US2150899A

US2150899A - Method of and apparatus for isolating minerals

Info

Publication number: US2150899A
Application number: US98819A
Authority: US
Inventors: Henry L Alexander; Pont Hubert I Du; Willing B Foulke
Original assignee: EI Du Pont de Nemours and Co
Current assignee: EIDP Inc
Priority date: 1936-08-31
Filing date: 1936-08-31
Publication date: 1939-03-21
Anticipated expiration: 1956-03-21
Also published as: FR830757A; US2277053A; US2278906A; GB501655A; US2266840A; GB501656A

Description

11 Sheets-Sheet l Filed Aug. 5].

H. L. ALEXANDER ET AL METHOD OF AND APPARATUS FOR ISOLATING MINERALS March 21 1939.

INVENTO R5 0 6176i. dwPom f s Mwch 2 11, 1%39.

H. L ALEXANDER ET AL 2,159,899

METHOD OF AND APPARATUS FOR ISOLATINC; MINERALS 11 Sheets-Sheet 2 Filed Aug. 31, 1936 INVENTORS flamy Lflemmdez: Hubert l. dwPont an BY ILLZIZG,

922 gm Wm ATTORNEY METHOD OF AND APPARATUS FOR ISOLATING MINERALS Filed Aug. 31, 1936 ll Sheets-Sheet 3 JSKBU! 556 f 35 i am 359 514 m I Z0 I 513 334 .514 321 $24 if I INVENTO RS g yLflis/r amiei; 19 Z ZLZZU 1i Sheets-Sheet 4 Filed Aug. 51, 1956 H L ALEXANDER ET AL METHOD OF AND APPARATUS FOR ISOLATING MINERALS v Hen 7 Marrdn 21, 1939.

March 1939- H. L. ALEXANDER El AL 2,150,399

METHOD OF AND APPARATUS FOR ISOLATING MINERALS Filed Aug. 51, 1936 ll Sheets-Sheet 5 500006600000. oooooo aececono be ua0ncooe O n o 0 I: a o 0 G 0 Q a mmw. H

March 21, 1939. H. ALEXANDER El AL 2,150,899

METHOD OF AND APPARATUS FOR ISOLATING MINERALS Filed Aug. 31, 1956 ll Sheets-Sheet 6 Hera Hub ATTORNE March 21, 1939- H. 1. ALEXANDER ET AL METHOD OF AND APPARATUS FOR '[SOLATING MINERALS Filed Aug. 51, '1936 11 Sheets-Sheet '7 w. V T v .M \NQ Henry Hub .FouUfe,

ww kNN March 21, 1939- H L. ALEXANDER ET AL 2,150,899

METHOD OF AND APPARATUS FOR ISOLATING MINERALS Filed Aug. 51, 1936 11 Sheets-SheetB 4 430 44? n j :Eh Di D kw INVENTORS Hell 1 Lflleramiez:

Hubert J. duPo; (i a BY 1"). I M166,

ATTORNEY March 21, 1939. H. L. ALEXANDER ET AL METHOD OF AND APPARATUS FOR I SOLATING MINERALS Filed Aug. 31, 1936 ll Sheets-Sheet 9 INVENTO RS HemyLflZerande t fi g litl. dzbPont a ATTNEY March 21, 1939.

H. L. ALEXANDER ET AL METHOD OF AND APPARATUS FOR ISOLATING MINERALS Filed Aug. 31, 1956 ll Sheets-Sheet l0 6 W Q v z w m w 6 6 6 w .L

INVENTO RS flenryllfllexmzder, H ubertl dzbPonllw BY Milinyfi.]%ulle,

ATTORNEY arch 21, 1939.

H4 L. ALEXANDER ET AL METHOD OF AND APPARATUS FOR ISOLATING MINERALS Filed Aug. 31, 1936 ll Sheets-Sheet 11 INVENTORS HGJUyLMQ Zexandei; Hubgzf 1. dLLPO/Lk a wwwfi .Foullfie,

ATTORNEY Patented Mar. 21, 1939 NITED STATES PATENT OFFICE METEOD F AND APPARATUS FOR ISOLAT- HNG MINERALS ration oi Delaware Application [August 31., 1936, Serial No. 98,819

llii @iaiins.

This invention relates to the separation of minerals from gangue by the use of a liquid. of specific gravity between that of the mineral and the gangue. The invention will be described as it is applied to the separation of coal from its indigenous impurities, particularly slate, a separation in which the process and apparatus are of particularly great value, but it is to be understood that this description is illustrative, not linilll itative.

Coal appears to have been known, and to some small extent used by, the ancients. Its use in China at about the year 1200 is described by Marco Polo and about 1500 Agricola described it a process of freeing minerals from their gangue which is the direct progenitor of the jig process of coal cleaning, which has the widest use today. In the early days of coal mining in Europe and in the United States only the thick seams were as mined. Hand methods were largely in vogue and the need for anything except hand cleaning, or the most crude of mechanical methods was unnecessary. As the thick seams were used up, however, it became necessary to use thin seams '25 and seams containing veins of rock, which entailed the necessity of removing the rock before the coal could be sold. The method which came most prominently into use and which is today the standard of separating coal and slate deso pends upon the rates at which bodies of difierent densities sink through a liquid such as water. It is known that bodies sink through a. liquid at rates which are functions of their respective densities, the denser sink the more swiftly. The

35 standard jig washer of the industry takes ad.- vantage of this principle, but instead of permitting the solids to sink through the liquid, the liquid is forced through a screen on which the solids rest at a rate which lifts the layer of coal 4.9 or; the heavier slate, the coal being carried with the rush of liquid over a weir and the slate being discharged at a lower point from the screen. Jigs are highly developed and are of excellent capacity and performance. However, the compe- 45 tition of cit has driven coal producers to find means of cleaning coal which will be more accurate in separating useful from useless lumps and producers and inventors have turned their thoughts to those processes of separation which 50 depend upon the parting action of a liquid having specific gravity between that of coal and that of slate.

The use of a parting liquid is to be distinguished from froth flotation. Froth flotation a1- .55 ters the apparent specific gravity of a body by encasing it within a. bubble. Parting processes. however, depend upon the use of a parting liquid in which one ingredient of the mixture will sink down and another ingredient of the mixture will rise to and float on the top. Certain phases of 5 the parting liquid process are affected by the phenomenon of altered specific gravity but they are distinguished from froth flotation.

The suggestion was made toward the middle of the nineteenth century that ferric chlorideor l0 sulfuric acid could be used as a parting liquid for the separation of coal and slate and attempts were made in England to run the ferric chloride process in competition with the jigs, but the jigs were highly developed, the use of a part= l5 ing liquid was a bare suggestion and the attempt was a failure because of the undeveloped state of the new process, the highly developed state of jig separation, and the inability of experimenters to make the parting process a success in itself. The original attempt having been made, however, subsequent inventors worked with the suggested process and a host of patents have been issued, particularly in England and in the United States, dealing with processes of the parting liquid type. To the best of our knowledge and belief, however, the only such process that has been used successfully is one that depends upon the parting efiect of a suspension of solids such as sand or clay in water. The art with respect 3Q.

century, unable to compete. The parting liquids are worth more than the coal and the losses thereof are so great that they outweight the 5 theoretical advantages of more accurate separation. The processes themselves, being crude and undeveloped, are incapable of competing with the highly developed processes already in use in the industry. They are incomplete processes, lacking a number of elements essential to success.

t is an object of this invention to separate coal from slate, and other minerals from their gangues or from each other, by a process which depends upon the parting effect of a liquid of intermediate specific gravity. Another object of the invention is to present an apparatus so highly developed that it may compete successfully with the highly developed processes and apparatus of the prior art. Another object of the invention is to bring into the mineral separations art new methods and apparatus for separating minerals from their gangues.

The objects of the invention are accomplished, generally speaking, by immersing the mixed minerals and gangue, preferably under hermetical seal, in a parting liquid of specific gravity intermediate, the specific gravities of materials to be separated, withdrawing the separated constituents from the parting liquid, scrubbing them to remove adhering parting liquid, prei'erably under hermetical seal, and ejecting them, preterably through a hermetical seal, from the process, and recovering parting liquid from the scrubbing liquid in a semi-static settling system.

The objects of the invention are also accomplished in part by the association oi apparatus hereinafter more fully described. The ob- Jects oi the invention are in some degree accomplished by the details of the apparatus and. proceas which are more completely elsewhere herein described.

In order to make the drawings more easily comprehensible the first figure has been called Figure l, and is the key figure; the steps of the 'process have been numbered from 3 to 9 consecutively and the figures of the drawings have been numbered to correspond with the steps of the process to which they refer. For example, on the key figure (Figure l) the numeral 3 refers to the step of the process which involves the actual parting step. The sheets which relate to that step are numbered from Figure 3 to Figure 31. Figure 2 is a view of the pipe Joints which are used throughout the apparatus.

Figure 3 is an apparatus capable'of carrying out the parting step of the process; Figure 3 is a vertical section on the line A-A of the key figure; Figure 3a. is a cross section on the broken line 3a, 3a of Figure 3; Figure 3b is a detail, partly in section, of a preferred modification 01' wedge 336-33l; Figure 3c is a section on Figure 3!); Figure 3d is an elevational view partly in phantom and partly in section showing the parting apparatus; Figure Se is a section of line 3e, 3e of Figure 3d; Figure 3f is a section of line if. if of Figure 3d; Figure 3a is a section on line V 3g, 3g of Figure 3; Figure 3h is a section on line an, in of Figure 3; Figure 31' is a section on line 3i, 3: of Figure 3; Figure 37 shows means for operating the preferred embodiment of Figures 3b and 30; Figures 3k and 31 show a preferred method of operating the apparatus of Figm-es 3b and 3c.

Figure 4 is an elevational view partly broken away and in section showing the scrubbing apparatus; Figure 4a is a section on the line 4a, 4a of Figure 4; Figure 4b is an enlarged section on the

line

4b, 4b of Figure 4d, the left hand section Figure 4b taken on the line Z-Z of Figure 4d; the middle section of Figure 41) being taken on the line YY of Figure 4d; and the right hand section of Figure 4b being taken on the line XX of Figure 4d; Figure 4c is a section on the line 40, 4c oi. Figure 4; Figure 4d is an enlarged section of the sealing mechanism shown in Figure 40; Figure 4e is an enlarged section of a spray pipe with nozzles showing the overlap of the sprays.

Figure 5 discloses the apparatus for receiving material discharged from the scrubbing process, for sealing the scrubbing process, and for discharging the material.

Figures 6, Q, 6b, and 6c disclose the second, or main, settling tank, being the second step in the heavy liquid recovery system of which the first step is the settling tank, the apparatus which is found within the scrubbing section. Figure 6 is a plan view partly cut away and in section of the main settling tank; Figure 6a is a section on the line la, 8a; Figure 6b is a vertical section on the line 8b, 8b; Figure 6c is an enlarged section on the line 60, 6c of Figure 6.

Figures 7 to 7c refer to the third settling tank of the series, so-called the sludge trap, and to the still. Figure 7 is an elevation partly in section of the sludge trap and still as assembled; Figure 7a is a plan view of the sludge trap; Figure 7b is a cross-section of the sludge trap on line 1b, lb: Figure 7c is a plan view of the still on the line 10, 1c of Figure 7.

Figures 8 to 80 do not refer to section 8 of the apparatus, but to an apparatus by means of ,which the eficiency of separation can be expeditiously determined. Figure 8 is an elevation of a portion of the apparatus partly in section and Figure 8a is a cross-section on the line 8-2,

' 8--2 of Figure 8. Figure 8b is a drawing of a scoop; Figure 8c is an enlarged detail of the hinge connection.

Figure 9 and Figure 9a are views in plan and elevation, respectively, of the condensers.

In order to simplify the comprehension of the invention the path of the coal through the apparatus will be traced to completion before the treatment of used liquids is considered. The coal is dropped into chute 328 and is carried thereby into the separating chamber where the heavy material is separated from the light by a liquid medium of intermediate specific gravity. After the separation the coal is drained of entrained liquid and transferred to the apparatus and step 4 of the process which is, with respect to the coal, a scrubbing process which removes from the coal substantially all vestiges of parting liquid. In this scrubbing step the separated coal and slate are subjected to a vigorous scrubbing by water, under pressure, which comes from headers M2. The steps of the process are preferably carried out in a hermetically sealed system. The washed coal and slate are ejected through split boot 462 into the water-sealed conveyers 5 which serve to give the coal a last rinsing and to prevent the escape of vapors from the sealed

units

3 and 4. From the conveyors 5 the coal may be discharged to storage or to a railroad car for transportation to the place of use and the slate may be discarded.

When the coal passes through the scrubbing section 4, it is vigorously scrubbed with water from the headers 442. The coal passes on and the water passes through the screen which carried the coal and, together with sludge and heavy liquid, gathers in tank 406 which forms the lower part of this section of the apparatus. From that tank the sludge is removed through pipe 451 to be discharged into the sludge trap l, and the liquid containing fighter suspended matter is discharged into the main settling tank 6. Over the weir at the top of the main settling tank 6 flows comparatively clear liquid to be pumped through pipe M5 to headers 2 for reuse in the washing section. From the bottom of the tank 6 the sludge is drawn through pipe 620 and pumped to the sludge trap Z. From the sludge trap 1 on some occasions substantially the entire contents are dropped into the still 8 for steam distillation, but in normal and preferred operation the matter is allowed to settle into three layers, the bottom of which is largely solid, the middle of which is largely heavy liquid and the upper of which is substantially water. Through the pipe 1|! which leads .to a weir at the top of the tank and through valves H9 and pipe 'l2l the water is drawn oil and returned to the tank 6.

-closed tank; 3!

The heavy liquid is pumped through P19 123 to the used liquid storage tank. Finally, the remaining sludge is dropped into the still 8 for steam distillation. The water, together with vaporized heavy liquid, passes through pipe 88-39 to condenser 9 which is diagrammatically shown on this figure, and from condenser 9 to cooler 95 and water separator 96, wherein the heavy liquid is separated by a gravity separation from water. The separated heavy liquid is carried through pipes SH and 962 to the new liquid storage tank 963 or the used liquid storage tank 964, respectively. 965 is a vent pipe connecting the used liquid storage tank with the new liquid storage tank and 966 is a vent from the new liquid storage tank. The used liquid storage tank can be replenished from the new liquid storage tankthrough meter gauge 961, which gives a check on the amount of liquid used in the system. The level of heavy liquid in the parting section 3 is maintained by injecting liquid from the used storage tank 364 through pipe 359. Excess of heavy liquid escapes over a weir through pipe 358 and back to the used liquid storage tank. In the drawings a circle with the letter p indicates a pump and a circle with the letter 0: indicates a valve; pipes 358-359 are joined by a pipe in which is valve V-20.

In Figures 3 to 31 is illustrated the separating chamber. Referring to the numerals, 3 is an enare channel-shaped edges to openings in the top of the tank; 32 are covers for the said openings; 33 are flanges on the said covers of size to flt within the said channelshaped edges of the openings; 34 is a liquid which partially fills each said channel-shaped opening forming a hermetical seal; 35 is a vent pipe; 37 is a motor support mounted on the said tank; 36 is a motor of variable speed; 39 is a speed re-- ducing gear of customary construction comprising a chain of large and small driving and driven wheels; 300 is a shaft running crosswise of and projecting somewhat beyond the sides of the tank; 309 and 302 are sprocket wheels keyed to the shaft 300 at opposite ends thereof; 303-304 are chains on opposite sides of the tank driven from the said sprocket wheels respectively; 305- 306 are sprocket wheels mounted on the ends of shafts 301 and 306 respectively, said shafts passing through the wall of the said tank; 309-309 are stufhng boxes which can be filled with grease from the outside of the tank through the fittings 3E0; 3l2 are sprocket wheels keyed to the shaft 308; 313 are wheels mounted on shafts 3 which are journaled within the tank; 3E5 is a wedgeoperated take-up mechanism whereby one roller 3l3 can be moved longitudinally of the machine to take up the slack in the chain. One take-up means is placed at each end of the roller.. 3l6 is a screw for operating the wedge and moving the roller; 3 l 1-3 I! are conveyor chains; 3 l 8 is a flight of a conveyor which is mounted on the conveyor chains 31?; 3l9 are perforations in the flights of the conveyor; 320 is a conveyor panbent at the point 32! and having a discharge lip and chute 322; 323 is a wedge-wire screen forming the bottom of the upper portion of the conveyor pan; 324' is a section of the tank wall spaced considerably away from the said screen to permit liquid to make its way through the said screen and to be collected in the said portion of the tank; 325 is a channel leading from the portion 324 past the outside of the tank and connecting with the interior of the tank at 326; 321 are blow-out connections to permit the forcing of a stream of water or other liquid into the tank at that point; 323 is a chute projecting through the side of the tank; 329 are dividing walls in the chute; 330 is the back plate of a hopper; 33| are perforations in the back part of the hopper; 332 is a portion of the hopper back plate which is inclined diagonally forward and which contains the perforations 33l; 3320-3320 are perforated portions of the said back plate of the hopper which are continued beyond the side plates thereof; 333- 334 are side walls of the said hopper, both being inclined inwardly to the degree necessary to constrain any material entering through the chute 328 and passing to the bottom of the tank to fall within the conveyor pan; 335 is the front wall of the said chute which is constructed, in the form of the invention shown inFigure 3, as one piece of the front conveyor pan; 336 is a section of the said wall inclined diagonally toward the receiving end, and 331 is a portion of the said wall inclined toward the discharge end whereby to present the wedge face toward the charging end; 338 is a conveyor pan; 339 is a wedge-wire screen forming the bottom of the upper portion thereof; 340 is a discharge chute attached to or forming a part of the said conveyor pan; 34l-34l are sprocket wheels on the shaft 301 over which are trained the chains 342-342 of a flight conveyor 343; 344 is a bend in the said flight conveyor pan; 345 is a shaft carrying two sprocket wheels at the said bend; 346 is an extension of the conveyor pan beyond the sprocket wheels 345 and being continued downwardly to form the wedge; 34! are means for adjusting the position of the sprocket wheels 348 which are mounted on a trunnion to carry scraper flight conveyor 343; 349 is a pan extending from side to side of the machine to catch the drip which passes through the wedgewire screen 339 and return it to the liquid in the tank; 350 is a drain at the rear and lowest point of the tank, whose bott m is preferably inclined; 35l is a chamber beneath the said screen; 352 are a pipe and valve to permit the drawing off of the sludge which may collect and pass through the said screen, the said sludge being passed through the said pipe to the Settling tank to be hereinafter described, the continuation of the said pipe not being shown; 353 is a chamber attached to the wall of the tank; 354 is a screw operating in a nut 355 fastened to the tank; 356 is a stuffing box through which the said screw passes; 35? is a cylinder attached to the said screw; 358 is a pipe projecting within the box 353 and within the cylinder 351 having therewith a movable fit made liqulcf-tight by machining or by the use of a satisfactory sealing.material; 359 is a valved pipe leading to the box 353; 360 are openings .below the parting liquid level connecting tank 3 and weir box 353; 360i is an opening connecting weir box and tank above the water level; 36| ,is an enclosed weir. box on the side of the machine; 362 is a pipe weir within the box to control the water level. The pipe 362 is connected to the settling tank. 363 is a pipe leading at 364 and 365 into the tank; 366 is a hollow gauge within the pipe 363 and projecting thereabove. Shaft 366 of the said gauge is preferably calibrated on its outside and its hollowness is used for the insertion or withdrawal of shot or other heavy material to its interior so that it can be standardized against the specific gravity of the parting liquid in the apparatus to record correctly its level; 361-368 are oppositely placed hollow projections on the sides of the apparatus; 369- 310 are removable covers held on by bolts or other satisfactory means not shown to hennetically seal those of the said openings which are not in use; 31l-31l are flanges on the said projections designed to abut against and form a hermetical seal with similarly placed flanges or similarly pro- Jectlng members of that apparatus 4 which accomplishes the next step in the process; 3233 is a manifold forming a part of the chute connected vto a suction apparatus not shown and through openings 326i to the chute whereby any escaping gases may be caught; 312 indicates the framework which supports the tank; the line 313 indicates the upper level of the liquids in the tank; the line 314 indicates the interface of the separating liquid and the light liquid; 315 is a pipe opening into the tank whose purpose will be hereinafter described; 311-311 are angle bars supported either from the members 332 and 331 or from the sides of the tank by bars which cover the conveyor chains and prevent them from being damaged by the descending slate; 319 is a screen extending preferably the full depth of the liquid to prevent light materials from being washed back into the path of the outer conveyor. The screen stretches from wall to wall of the tank between the chute and the outer conveyor and from a point slightly above the level of the liquid to a point Just short of the lower conveyor.

This apparatus is operated to accomplish the above described step of the process as follows: The valve of pipe 359 is opened and heavy liquid is admitted to the tank through openings 36!] until the level 314 is indicated on the sight gauge 366. Water is then run into the tank through the orifices 315 until the level 313 is reached. A continuous flow of water may be maintained through the machine through the pipe 315 and the overflow 362, if it is desired, or water may be added intermittently and as needed. The height of the parting liquid in the tank is regulated by the overflow 351. As the liquid is admitted it rises in the tank and in the box 353 until it reaches the open top of the cylinder 351 at which point it flows downwardly through the said overflow and through the valve and pipe 358 to the used liquid tank. The valve in the said pipe 356 may be kept open and a continuous flow of liquid pass into the chamber through pipe 359 and out of it through pipe 358, or the operation may be made intermittent, control being kept by observation of the sight gauge.

The tank having been filled to the proper level withliquid, coal is dropped from the conveyor into the chute 326, passing in four streams down the divisions 329 by which it is distributed across the width of the tank. The chute 328 may be placed on either side of the machine as is indicated in Figure 3e, an opening on either side being provided, that not in use being closed by a plate 316. The apparatus is started; the motors drive the two conveyors either at the same or at diflerent speeds depending to some extent upon the quantity of material each has to handle. The coal, slate, and other admixed impurities drop into the water layer while still in the chute so that they are dispersed by the water before reaching the parting liquid; the splash made by their falling is dissipated and entrained gas is removed before they leave the chute. Passing through the water layer they enter the parting liquid, whose density has been selected to be between that of coal and that of slate. The coal floats on the surface of the parting liquid, the slate sinks down guided by the hopper 334 and,

entering the conveyor pan, is picked up by the scraper conveyor blades and carried toward the discharge. The coal floating at the interface of the liquids is picked up by the conveyor 343 and carried toward and onto the conveyor pan 346. The speciflc gravity of the liquid is preferably chosen to be only slightly lower than that of the middlings. The middlings are those portions of the mixture which contain in one lump both slate and coal. The middlings tend to sink only slowly in the liquid whereas the slate sinks instantly and the coal floats.

Each of the conveyors acts as a pump, the effect of which can be varied by the use of scraper blades of either solid or foraminous cross section, the number of openings in the said scraper blades being variable to secure pumping actions of different intensity. As the outer conveyor sweeps sunken material along its conveyor pan and up the incline toward the discharge, some of the entrained liquid tends to fall back through the orifices in the flights and that which remains is sucked out of the material as it is pushed over the wedge-wire screen 323. The slate is discharged through the hopper 322 into the trough 4| which forms a part of the apparatus 4 to be hereinafter described. The lower plate of the conveyor pan of the inner conveyor 338 is carried well beyond the pinion 345 and is then bent inwardly as indicated at 3466 so that the floated material will be swept on without jamming between the fiights and the pan. By carrying the conveyor pan beyond the sprocket wheels345 the chain is enabled to bend upwardly, and enough slack is provided therein so that when coal tends to jam the conveyor by taking up slack it may jump and release it without damage. The conveyor flights then sweep the coal up the inclined pan, over the wedge-wire draining screen 339, and eject it through the hopper 34!] onto the trough 42 which forms aportion of the apparatus 4 to be hereinafter described. The liquid which is driven by the outer conveyor passes through the wedge-wire screen 323 downward through the chamber 324, outside the main wall of the tank through the passage 325 and the opening 326 into the chamber which is formed in back of the partition 336-331. The liquid which is entrained by the inner conveyor is swept up the inclined conveyor pan, passes through the wedge-wire screen 333, flows down the drain board 349, and is carried back to the chamber behind the partition 336-331. Sides 333-334 of the trough, together with the sides of the tank, form tubes 386-38l through which liquid from channel 325 and the chamber beyond 336-331 may travel to the receiving end of the machine, entering again into the separating chamber through the orifices 33! of the plate 330. There is thus maintained a constant motion of separating fluid and its superimposed sealing liquid from the receiving toward the discharge end of the machine. The length of the separating chamber, namely the distance between the plate 330 and the wedge 336-331 is such that the pieces of coal will have risen to the top of the separating liquid and the pieces of slate will have dropped to the bottom before the wedge has been reached, but the middlings, due to the selection of a parting liquid of only slightly lighter specific gravity, will be held in suspension, slowly sinking. The middlings rich in coal sink at a slower rate than the middlings poor in coal, due to their difierent densities, and a classification of the middlings takes place before the wedge is reached. The wedge then directs the richer midarouses dlings upward into the coal and the coal-poor middlings downward into the slate.

In Figures 310 and 3c is shown a means of varying the proportion of middlings which is thrown a into the coal and a means which materially contributes to the production of coal with a standard ash content. In those figures 346 is the bottom of the conveyor pan; 383 isa plate; 382 is a hinge connecting the plate to the lip of the conveyor pan; 385 is a plate and 33B is a hinge connecting the plate 385 to plate 383; 381 are hook-shaped members which underlap the edges of the channel irons 3H for sliding movement. On the plate 383 at a point near the hinge 386 there is connected a lifting rod or cable 38'? which extends upwardly between the conveyors and the wall of the tank and through a water seal box 368 mounted in the side of the tank to a point on the outside from which it may be manipulated. 389 are rods. By pulling up on one said rod the plate 3% will be lifted, and the plate 385 will swing toward the receiving end of the machine, theedge 3% of the wedge will have been raised and a greater proportion of the middlings will have been directed into the slate, producing a coal of decreased ash content. If, on the other hand, a coal oi increased ash content is desired, a second rod attached at the lower end of plate 385 and projecting through the wall of the tank in the same manner may be manipulated to draw the plate 335 rearwardly and lower the angle 386. As shown in Figure 372 enough room exists between the edge of the conveyor flights and the wall of the tank to permit the passage of a rod, and by stationing and sealing tank 388 entirely outside of the wall 33 no interference between the conveyor and the rods will be experienced. The lower end of the rod may be attached to the wedge by a cable, as shown.

In Figures 37c and 31 is shown another means of adjusting the wedge. In those figures 3 refers to the tank; 39d39ll are elongated boxes on the outsides thereof (a corner of which is shown in dotted lines in Figure 3) 3% are slots connecting the interior of the tank with the said boxes; $92-$92 are links attached to the lower corners of the wedge; 393-393 are pins attached to the links, passing through the slots 3% and mounted in movable blocks 39 i; 39-39t3 are rods attached to the said blocks bored and screwthreaded; 3%396 are revclvable screws mounted in bearings attached to the sides of the boxes hearing at their heads pinions which mesh with pinions on shaft 398 which is mounted in the sides of the tank and projects through the wall of the box and a stuiflng box 33?; 393 is a hand wheel to turn the rod.

The operation of this apparatus is as follows: The hand wheel 399 is turned, rotating the inter meshed pinions and the rods 395 which extend or restrict the blocks 3% by reason of their screw fit with the interior of portions 395. As the blocks 3% are moved along the boxes, they push the link 392, which being attached to the corners of the wedge 3855 move the wedge as indicated in part by the dotted lines of Figure 37a.

A brief description of the apparatus is as follows: The material to be separated enters through the chute into the receiving .end of the apparatus and is collected by the hopper which encircles the section of the apparatus in which the actual parting of mineral and gangue takes place. The pumping action of the conveyors keeps the liquid in continuous circulation from the receiving end of the parting chamber to the discharge end thereof. The upper conveyor sweeps the floats onto the conveyor pan, and the looseness of the conveyor chains permits the conveyor .flights to jump and free themselves from any particles which tend to jam against the lip of the conveyor pan. The lower flight gathers the sinks and carries them out of the separating chamber. The middlings are carried by the current toward the wedge which forms the discharge end of the separating chamber and are divided according to the proportion of slate and coal they contain, those heavy because of large quantities of slate being thrown into the refuse, and those light because of usable quantities of coal being gathered in the floats. The separated materials are pushed by their respective conveyors over wedge-wire screens, or other suitable draining mechanism, which remove the majority of entrained liquids, and the materials themselves are discharged by the conveyors onto the collecting pans or troughs of the screen to be hereinafter described. The parting liquid which passes through the wedge-wire screens is returned along the sides of the machine and outside the separating chamber to the charging end of the machine and a continuous circulation is thus maintained. The level of heavy liquid is maintained at any desired point by the adjustable sealed weir at the end of the machine and the level of sealing fluid is maintained by the weir box on the-side of the machine. Continuous addition and removal of liquid through the machine is thus possible, as well as intermittent additions as additions become necessary. Means are provided for blowing out the space beneath the conveyor pans and means are also provided for the removal of sludge from the bottom of the tank.

After the coal has been separated from the indigenous impurities, both are subjected to a vigorous scrubbing. In order to prevent the loss of any liquid by evaporation or otherwise the scrubbing is preferably carried out in a hermetically sealed chamber. A shaker screen is used in order to make possible the thorough washing of the coal, and the problem of transmitting power to the screen without opening the apparatus to the air was no small one. It was accomplished, however, by the means which are more fully described below. Briefly stated, the coal is carried through an hermetically sealed connection from the separating apparatus into the washing section. where, constantly tumbled about by a shaker screen, it is subjected to an extremely tjgOI'OllS washing whereby to remove all fine particles and substantially all the liquids that have been used in the process. The coal and slate are then droppedirom the screen into the water baths of water sealed conveyors. The used liquid is run over a concentrating table, which tends to precipitate suspended solids, and to form large aggregates of suspended liquids, and the whole runs to the tank which forms the bottom of the machine, where a weir divides the liquids which contain only light suspended solids from the heavy sludge. The divisions are respectively drawn oh and treated in a recovery system which will be more completely hereinafter I described.

In the drawings Figures 4 to 4c are illustrative of this portion of the invention. In the figures, d refers generally to the washing apparatus; id is a shaker screen; M is a coal trough form= ing part of the said screen; 32 is a slate trough forming part of the said screen; 53 is a parti tion dividing the screen into two sections 1ongi-- tudinally whereby to keep the separated coal and slate from becoming intermingled. 44 are strips of wood or some similar material which is capa= ble of withstanding the abrasive action of the coal and slate; 45 is a foraminous section at the charging end oi the screen which permits the draining oi liquid; 46 is a wedge-wire screen which forms the floor of that section of the screen which approaches the discharge end; 41 is a solid bottom to the screen at the discharge; 43 are discharge lips.

The construction of the screen is as follows: Angle irons 49 form the side frames of the screen and extend longitudinally from the feeding troughs to the discharge plate 41. Dividing member .49 is also an angle iron extending from the troughs to the pipe; 400 are angle members connecting the side frames of the machine to the main frame of the screen; 401-401 are J-shaped members having the taller leg of the J of considerable height; 402-402 are braces connecting the frame member 43 with the lower portions of the J-shaped member; 403 is a brace directly connecting the two J-shaped members; 404 is a splash guard running the lengtlaof the foraminous portion of the screen.

405-405 represent the support for the entire washing section; 409 is a tank forming the base of the machine; 401 is one wall of the tank;

400-408 are angle-shaped members forming channels with 401 and 416 respectively running lengthwise of and within the

wall

401 and 416; 400 is the inclined bottom of the tank; 410 is a wall of the tank running lengthwise of the apparatus and forming a weir which divides the tank into two sections; 411 is the bottom of the tank beyond the weir; 412 is the outer wall of the tank, in this case placed considerably beyond the outer wall of the screen section; 413 is the top of the said extended side; 414 is a rectangular opening, channel-shaped in cross-section, forming a seat for cover 415. By filling the channelshaped member partly with water an effective gas seal is created. 416 is a wall forming in part the outer wallof theapparatus and in part a wall dividing the two compartments of the tank; 411 are braces attached on the inside to channels 408; 418 is a bar supported by braces 411; 419 are side plates extending lengthwise one on each side of the apparatus; 421 are side plates attached to the braces 402-403 running lengthwise on each side of the apparatus and overlapping the upright portions of channel members 408 inwardly thereof; 42% are drain guards attached to members 419 to prevent the drainage from the screen from running into the channels 400; 422 are drain guards attached to the walls of the screen chamber and projecting within the channels formed at the edges of the screen by angle members 49 and J-shaped members 401-401; 423-423 are walls of the screen section of the apparatus; 424 is the top of the apparatus 425 is a cover for an opening in the top of the apparatus, said cover being formed with one continuous flange 426; 421 are continuous channels in the top of the apparatus of size such that the continuous flange of the top 425 may be seated in the'channel which, being partly filled with liquid forms an effective hermetical seal. 120-420 are supports attached to and projecting at right angles to the outer legs of the J-shaped members; 429-429 are wooden spring boards; 430 are beams to which the spring boards are bolted; 431-431 are spring boards suspended from the beams 430; 432 are weights hung from the said spring boards; 498-438 are guides mounted on the frame 405:01 the apparatus; 434-434 are bufler members approaching the counterweights; 435 is a shaft journaled in the frame 405 436 is a wheel capable of being driven by a belt or similar power-transmitting means and, being keyed'to the shaft 435, capable of driving the said shaft; 431-431 are eccentrics; 430-438 are driving rods attached to the eccentrics 431 and attached through connections 439 to the J-shaped screen frames; 440 are eccentrics placed on the shaft opposite to eccentrics 431 and on the outer sides of the frames 405 respectively; 441-441 are driving rods connecting the eccentrics to the 'counterweights 432. The eccentricsrframe, and driving gear at the discharge end of the machine are shown broken away to indicate that in practice they are farther from the tank than was permitted to be shown in the drawings.

442-442 are headers which may be suspended from the beams 430 by connections 443 which comprise a band encircling the header having a hook to pierce an eye on a middle strip conne'cted to the beams 430; 444 are pipes con; nected to the headers entering the washing tank 'through hermetical seals 445; 449 are valves in the pipes 444; 441 are pressure gauges opera tively connected'to the pipes 444; 443 are pipes connected horizontally to pipes 444; 449 are spray nozzles aflixed to pipes 440 so that the liquid in pipes 448 may be directed at the most efficient angle upon the material on screen 40; 450 are supports attached to the tank at spaced intervals; 451 are bailie plates supported by supports 450 extending transversely of the tank; 452 are channels at the bottom of the baille to catch the drip and direct it to the sides of the screen into the channels formed by angles 49 and sides 401 of the frame; 453 are a series of supports extending transversely between walls 401-416 of the machine and inclined with respect to the horizontal; 454 is a plate supported on supports 4%, extending substantially thefull length of 416 and wall 401 and which have inclination opposite to that of supports 453; 456 is a riiiie plate substantially co-extensive with the length of the machine and extending from the wall 416 to a line short of the wall 401.

In Figure 4a the screen in broken away at 454 to show the plain inclined plate 454; at 456 on the same figure the screen and plate 454 are broken away to show the riiile plate 456 and the diagonal placement of the riiiie bars. .451 is an outlet at the bottom of the tank 406 and at the juncture of incline plate 409 and weir 410; 458 is a pipe opening out of the portion of the tank beyond the weir; 459 is a blow-out pipe through which water under pressure can be directed to discharge the sludge from the bottom of the tank through the orifices 451; 460 is a baiiie plate at the end of the channel formed by

members

49 and 401; 451 is a. channel cut through members 49-49 so that any fluid in said channel member may be discharged upon the surface of and pass through a foraminous portion of the screen; 462 is a boot beneath the discharge end 41 of the screen, separated from the tank as shown in Figure 4 and divided at its center by partition 4161:"e which prevents the mingling of coal and s a In Figure 4e is shown the placement of the spray nozzles so that a double overlap of spraying water occurs. By this arrangement the plugging 0; failure of one spray will not-aifect the washing of the coal because the two adjoining sprays will still overlap.

The operation of the apparatus which has just been described, considered in some detail, is as follows: C083 is discharged from the float conveyor of the separator onto the receiving pan- 4| and slate is discharged from the sink conveyor onto the receiving pan 42. The longerleg of the J -.shaped screen frames is, from the receiving to the discharge end of the screen, of decreasing height, whereas the shorter leg, that which is attached to the spring boards, is of uniform height. As a consequence, spring boards of uniform length are used and the screen is held on an angle. The screen is divided at its mid-portion by a partion which prevents the separated coal and slate from mingling. The driving mechanism reciprocates the screen at a rate which is consistent with the best performance and the materials are moved gradually from the receiving to the discharge end while being vigorously sprayed by a multitude of showers.- The motion of the screen in combination with the sprays turns the coal repeatedly over so that all sides are exposed to, and thoroughly washed with, the cleansing liquid, eifectuating a substantially complete removal of the liquid which the material has carried with it, In order to prevent the each particleof coal is ordinarily sprayed by the water from three nozzles.

The receiving pans 4l42 of the screen are solid, thereafter the screen becomes foraminous either by the punching of holes through the plate, by the use of ordinary screens, or by other means. The final section of the screen is made of wedgewire in order to drain from the coal and refuse substantially all entrained water before delivery to the discharge pans 41 and the divided boot 462. The screen could be all of one type of wire but the arrangement shown produces superior results, all factors considered. Water is preferably used for washing the material and it is forced under pressure into headers 442 from whence it. travels through the depending pipes to the spray pipes 448 and through the nozzles 449. The velocity of the spray is such that a considerable portion of the fluid is splashed from the material or the screen. The direction of the sprays would build up air currents passing from the receiving to the discharge end of the apparatus and considerable quantities of spray, con taining recoverable liquid, would pass over the 1 screen and down into the divided boot where it vwould be lost and contaminate the coal. To prevent this, baiiie plates 45! are attached before each spray pipe so that the mist from the preceding spray will be caughi upon the face of the coal and slate, all below a certain size passing through the screens with the wash liquid.

When the liquids with entrained solids pass through the screens, they are prevented from reaching the sides of the tank by bailies 404,

plates

9, 420, 42i and 408. It will be observed that plates m, which are rigid with the frame of the machine, have openings through which pass the bars 403-402 of the.screen, the openings in the wall of plate 9 being of size to per mit the reciprocating motion of the screen. To prevent the discharge of liquid through that opening into the seal the plates 42!, of a size .adequate to cover the said openings in all positions of the screen, are mounted on the rods 402-403 and abaffle plate 420 deflects any fluid flowing down the side'ofplate 9 over and beyond the said plate 42L All liquid which passes through the screen, consequently, falls upon and runs down the inclination of plate 454, which is a plate having a surface which permits the maximum desirable transportation of the liquid. The plate 454 is terminated short of the side wall and the liquids drop therefrom at substantially the top of rifile plate 456. They run down the said riflle plate, the solids tend to precipitate, the globules of heavy liquid tend to become larger globules so that, when the liquids have finally passed the length of the rifile plate, a partial separation of the constiuents has been effected. The rifile plate is terminated short of the side wall 40'! of the machine and the flow passes over the ends thereof and into the tank 406, all of whose bottom portions slope to the central low point in the neighborhood of outlet 459. The sludge and some parting liquid settle in the vicinity of the opening 451 and the liquid which'carries only comparatively fine particles of solid flows over the weir .4i0 into the other section of the tank, being pumped through orifice 458 to the second settling tank, as is more fully elesewhere here in described. The sludge is pumped through orifice 451 to the third settling tank, which is else where herein more fully described. If the sludge has collected so thickly at the orifice. 451 that the sludge pumps cannot draw it from the tank, a hose may be attached to pipe 459 and water under pressure used to force the sludge out of the chamber.

The screen is counterbalanced by the use of spring board supported counterweights driven by oppositely placed eccentrics from the same shaft. The covers which give admittance to the tank are water sealed by the use of flanged covers which fit water filled channel members in the machine casing.

In order to drive the screen, which is inside the tank, from the driving gear, which is outside, without permitting the escape of vapors, channel members partially filled with water are provided on each side of the machine. The screen frame is made J-shaped, each J projecting into the liquid within the said channels, and being shorter than they by the length of the swing. The'upper portion of the tank is then, so to speak, placed within the hook of the J so that its lower edge is beneath the water level in the channel. The J-shaped frame, consequently, reciprocates within a water seal which effectively prevents the escape of gas, and the previously described construction of the apparatus prevents the contamination of the liquid in the said channels.

From the screen the coal and slate drop into divided boot 462. Giving admittance to this boot are hermetically sealed covers 464. Hermetically attached to the boot on the one side is liquid-tight conveyor box 5| and on the other side a similar conveyor box 52. The boot thus becomes two chutes, one for the coal and one for the slate. A description of one of these conveyors will suffice for both. 5| is the conveyor box in general, being a gas and liquid-tight tank made of metal or other suitable material; 53 is a hopper within the said conveyor tank having an inclined wall 54 to direct the material which falls from the screen into the conveyor box at the angle which offers the least interference with the descending flights of the conveyor; I0 is the inclined underside of the conveyor tank; 5 is a displaced portion of the said side; 5l2 is a foraminous section forming a continuation of the portion of the bottom 5"), the portions 5 and H2 forming between them a space of a capacity adequate to take care of such liquid as may be discharged to them from the solids which are carried out of the tank by the flights; 505 is a conveyor pan; 505 are openings in the lower portion of the conveyor pan; 501 is a section of wedge-wire screen forming the bottom of the said conveyor pan at a point just short of the discharge lip thereof; 58 is the discharge lip of the conveyor pan over which the material is pushed by the conveyor; 59 is the supporting underlip of the conveyor tank; H3 is a flight conveyor; 5 l4 are sprocket wheels over which the conveyor chains are trained; H6 is a motor mounted on the frame 5" of the conveyor; 5l5-5l9- 52l-52l-522-522 are a combined power transmitting and speed reducing agency consisting, in the modification shown, of a series of alternate large and small gears connected either directly or by means of flexible driving means such as chains or ropes. 524 is a wheel driven by means 522 and keyed to shaft 525 on which are keyed the sprocket wheels 5| 4 525 are bearings on the tank which support the rod 525; 521 are parallel bearing blocks; 525 is a shaft iournaled at one end with a loose flt in the said bearing blocks 521 and at its other end in complementary bearing blocks, not shown, at the other side of the conveyor box. 530 is a rod fastened at one end to the shaft 529 and having at its upper end a screw-threaded nut 532;

Ill is a screw-threaded rod making operable screw-threaded contact with the nut 532. One of these rods is attached to each end of the shaft 525. The rods III are mounted on a rod which transverses and is attached to the sides of the tank. The conveyor may jump away from the pan due to the loose fit of the blocks and may be manually adjusted by nuts 582. base of the section 5| I to which is attached a pipe. not shown, connected to the lower section of the conveyor whereby to return the liquid drained from the whole by the wedge-wire screen to the conveyor box at a lower point; 542 is an inlet pipe and valve through which liquid can be run into conveyor box; 5421s an outlet pipe and valve at the bottom of the conveyor which permit the drawing of! of such sludge as may form there. The pipe 542 is connected either to a waste pit or to the settling tank, which is elsewhere herein more fully described. 544 is a liquid box outside of the machine; 545 is an overflow pipe within the said liquid box.

The operation of the apparatus is as follows: Coal is dropped from the discharge lip 48 of the screen through the divided boot and the hopper. The hopper and the conveyor tank are filled to the level 545 with water or other suitable liquid. The coal is discharged into the water therefor above the hopper level and is directed by the inclination 54f is an opening in the of the chute 54 to a place in proximity to the descending flights of the flight conveyor. The coal passes through those flights and directly to the conveyor pan where it is picked up by the ascending flights, drained of liquid by passage over the wedge-wire screens and discharged over the discharge lip 58. The liquid level in the apparatus is kept at the level 545 so that no fumes or liquids coming over the discharge end of the screen will be able to escape into the air. The liquid which is drained through the wedge-wire screen fllls up the space between the conveyor pan and the tank and thereafter passes through the screen 5 into the space below from which it is drained off by pipe 5 which returns it to the bottom of the conveyor tank or elsewhere. Means are provided, not shown in these drawings, for blowing out the space between the conveyor pan and the bottom of the tank and consist of a nozzle through which'water can be forced under pressure at 459 as has hereinbefore been described for other apparatus.

The liquids which wash the coal in the washing section remove from the coal and slate substantially all the heavy liquid and the fine particles which are produced by abrasion or which are carried through the machine. In the settling tank at the bottom of the washing apparatus the liquid with fine suspensoidal matter is separated from the heavy sludge by the weir. The heavy sludge is pumped from the bottom of the tank through pipe 451 to settling tank L'shown in Figures 7 to 70, and the liquid with'light suspensoidal matter is carried through pipe 458 to the main settling tank 6, shown in Figures 6 to 6c.

The system contains three settling or separating tanks interconnected, of which the first, located in the base of the washing section, makes a preliminary division between sludge and liquid containing light suspensoidal matter. the second, called for purposes of difl'erentiation the main settling tank, separates the comparatively light suspensoidal matter from the washing liquid and the third, called for convenience the sludge trap, receives the sludge from both the first and second tanks. The statement has frequently been made in the art that it is impossible to separate coal sludge from washing liquid by any static method. It is believed that the method herein described for accomplishing this result is the only one which has ever been successful.

In Figures 6 to 60 which illustrate the so-called main settling tank or separator, 6 indicates the separating apparatus as a whole; 45! is the discharge end of the pipe which carries the liquid with light suspensoidal matter from the primary settling tank; 5| is the top of the tank; BIO is a tubular member which passes through and flts an opening in the top 8|; 6 is an angle iron which Joins the tube Bill to the top 5| with an hermetical joint. Joining may be by welding or other suitable hermetical sealing. The tubular member extends toward the bottom of the tank. 8I2 are openings in the sides of the tubular member above the operating water line; Bills a cover to thetubular member l0 pierced by the discharge pipe 458; 82 is a truncated conical bottom to the tank; 52l is a sump connected to the truncation of the cone. This sump may be considered to be made by passing a plane diagonally through a cylinder. 622 is the diagonal plane dividing the cylinder" 52l and .forming a diagonal bottom on the sump which directs the 820 and valve 623; 524 is a pipe carrying water under pressure for use in dislodging sludge from the bottom or the sump 62! if and when the said sludge becomes too solid to be moved by pumps; is a rod journaled in bearing 626 in plate 622 and passing through stuifing box 6! 4 in cover H3; see is a handle attached to the upper end of the rod @225; $26 are arms attached toward the bottom oi the rod 625 so as to be rotatable by and with the handle bit and rod 625; 627 are scrapers diagonally placed on the arms 626 so that their movement will dislodge collected sludge from the conical bottom 62 and push it toward the sump 622i; til are water seal covers whose construction is similar to the water seal covers which have been elsewhere herein described; 630 is an angle member of depth which increases from one side of the tank to the other, welded or otherwise connected to the inside of the tank 5 toward the top thereof; tilt is a wooden weir strip of circular form attached to the angle member 636; is a discharge box at the lowest point of the channel formed by tank t and angle member 636; Bit is a pipe connected to the said box $33; 5% is a circular channel suspended from the top ti of the tank within the weir and having a lip Edi which is slightly lower than the top of the weir till; 652 are pipes projecting inwardly from the channel tilt toward the bottom of the tank; are, supports for the tank comprising metal legs attached to the tank and supported upon the box.

The operation of this apparatus is as follows: The liquid containing light suspensoidal matter in greater orless quantities enters the tank through pipette and tube did. it passes outwardly beneath tube did tending to throw toward the bottom the heavier suspensoidai matter and to rise toward the surface, whose level is established by the weir bill. The vibrations caused by the plunge or the water from the pipe 3558 into the body of water in the tank are largely spent within the tube so that the liquid within the remainder of the tank is comparatively quiet. The channel which is formed between the weir and the shell of the tank is sloped and increased in size toward the outlet. The liquid which flows over the weir follows the slope downwardly to the box 633 and is carried by the pipe EH5 back into the headers 442 where it is used again for the washing of the solid materials on thescreen.

Light scum tends to float on the surface of the liquid within the tank and the direction of the liquid currents within the tank would in the normal course wash this scum over the weir. The openings 662 are vents to relieve interior pressure. interposed between the weir and the pipe is the scum gutter d. As the scum, floating on the surface of the water and being drawn by the current toward the weir, floats over the edge 64! of the scum gutter, which is slightly lower than the weir and contacts the side of the scum gutter, the scum tends to precipitate therein. As it is precipitated, its apparent specific gravity increases to the point where it will follow the tubes M2 downwardly into the lower section of the tank where it will settle on the bottom and be drawn' ofi with the sludge. The sludge which concentrates in the bottom is from time to time scraped toward the sump and pumped through valves 623 and pipe 628 to the sludge trap. If the pipe becomesblocked it can be cleared by an injection of water through pipe 626.

In Figures 7 to '70 is shown the arrangement of the sludge trap and the still. The function of the sludge trap is to separate out the water with light suspensoidal matter and return it to the main settling tank for further treatment; secondly to separate out isolated heavy liquid and return it to the heavy liquid storage tank; and thirdly to inject all remaining liquids and solids into a still for the recovery of any parting liquid which may be therein contained.

In those figures, 4 51 and 62!) indicate pipes leading from the first and main settling tanks, respectively. I refers to the sludge trap taken as a whole; It is the pipe through which passes the sludge from pipes 45'! and 620; iii! is a sight glass held in liquid and gas tight relationship between plates Hi and H2; H3 is an inlet pipe of diameter considerably greater than that of II in order that the discharge material may be reduced in velocity and find easy entrance to the sludge trap and not fill up the sight glass Till; lid is a tubular member inside the tank through which the material is discharged; H5 is a water seal covering of the type which has been hereinbefore described; lid is a circular weir within the tank towa'rd the top thereof which forms with the walls of the tank a channel having an inclination sufficient to drain such liquids as pass over the weir to the discharge box 'ii'i; ml is a circular baffie plate within the weir. The lower edge of the heme plate is beneath the liquid level in the apparatus, and in close proximity to the weir so as to form a substantially complete vapor seal. HQ are a series of valved openings leading into the tank at various levels; l'Zii is a header connecting the said valved openings; -'i2i is a drawoff pipe leading from the header; i2?! is a glass peep slot through which the contents of the tank may be observed substantially throughout its height; 123 is a pipe mounted in the side of the tank; 726 is a section at right-angles thereto; M5 is a liquid-tight ball joint; #26 is a section of pipe movably connected to section 62d through elbow I21 and ball-joint 125; I28 is a block attached by rod 729 to pipe 126 and through connection 130 to rod i3i which passes through a stuiilng box in the top of the tank; rod i3! is attached to a slider E32 operably mounted for vertical sliding movement between guides 133- 133; 13 i is a rack affixed to the face of slider I32; 135 is a pinion mounted on rod 136 which is journaled in bearings 13! which are mounted on the supports 138 which are attached to the tank; 139 is a wheel, chain or otherwise operated, which is attached to shaft 136. By rotation of the wheel 139 the rod 13! may be raised or lowered, raising or lowering the pipe 126 in conformity; H0 is a conical bottom to the tank; 14! is a valve in pipes 142 which connects the sludge tank with the still 8; I43 are supports for the tank.

The operation of the apparatus which has just been described is as follows: "The sludge from the sources of sludge supply is brought through the sight vfeed glass H0 and pipe H3 into thetank where the sludge settles to the bottom, the heavy liquid forms alayer on top of the sludge, and water is separated out on top of the heavy liquid. The condition of the ingredients is such that in many cases so clear a. separation is obtained that it is possible to draw ofi part of the liquid by decantation, substantially clear liquid passing over the weir and out through the pipe I l 1 from whence it may be returned to the settling tank, to the main settling tank, or may be discharged. Between the layer of sludge at the bottom and the layer of light liquid at the top there may form a layer of the heavy parting liquid of suflicient purity to be withdrawn for storage or immediate