US3846173A

US3846173A - Process for cleaning of oil-laden metal waste to recover the metal and to reclaim the oil

Info

Publication number: US3846173A
Application number: US00342014A
Authority: US
Inventors: J Ihrig
Original assignee: FMC Corp
Current assignee: FMC Corp
Priority date: 1973-03-16
Filing date: 1973-03-16
Publication date: 1974-11-05
Anticipated expiration: 1991-11-05

Abstract

(C) MIXING THE SLUG WITH THE WASHED METAL WASTE; AND (D) DRYING THE MIXTURE OF SLUG AND METAL WASTE.

1. A CONTINUOUS NON-BATCH PROCESS FOR CLEANING OILLADEN METAL WASTE TO RECOVER THE METAL AND TO RECLAIM THE OIL CARRIED BY THE METAL WASTE, COMPRISING THE STEPS OF: (A) WASHING THE METAL WASTE WITH DETERGENT, AND EFFECTING RELATIVE MOVEMENT BETWEEN THE WASTE AND THE DETERGENT TO CREATE A COUNTER-CURRENT THEREBETWEEN; (B) SEPARATING OIL AND DETERGENT FROM THE WASH RESIDUE TO LEAVE A SLUDGE CONTAINING MOISTURE AND DIRT PARTICLES;

Description

IHRIG PROCESS FOR CLEANING OF OIL -LADEN METAL WASTE TO Nov. 5, 1974 RECOVER THE METAL AND'TO RECLAIM THE OIL 3 Sheets-$heet 1 Filed March 16, 1973 Nov. 5, 1974 .1. K. IHRIG 3,846,173

PROCESS FOR CLEANING OF OIL-LADEN METAL WASTE TO RECOVER THE METAL AND TO RECLAIM THE OIL Filed March 16, 1975 3 Sheets-Sheet 2 B6 n W I G a as 52 4o i: ll l 48 Nov. 5, 1974 J, |HR|G 3,845,173

PROCESS FOR CLEANING OF OIL-LADEN METAL WASTE T0 RECOVER THE METAL AND TO RECLAIM THE OIL Filed March 16, 1973 3 Sheets-Sheet 3 United States Patent O 3,846,173 PROCESS FOR CLEANING F OIL-LADEN METAL WASTE TO RECOVER THE METAL AND TO RE- CLAIM THE OIL John Kenneth Ihrig, Glenwood, 111., assignor to FMC Corporation, San Jose, Calif. Filed Mar. 16, 1973, Ser. No. 342,014

Int. Cl. B08b 3/08, 3/10; C23g 1/36 U.S. Cl. 134-10 22 Claims ABSTRACT OF THE DISCLOSURE A continuous process for cleaning metal waste, such as turnings, borings and chips. A detergent is contacted with the metal waste in a counter-current flow to remove 011 and other impurities and the wet sludge, removed during the clarification of the detergent solution in a rehabilitation circuit, is mixed with the cleaned metal waste and both are simultaneously dried. Makeup water is added to the cleaned metal waste ahead of the dryer to further rinse a substantial portion of any remaining detergent solution from the metal waste and this rinse liquid with the recovered detergent solution is returned to the rehabilitation circuit to reduce the amount of concentrated makeup detergent solution required.

BACKGROUND OF THE INVENTION Field of the Invention Large quantities of metal waste such as metal chips, turnings, borings, etc., are produced daily by manufacturing industries. The recovery of the metallic component and the reclaiming of the lubricating and/or cutting oils coating these metal particles are of commercial importance. To accomplish these ends it is necessary to remove impurities such as dirt from the mixture and to have a high percentage of oil and moisture removed from the metal component, usually to a level of less than 2 percent by weight on the recovered metal product, so the metal product is suitable for briquetting or for feeding directly to a melting furnace.

This invention relates to the art of cleaning metal waste, such as metal chips, turnings, borings, and the like, and reclaiming oil from such waste.

'Description of the Prior Art In the previously granted patents, U.S. 3,544,369 and U.S. 3,639,172 to James R. Keogh, In, and assigned to the same assignee as the present application, there are contained specific process steps for the cleaning of metal waste by washing in a detergent solution and the rehabilitation of the dirty washing solution so it can be recycled. In the rehabilitation of the detergent solution, wet sludge is removed from the detergent solution, but no means is disclosed for the continuous disposal of this separated sludge.

'In S. A. Goodstein, U.S. Pat. 3,163,929, dirty chips are washed in a detergent solution in a rotary drum and then further sprayed with detergent laden steam to dry the chips without any rehabilitation of the dirty detergent solution. In G. T. Hittel et al., U.S. Pat. 3,454,428, and in T. J. Kearney, U.S. Pat. 3,610,260, a chlorinated type of solvent is used to remove the oil. In G. T. Hittel et al. the solvent is further removed from the chips and recovered by use of centrifugal force. A more general type of process of cleaning oily chips by the extraction of the oil by centrifugal force is exempli fied by the following patents: U.S. 2,906,466 to A. O. Hoper; U.S. 3,656,620 to C. R. Larson et al. and U.S. 3,679,051 also to C. R. Larson et a1. Another general type of process of cleaning metal chips includes the burnice ing off of the oil and the evaporation of the moisture. This process is exemplified by the following patents: U.S. 2,852,418 and U.S. 2,925,821 both to W. D. MacDonald; U.S. 3,544,367 to F. Ehrlich et al.; U.S. 3,598,649 to A. M. Juhasz; U.S. 3,601,900 to M. J. Erisrnan et al.; U.S. 3,619,908 to W. C. Kallas and U.S. 3,656,735 to S. A. Eliot. A. H. Brisse, U.S. Pat. 2,529,762, discloses means for cleaning continuous metal strip in a cleaning solution and then drying the strip with the use of steam.

SUMMARY OF THE INVENTION In one step of the present invention, sludge removed from the metal during cleaning is mixed with the washed metal for drying. In another step of the method of the present invention, makeup water is added to the clean metal waste to rinse detergent remaining thereon into a settling tank for reuse.

In the preferred form of the invention, the process utilizes a heated detergent solution in a wash bath in which the metal waste is agitated to thoroughly expose all of the surfaces of the metal waste to the cleaning action of the detergent solution as it passes through the bath. The discharged clean metal is then further dried to reduce its moisture content. The dirty oil laden detergent solution is removed and passed through a rehabilitation circuit to clarify it by removing the oil and sludge contained thereon. Upon adding of makeup detergent and reheating of the restored solution, the added and restored solution is recirculated to the wash bath.

'In the clarification of the detergent solution, wet, sticky sludge (consisting of, for example, 35% moisture and fine particles, primarily dirt) is removed which is difficult to handle. Since a 20 ton per hour feed rate of metal waste on a continuous cleaning system might produce as much as 5 tons of sludge in 8 hours of operation, the problem of handling this sludge is of distinct importance. In the present invention, after the oil has been removed therefrom, this sludge is continually mixed with the feed of the cleaned metal waste going to the dryer. The wet sludge is then dried with the metal waste, and the fine light impurities pass out into the dust collector with the heated air. The heavier solids, usually metal, are discharged from the dryer with the dried metal waste.

In addition, in the preferred form of the invention further detergent solution can be recovered for recycling by adding the makeup water to the cleaned metal waste as it is conveyed to the dryer, thus rinsing this metal Waste of a substantial portion of any detergent solution remaining on the metal waste after it leaves the wash bath. This rinse water is then conducted to the settling basin in the rehabilitation circuit where it is added to the restored detergent solution, thus reducing the amount of required makeup detergent solution. Since it is estimated that makeup detergent is nearly 50 percent of the total hourly operating cost, the recovery and reuse of this detergent solution from the new rinsing operation will substantially reduce the hourly operating cost of the system.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of the apparatus used in the metal waste cleaning process of the present invention.

FIG. 2 is an elevational view of the apparatus used in the metal waste cleaning process of the present invention.

FIG. 3 is a cross-sectional view taken along lines 33 of FIG. 1.

FIG. 4 is a cross-sectional view taken along lines 4-4 of FIG. 1.

FIG. 5 is a diagrammatic view with certain components in section, showing the overall interrelationship between components of a metal waste cleaning system in accordance with this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present process of cleaning oil-laden metal waste provides improvements over the aforementioned U.S. Pats. 3,554,369 and 3,639,172, but utilizes the same types of detergent solutions described therein. One such solution employing Oakite No. 24, as made by Oakite Products, Inc., New York, N.Y., U.S.A., is an alkaline detergent containing soap, silicates and caustic. When used at a concentration of approximately this detergent has been found to provide desirable results with some metals, particularly cast iron and steel. Oakite cryscote No. 187, also made by Oakite Products, Inc., New York, N.Y., U.S.A., is an acidic detergent containing phosphates, activating agents and solvents, and, when used at a concentration of approximately 3%, has been found to provide desirable results with other metals, particularly brass. Although the type of detergent employed may vary depending on the types of metal and oil encountered, solutions ranging between 2% and by weight are effective in removing a substantial quantity of oil from the metal. In addition, detergent solutions of such strength allow the oil to separate from the detergent solution upon standing in a settling tank or upon the application of centrifugal force to such solution such as that encountered in a centrifuge. The retention time for the metal waste within the wash bath may vary depending upon the type of detergent employed and its concentration. Preferable results have been obtained using the Oakite No. 24 at 180 F. at approximately 5% strength with a retention time of two minutes while feeding metal waste to the washer at a rate of approximately 1750 pounds per hour and while recirculating approximately 8100 pounds per hour of detergent solution. The retention time, however, may vary within the range of one to six minutes.

In order to maintain the detergent solution at the desired strength and in proper condition for removing a substantial quantity of oil from the metal waste, it is necessary to remove or separate the sludge and oil and to add makeup detergent. It is also particularly desirable to heat the detergent solution to obtain maximum etficiency in removing the oil from the metal waste.

The apparatus used to carry out the present process is shown in FIGS. 1-4. FIG. 5 is a schematic flow diagram of the present process using the apparatus shown in FIGS. 1-4 and for which the same part numbers are shown for corresponding apparatus items; A washer, generally shown as 10, is fed with ground metal waste from a feed hopper 12 by a conveyor 14. The washer 10, has a tank 16 with an inclined bottom 17 forming a lower end 18 with an overflow weir 19 and an upper end 20 with a discharge chute 21. A power driven screw 22 is disposed within the tank 16 parallel to the inclined bottom 17. As illustrated in FIGS. 1 and 2, the washer 10 may contain two like units in series to provide longer retention time of the metal waste in the washer. Heated detergent solution is fed into the upper end of each washer from spray pipes 24. The detergent solution forms a wash bath 25 in the lower end 18 of each section of the washer. As indicated by arrow 26 (FIG. 5) the detergent solution flows down toward the lower end 18 while the screw 22 conveys the metal waste, submerged in the wash bath in the direction of arrow 28 upwardly toward the upper end 20 to obtain counterflow of metal waste and detergent solution. With the two units in series, as shown, the wash bath level in the second unit is maintained so that the detergent overflows into the first unit and when the wash bath level in the first, or lower unit, reaches the level of the overflow weir 19, the dirty detergent solution is discharged from .the washer through conduit 30. The inclined section of the upper end of the tank and the screw extends beyond the level of the wash bath towa d the discharge end to provide a drainage section for removing much of the moisture on the cleaned waste before the waste is discharged to chute 21.

The cleaned metal waste is transferred from chute 21 by a conveyor 32 to a drying system generally shown as 35. The dryer system 35 includes a rotary cylindrical dryer unit 36 with a drive 37 and a discharge hood 38, an air heater furnace 40, a dust collector 42 and an exhaust fan 44. The cleaned metal waste is fed into the dryer unit 36 through a feed inlet chute 46 and proceeds longitudinally through the dryer 36 to the discharge hood 38. Dryer unit 36 may be of the convention single shell type which is then positioned to rotate about an axis inclined downwardly toward the discharge and is driven by drive unit 37. The wet feed material is then lifted and tumbled, as the shell is rotated, through a hot air stream provided by the air heater furnace and caused to flow counterfiow to the metal waste by the exhaust fan 44 located beyond the dust collector 42. Dust collector 42, which may be of a conventional cyclone type, provides means for the dust and other fine impurities carried by the air stream to settle out of the air stream to a lower collection hopper 43 in the bottom of the dust collector. The dried metal waste is discharged from the dryer 36 into the discharge hood 38. Typical means of handling the dryer discharge, as shown in FIG. 4, may include a conventional power driven screw feeder 48, feeding the clean dried metal waste into a conventional power driven bucket elevator 50 which elevates this material to a convenient height where a second conventional power driven screw feeder 52 may feed this material to its point of ultimate use, such as a briquetting machine.

The dirty oil-laden detergent solution, after passing overflow weir 19, flows through conduit 30 to a detergent solution rehabilitation circuit generally indicated as 55 for removal of the sludge and oil picked up by the detergent solution in the washer 10. In the rehabilitation circuit, which follows the process disclosed in the aforementioned US. Pat. 3,639,172, the detergent solution is restored and is then recirculated through a conduit 56 to the spray pipes 24 on the washer 10.

In the rehabilitation circuit 55 (FIG. 5) the dirty detergent solution from the overflow weir 19 of the washer normally passes through conduit 30 and open valve 31 to a centrifuge 58 to remove any solids and the sludge present in the dirty detergent solution. The cleaned detergent solution is then passed through conduit 60 and pump 62, if required, to a settling basin 64. This settling basin is provided with a high level overflow weir to permit any excess solution to be accumulated in a storage vessel 66.

Storage vessel 66 also provides means for maintaining the continuous flow of dirty detergent solution from the washer while the sludge removal centrifuge 58 is intermittently shut down for cleaning and/or repairs so the metal Waste washing may proceed continuously. When the flow of dirty detergent solution to the sludge removal centrifuge 58 is thus interrupted, valves 31 and 33 (FIG. 5) are closed and valve 34 is opened. The solution is then diverted by passing through conduits 63a and 63b into storage vessel 66 until such time as the centrifuge 58 can accept more dirty detergent solution. At this

time valves

31 and 33 are opened and valve 34 is closed. The fiow will then pass from storage vessel 66 through line 63C and open valve 33 to the main conduit 30 feeding the centrifuge 58. With the reopening of valve 31 the fiow from the washer can flow to the centrifuge 58 simultaneously with the flow from storage vessel 66.

As a further alternate when the dirty detergent solution is diverted into storage vessel 66, the solution may be first passed through conduit 63d and over a screen 68 by clos- 'ing valve 34 and opening valve 67. Screen 68 will remove any relatively large size solids present in the dirty detergent solution before this solution is accumulated in storage vessel 66 and then released to the sludge removal centrifuge, thus relieving the centrifuge of the task of removing large size solids.

The sludge removed from the dirty detergent solution is discharged from the rehabilitation circuit 55 through a conveyor 70.

in the settling basin 64 the detergent solution, with the sludge removed, is permitted to settle forming an o l-r ch upper layer of the lighter oil. A portion of this oll-TlC h upper layer of detergent solution in the settling basin s continuously withdrawn through a conduit 72 to an oil separator 74, where the oil is separated from the detergent solution and collected in an oil tank 75. The oil-f-ree detergent solution is then returned to the settling tank through a pump 76, if required, and a conduit 77. Concentrated detergent solution makeup is added to the settling basin through a conduit 78 to restore the desired concentration of the detergent. The restored detergent solution in the settling basin 64 is heated, as by a hot water or steam coil 80 submerged in the detergent solution. The heated and restored detergent solution is then withdrawn from the settling basin 64, through an outlet 82 generally located well below the expected depth of the upper oil-rich layer, so as to avoid recirculating any oil in the detergent solution. This heated restored detergent is then passed by a pump 84, if required, through conduit 56 out of the rehabilitation circuit to the spray pipes 24 on the washer 10.

As the sludge is removed from the dirty detergent solution by the centrifuge 58 in the rehabilitation circuit, itis transferred by conveyor 70 to the end of conveyor 32 ad acent the feed end of dryer 36. At this point the sludge is then mixed with the cleaned metal waste and jointly fed into the feed chute 46 at the inlet of the dryer. As the sludge and metal waste is tumbled in the hot air stream of rotary dryer 36, the moisture is removed and the light fine particles are carried by the air stream as dust to the dust collector 42 where they are separated from the air stream and drop to the dust collection hopper 43 from which the dust particles may easily be disposed of in their dried form. The heavier solids, which from tests have greatly simplifies the disposal problem of the sludge. Due to the loss of water and detergent solution on the cleaned metal waste as discharged from the washer, and from the rehabilitation circuit in the form of the wet sludge removed from the dirty detergent solution, the restored detergent solution in the settling basin must be replenished and its concentration brought up to its desired strength before recirculating this restored detergent solution to the spray pipes 24 on washer 10. In this improved step, the makeup water is added from a fresh water supply conduit 86 through spray pipes 87 at the upper end of the conveyor 32, which carries the cleaned metal waste to the drying system 35, but just below the point at which conveyor 70 feeds the wet sludge into conveyor 32, so as to not dilute the sludge and possibly create a counterfiow with -the makeup water of some of the fines in the sludge back into the rehabilitation circuit. The makeup water rinses the cleaned metal waste of a substantial portion of any remaining detergent solution as the waste is being conveyed, usually on an incline so as to be elevated sufliciently to fiow by gravity into the dryer feed inlet chute 46. This rinse water with the recovered detergent solution then overflows an outlet weir 88 at the lower end of conveyor 32 and passes in conduit 90 to the setling basin 64 where it helps to replenish the detergent in the restored detergent solution. When the concentration of the detergent in the settling basin 64 is still not up to the desired strength, the balance of the required makeup is controllably added as concentrated detergent solution through the concentrated detergent makeup conduit 78 and valve 79 into the settling basin 64 where the various solutions from

conduits

60, 77, 78 and 90 have a chance to mix before recirculated through conduit 56 to the spray pipes 24 and washer 10. Thus, this further step of rinsing the cleaned metal waste with the makeup water provides a significant recovery in the amount of the relatively expensive detergent solution which can then be recirculated.

Although the best mode contemplated for carrying out the present invention has been 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 as defined by the attached claims.

What is claimed is:

1. A continuous non-batch process for cleaning oilladen metal waste to recover the metal and to reclaim the oil carried by the metal waste, comprising the steps of:

(a) washing the metal waste with detergent, and efi'ecting relative movement between the waste and the detergent to create a counter-current therebetween;

(b) separating oil and detergent from the wash residue to leave a sludge containing moisure and dirt particles;

(c) mixing the sludge with the washed metal waste;

and

(d) drying the mixture of sludge and metal waste.

2. The process of claim 1 including the step of blowing from the metal the dirt remaining after the moisture has been removed from the sludge in the drying process.

3. A continuous non-batch process for cleaning oilladen metal waste to recover the metal and to reclaim the oil carried by the metal waste, comprising the steps of:

(a) washing the metal waste with detergent solution, the metal waste moving in a direction opposite to the detergent solution and being agitated to give maximum exposure of the surfaces of the metal waste particles to washing by the detergent solution;

(b) reclaiming the detergent solution from the wash residue;

(c) rinsing the washed metal with water to remove any remaining detergent solution therefrom;

(d) adding the rinse water to the reclaimed detergent solution for reuse;

(e) removing a sludge containing moisture and dirt particles from the wash residue; and

(f) combining the sludge with the washed metal after the rinsing step.

4. The process of claim 3 including the step of adding detergent to the reclaimed detergent solution to achieve the desired concentration.

5. The process of claim 4 including the step of heating the reclaimed detergent solution with the added detergent.

6. The process of claim 5 including the step of recirculating the heated reclaimed detergent solution with the added detergent to the washing step.

7. A continuous non-bath process for cleaning oil-laden metal waste to recover the metal and to reclaim the oil carried by the metal waste, comprising the steps of:

(a) washing the metal waste in a wash bath with a heated detergent solution, the metal waste moving in a direction opposite to the detergent solution and being agitated to give maximum exposure of the surfaces of the metal waste particles to washing by the heated detergent solution;

(b) passing the dirty detergent solution removed from the wash bath through a rehabilitation circuit to separate a sludge containing moisture, fine dirt particles and fine metal particles and to remove oil from the dirty detergent solution;

(c) mixing the sludge with the washed metal waste;

(d) passing heated air through the mixed metal waste and sludge in a direction opposite to the flow of the metal waste and sludge to remove moisture therefrom; and

(e) recirculating the rehabilitated detergent solution to wash bath after adding concentrated makeup detergent solution and after reheating the combined solu tions.

8. The process of claim 7 including the steps of removing in the heated air passing through the mixed sludge and washed metal waste the fine dirt particles from the sludge and separating the fine dirt particles from the heated air in a dust collector.

9. A continuous non-batch process for cleaning oil-laden metal waste to recover the metal and to reclaim the oil carried by the metal waste, comprising the steps of:

(b) passing the dirty detergent solution removed from the wash bath through a rehabilitation circuit to separate a sludge containing moisture, fine dirt particles and fine metal particles and to remove the oil from the dirty detergent solution;

() adding makeup water to the washed metal waste removed from the wash bath and rinsing the washed metal waste to remove any remaining detergent solution therefrom;

(d) returning the rinse water with the detergent solution to the rehabilitation circuit for recovery of the detergent solution and reuse in the wash bath; and

(e) mixing the sludge with the washed metal after the rinsing step.

10. The process of claim 9 including the steps of adding concentrated detergent solution to the combined rehabilitated detergent solution and the returned rinse water to bring the concentration of detergent in the combined rehabilitated detergent solution and returned rinse water to the desired strength for washing oil-laden metal waste, reheating the combined detergent solution and rinse water and recirculating the heated combined detergent solution and rinse water of desired detergent concentration strength to the wash bath.

11. A continuous non-batch type process for cleaning oil-laden metal waste to recover the metal and to reclaim the oil carried by the metal waste, comprising the steps of:

(a) agitating and moving the metal waste through a flow of heated detergent solution forming a wash bath, the movement of the metal waste being in a direction opposite to the flow of the detergent solution and the agitation of the metal waste giving maximum exposure of the surfaces of the metal waste particles to cleaning by the detergent solution;

(b) removing the dirty detergent solution from the wash bath after its exposure to the metal waste and passing the dirty detergent solution through. a rehabilitation circuit, removing sludge and oil therefrom, to restore the detergent solutions cleaning capability,

(c) removing the cleaned metal waste from the wash bath and adding the sludge, removed from the dirty detergent solution in the rehabilitation circuit, to the cleaned metal waste;

((1) removing a substantial quantity of the remaining moisure from the cleaned metal waste with the added sludge; and

(e) recirculating the restored detergent solution to the wash bath after concentrated makeup detergent solution was added and the combined concentrated makeup and restored detergent solution were heated in the rehabilitation circuit.

12. A continuous non-batch type process for cleaning oil-laden metal waste to recover the metal and to reclaim the oil carried by the metal waste, comprising the steps of:

(b) removing the dirty detergent solution from the wash bath after its exposure to the metal waste and passing the dirty detergent solution through a rehabilitation circuit, removing sludge and oil therefrom, to restore the detergent solutions cleaning capability;

(c) conveying the cleaned metal waste from said wash bath and adding makeup water to the cleaned metal waste, said makeup water passing counterflow to said metal waste and rinsing a substantial portion of any remaining detergent solution from said metal waste;

(d) returning said makeup water with the additional rinsed-off detergent solution to the restored detergent solution in the rehabilitation circuit to thereby recover additional detergent solution and to reduce the amount of concentrated makeup detergent solution required;

(e) removing a substantial quantity of the remaining moisture from the cleaned metal waste; and

(f) recirculating the restored detergent solution to the wash bath after concentrated makeup detergent solution was added and the combined concentrated makeup detergent solution, the makeup rinse water, and the restored detergent solution were heated in the rehabilitation circuit.

13. A continuous non-batch type process for cleaning oil-laden metal waste to recover the metal and reclaim the oil carried by said metal waste, comprising the steps of:

(a) providing a flow of detergent solution in a first direction to form a wash bath for cleaning the metal waste by submersion in said detergent solution and for removing the oil carried by said metal waste;

(b) propelling the metal waste through the flow of detergent solution in a direction generally opposite to the direction of how of said detergent solution to provide counterfiow of metal waste and detergent solution, the propelling of the metal waste through the bath serving to agitate said metal waste and thereby to give maximum exposure of the surfaces of the metal waste particles to cleaning by said detergent solution;

(0) removing the cleaned metal waste from the wash bath;

(d) removing the detergent solution from the bath after its exposure to the metal waste and passing the detergent solution, carrying sludge and oil therewith, through a rehabilitation circuit to restore the detergent solutions cleaning capability;

(e) subjecting all of said detergent solution in said rehabilitation circuit to centrifugal force to separate sludge, acquired by said detergent solution in cleaning said metal waste, and containing moisture and lightweight dirt particles from the detergent solution and oil;

(f) conveying and mixing said separated sludge with the cleaned metal waste removed from the wash bath;

(g) removing a substantial quantity of the remaining moisture from said mixed metal waste and sludge;

(h) accumulating the separated detergent solution and oil in a settling basin in the rehabilitation circuit after the separation of the sludge;

(i) withdrawing a portion of the accumulated oil-rich liquid from adjacent the top of the settling basin, subjecting the withdrawn portion to centrifugal force to sepaarte the oil from the detergent solution to restore the detergent solution and returning the remainder of said withdrawn portion, from which the oil has been sepaarted, to the settling basin;

(j) adding concentrated makeup detergent solution to the restored detergent solution in the rehabilitation circuit;

(k) heating said makeup and restored detergent solution in said rehabilitation circuit; and

(l) recirculating the heated makeup and restored detergent solution from the rehabilitation circuit to the wash bath.

14. The process of claim 13 wherein the substantial quantity of remaining moisture is removed from the mixed sludge and metal waste by passing a stream of heated air through the mixed sludge and metal waste while moving through a rotary dryer.

15. The process of claim 14 wherein the sludge is added to and mixed with the cleaned metal waste as the waste is being conveyed from the wash bath to the dryer.

16. The process of claim 15 further including the steps of entrapping in the heated air stream the lightweight dirt particles remaining after the moisture has been removed from the sludge and separating the dirt particles from the n heated air stream in a dust collector.

17. A continuous non-batch type process for cleaning oil-laden metal waste to recover the metal and reclaim the oil carried by said metal waste, comprising the steps of:

(b) propelling the metal waste through the flow of detergent solution in a direction generally opposite to the direction of flow of said detergent solution to provide counterflow of metal waste and detergent solution, the propelling of the metal waste through the bath serving to agitate said metal waste and thereby to give maximum exposure of the surfaces of the metal waste to cleaning by said detergent solution;

() removing the detergent solution from the bath after its exposure to the metal waste and passing the detergent solution, carrying sludge acquired by the detergent solution in cleaning said metal waste and oil therewith, through a rehabilitation circuit to restore the detergent solutions cleaning capability;

(d) subjecting all of said detergent solution in said rehabilitation circuit to centrifugal force to separate Sludge from the detergent solution and oil;

(e) accumulating the separated detergent solution and oil in a settling basin;

(f) withdrawing a portion of the oil-rich liquid from adjacent the top of the settling basin and subjecting the withdrawn portion to centrifugal force to sep arate the oil from the detergent solution to restore the solution, the remainder of said withdrawn portion, from which the oil has been separated, being returned to the settling basin;

(g) removing and conveying the cleaned metal waste from said wash bath;

(h) adding makeup water to the cleaned metal waste being conveyed from said wash bath, said makeup water passing counterflow to said metal waste and rinsing a substantial portion of any remaining detergent solution from said metal waste;

(i) passing said makeup water with the additional rinsed-01f detergent solution to the settling basin in said rehabilitation circuit to thereby recover additional detergent solution;

(j) separating a substantial quantity of the remaining moisture from said cleaned and rinsed metal waste;

(k) adding concentrated makeup detergent solution to the restored solution in the rehabilitation circuit;

(1) heating said makeup and restored detergent solution in said rehabilitation circuit; and

(m) recirculating the heated makeup and restored detergent solution from said rehabilitation circuit to said wash bath.

18. The process of claim 17 further including the step of adding and mixing the sludge, separated from the detergent solution in the rehabilitation circuit, with the cleaned metal waste being conveyed to the means for separating a substantial quantity of the remaining moisture in the metal waste.

19. The process of claim 18 wherein said sludge is added to the cleaned metal waste as it is being conveyed but after the point at which the makeup water is added to the metal waste to avoid rinsing and further dilution of said sludge as it is being mixed and conveyed with the metal waste to the means for separating the remaining moisture.

20. The process of claim 17 further including the step of accumulating the detergent solution, with the sludge and oil therein as removed from the wash bath, in a storage vessel prior to subjecting the detergent solution to centrifugal force to separate the sludge, to enable continuous operation of the wash bath while the means for separating the sludge by centrifugal force is intermittently shut down for cleaning.

21. The process of claim 20 including the further steps of providing for the overflow of any excess liquid in the settling basin and passing this overflow of excess liquid to the storage vessel.

22. The process of claim 20 including the further steps of screening the detergent solution, with the sludge and oil therein as removed from the wash bath, to remove any larger size solids from the solution and passing the undersize material from the screening step to and accumulating this undersize material in the storage vessel.

References Cited UNITED STATES PATENTS 3,639,172 2/1972 Keogh l3425 R 3,544,369 12/1970 Keogh 13425 R 3,610,260 10/1971 Kearney 134-19 X 2,852,418 9/1958 MacDonald 1'34-2 2,925,821 2/1960 MacDonald 13410 X 1,580,723 4/1926 Hapgood 13410 3,734,776 5/1973 Keogh 134-25 R 3,598,649 8/1971 Juhasz 134--25 R X 3,454,428 7/1969 Hittel et al 13425 R 3,163,929 1/1965 Goodstein 134-25 R 3,767,179 10/1973 Larson 1342 X S. LEON BASHORE, Primary Examiner R. H. TUSHIN, Assistant Examiner US. Cl. X.R.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENTNO.: 3,846,173

DATED November 5, 1974 |NVENTOR(5) 1 JOHN KENNETH II-IRIG It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

line 70, change "Hoper" to --Hopper.

Column 1,

Column 3, line 5, change "3,554,369" to 3,544,369-. Column 4, line 59, change "63C" to --63c--.- Column 6, line 1, insert being-- before "recirculated".

Column 8, line 72, change "sepaarte" to separate; line 75, change "sepaarte" to -separate.

Signed and Sealed this sixteenth D ay Of December 19 75 [SEAL] AIICSI.

RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner nj'Parenrs and Trademarks

Claims

1. A CONTINUOUS NON-BATCH PROCESS FOR CLEANING OILLADEN METAL WASTE TO RECOVER THE METAL AND TO RECLAIM THE OIL CARRIED BY THE METAL WASTE, COMPRISING THE STEPS OF: (A) WASHING THE METAL WASTE WITH DETERGENT, AND EFFECTING RELATIVE MOVEMENT BETWEEN THE WASTE AND THE DETERGENT TO CREATE A COUNTER-CURRENT THEREBETWEEN; (B) SEPARATING OIL AND DETERGENT FROM THE WASH RESIDUE TO LEAVE A SLUDGE CONTAINING MOISTURE AND DIRT PARTICLES;