burner is heated to a temperature of 1500 F.
12. The method of claim 11 wherein the said second part of the said stream of gas is cooled down by the said heat reducing unit to a temperature of about 193 F. at which temperature the resulting water vapor will blend with the said second part of the said stream of gas.
13. The method of claim 12 further including the step ofindividually regulating the intake into the said blending chamber of the said first and second parts of the said stream of gas so that the temperature of the stream of gas leaving the said blending chamber is about 740 F.
14. An apparatus for removing cutting oils and the like from metal scrap that is wetted therewith comprising in combination dryer means in which a stream of inert gas is passed through a bed of said metal scrap to evaporate the wetting liquid therefrom and wherein the resulting volatile vapor is entrained in the stream of gas, fume burner means connected to the said dryer means to burn the resultant combustible stream of gas emerging from the dryer means to render it inert and raise its temperature above l400 F., means for dividing the stream of gas after it has passed through the said fume burner means so that a portion of the stream of gas can be dispersed into the atmosphere, and heat reducing means for reducing the temperature of the gas which is not dispersed into the atmosphere so that it can be directed back into the said dryer means.
15. An apparatus for removing cutting oils and the like from metal scrap that is wetted therewith comprising in combination dryer means in which a stream of inert gas is passed through a bed of said metal scrap to evaporate the wetting liquid therefrom and wherein the resulting volatile vapor is entrained in the stream of gas, fume burner means connected to the said dryer means to burn the resultant combustible stream of gas emerging from the dryer means to render it inert and raise its temperature above l400 F., first dividing means for dividing the stream of gas into two portions, heat reducing means for reducing the temperature of the first of said two portions, second dividing means for dividing the portion'of gas leaving the said heat reducing means into two or more portions so that the first of these two more portions can be dispersed into the atmosphere and the second of these two more portions can be united with the second portion leaving the said first dividing means, and blending means for uniting the second portion leaving the said first dividing means with the second portion leaving the said second dividing means so that the two portions of relatively hot and cool gases respectively are suitable for recycling through the said apparatus.
16. The apparatus of claim 15 further including a first solid particle removing means disposed between and connected to the said dryer means and the said fume burner means, to remove any solid particles that may have been picked up by the said stream of gas as it passed through the said bed of metal scrap in the dryer means.
' 17. The apparatus of claim 16 further including a second solid particle removing means disposed so that the second portion of the gas leaving the said second dividing means will pass therethrough to remove any solid particles remaining in the gas before the said second portion of the gas leaving the said second dividing means enters the said blending means.
18. The apparatus of claim 17 further including a first fan means to help draw the said gas out of the said first solid particle removing means and blow the gas into the said fume burner means.
19. The apparatus of claim 18 further including a second fan means to draw the gas out of the said blending means and blow it into the said dryer means.