US2670078A - Method and apparatus for separating and drying comminuted solids - Google Patents

Description

Feb. 23, 1954 N, L .'DAvls 2,670,078

METHOD AND APPARATUS FOR SEPARATING AND DRYING COMMINUTED SOLIDS Filed Jan. 12, 1949 2 Sheets-Sheet l l Il lo Feb. 23, 1954 2,670,078

N. L. A DAVIS METHOD AND APPARATUS FOR SEPARATING AND DRYING COMMINUTED SOLIDS Filed Jan. 12, 1949 2 Sheets-Sheet 2 Patented Feb. 23, 1954 METHOD AND APPARATUS FOR SEPARAT- ING AND DRYING COMMI-NUTED S'OLIDSI Nelson L. Davis, Chicago, Ill.

Application January'l, 1949, Serial N c. 70,471

My invention relates to improvements in float and sink separation and drying oi? solid materials and has for one object to provide anappara'tus and process which may be used for' the separation or cleaning and drying of. coal, ore and the like, by means of a high volatile heavy liquid medium.

Another object of my invention is to provide afloat andvs'ink processv and apparatus wherein the'heavy medium liquid used in the float and sink process is entirely contained within thevsystem and is recirculated in an enclosed apparatus and system without ycontamination by outside air.

Another object of rnyinvention is to provide a process and apparatus wherein moist or wet coal-or ore may be by one single continuous process and in one single apparatus separated according to `different specific gravities and dried or freed from water.

Other objects will appear from time to time throughout the -specication and claims.

My invention is illustrated more or less diagrammatically in the accompanying drawing, wherein:

Figure l is a vertical longitudinal section;

Figure i2 is a section along the line 2-2 of Figure l; and I 'Figure 3 is a sectionalong the line '3 3 of Figure'l.

Like pa-rts are indicated by like characters'4 throughout the specilication land drawing.

-The heavy medium thatI propose to use vis a high volatile chemical liquid such as chlorinated hydrocarbon which has toxic or poisonous characteristics and it is essential therefore that the medium be so handled that vit never escapes from the system 'and that both `the iioat and sink material, when vdischarged from the iioat and sinkvessel, becompletely'freed of the heavy medium.

'This medium is heavier than water. y It is immiscible with water -and whenfsolids wet with Water 'are immersed in a bath `oi the heavy medium, the waterfloats to the top of theheavy medium bath and forms a layer of' water supernatant on'the heavy mediumbath. A Most if 'not all of the water associated with the solidsfwill be-i'epla'ced by the heavy .medium'and 4forced upwardly through the heavy medium 4bath and asolids retaining screen to join the supernatant water layer.

'it is'a'i'loat and' sink'vessel' having atfthebottom a. vscrew conveyor i2 extending 4longitudinally thereof and above the ibottom but blow .the top v7 claims. (o1. 209-172) screw conveyor 3 extending longitudinally thereof. 4 is a .cover for the vessel. 5 indicates, .as will hereinafter appear, the level of the heavy parting liquid. 6 isa screen extending across the vessel, furnishing a housing for the screw conveyors 3, which conveyors closely fit the screen.

with liquid discharge vtroughs 8, the weirsand troughs being also enclosed A'by the coverll. 9 is an .annular refuse boot into which the refuse conveyor .2 discharges. Theiboot contains .an elevating bucket wheel, the buckets i0 of which are perforate. The boot B'communicates above the vvessel cover 4 with .a refuse conveyor .trough H 'in which is a refuse screw conveyor |72. i3 is a cover for the trough Il and the voutboard end of the-trough Il discharges into achute M and 4thence into a refuse belt conveyor i5. IB is an yannular boot communicating `with the vessel l, there being an aperture between them so thatthe screw conveyors .3 `discharge into the boot I6. The boot lr6 contains an elevating bucket wheel having perforate buckets l1 yadapted todischarge intoftroughs i8 .containing screw conveyors |9,.the .trough It being closed .bye cover 20. The screw conveyors I9 discharge through fa chute 2| onto a fbelt, conveyorV 22.r 23 is a feed trough extending laterally from the feedend of 'the vessel l. Thescrew conveyors 3 extend 'outwardly `from `the vessel intothefeed trough. The Vfeed ytrough is .closed vat .24 and communicates with a feed hopper ,25, which in turn receives the feed ythrough a .chuteZ .227 serves .asa coverfor .the chute 2E. and hopper 25. 28 is a Weir box which receivesoveriiow 'from the troughs 58 `and :discharges 'through `thegpipe 29..

30 `indicates similar pipes vforming part of 1.a

steam heating system, the detailsof .which v,are not shown but which communicate `with "steam jackets f3l, `32 Aabout the "troughs Il and i8 iso.

'l indicates weir's formed by the upper edges of the vessel walls which are associated i which contains the condenser coils and spent cooling water is discharged through the pipe 54. Pipe 55 leads from the upper portion of the condenser to the trough il and the pipe 56 to the trough IB.

SEI is a pipe joining the feed hopper 25 and the vessel I above the heavy medium level.

It will be realized that whereas I have illustrated and described an operative device, still many changes might be made in the size, shape, number and disposition of parts without departing materially from the spirit of my invention. I wish, therefore, that my showing be taken as 1n a broad sense as diagrammatic and illustrative rather than limiting me to the precise showing.

The use and operation of my invention are as follows:

The vessel is rst filled with the heavy medmm to the level approximately as indicated at E. Under these circumstances the heavy medium will stand at the same level in the vessel in the two conveyor boots 9 and IB and in the feed hopper 25. Water will then be added to cover the heavy medium with a continuous sheet of water. This water level will be equaliaed through the pipe SB in the vessel and in the feed hopper 25 but since the level of the heavy medium was above the openings between the vessel and the two boots, no water will enter them but the level of the heavy medium will rise in both boots a distance sufiicient to compensate for the added pressure made by the water in the system.

The solids to be treated which for example might well be coal with mixed refuse, slate bone, etc. and which normally have a substantial amount of adhering water, will be introduced into the feed hopper. Some of the solids will sink to the bottom of the hopper, other of the solids will tend to float. The screw conveyors will operate to propel the solids from the feed hopper into the vessel. The continuing supply of solids into the feed hopper will insure the downward movement of both sink and float material to bring it into the range of operation of the screw conveyor. Some of the adhering water will be forced upwardly as the material is immersed in the heavy liquid and there will be a gradual increase of the amount of water in the system as a result of the continuous introduction of water laden solids. As the solids are fed into the vessel, the heavy material will sink to the bottom while the lighter material will flow up. Its upward movement will be limited by the screen troughs which enclose the upper portions of the screw conveyors 3 and so the float material will be propelled across the tank bel-ow the level of the heavy medium and out of contact with the water. The sink material will be propelled in the opposite direction by the conveyor 2. The conveyors will agitate the heavy medium and the solids therein contained suiciently to permit a continuous upward movement of the water through the heavy medium through the screen to join the supernatant water layer. As the process continues, the vessel will fill until the water is discharged over the weirs 'i from the system and such water will continue to be discharged at the same rate as it is introduced with the solids.

The solids will continuously be discharged by the screw rconveyors 2 and 3, the sink material going into the boot S, the float material into the boot I5. The bucket wheels will raise this material above the levelof the heavy medium and altogether out of contact with the water. Because the buckets are perforate, f most of the heavy medium will drain off as the bucket wheel elevates the material above the level of the heavy medium so that both the coal and the refuse when discharged into the troughs ii or i8 as the case may be, will be generally free of heavy medium except for that relatively small amount adhering to the surface of the solids.

The solids with whatever heavy medium is left adhering to them will be propelled through the troughs il and I8. The temperature of these troughs and the material contained therein is raised by the steam jackets 3l and 32 high enough to vaporize the heavy medium and so both refuse and coal is discharged from the troughs in a dry, liquid free, condition.

The drying zones defined by these heated troughs are illustrated as being separate but of course there is no reason why the screw conveyors could not all of them, if desired, be closed in a single housing and forming a single drying zone.

The solids propelled through these drying zones is thus free from heavy medium. It it should happen that some of the water has not been entirely removed from the solids, if an occasional entrapment of water by solids during the passage of heavy medium should occur, such entrapment will be very limited and the temperature in the drying or vaporizing zone will be such as to tend to vaporize some if not all of such small amoun of water.

The vaporized heavy medium will of course be mixed with a certain amount of air and perhaps with a certain amount of water vapor and this vapor and air will be drawn up from the heating zone through the blower into the condenser. There the heavy medium will be condensed and the heavy medium and perhaps some water will be returned to the vessel above the level of the heavy medium. If any water is so returned, it will remain in the supernatant water layer while the heavy medium sinks to its level, and thus do no harm.

In order that the blower may not by any chance draw against the vacuum in the heating zones, the air which is returned from the condenser as indicated by pipes and 55 returns freely to the vaporizing zones.

This process and apparatus is directed primarily toward the treatment of fine coal and refuse. If any of the coal, that is any of the oat material is small enough to pass upwardly through the screen, it will be mixed with the water as it rises above the level of the heavy medium and will ultimately be discharged over the Weir with the water and may be wasted, or recovered by conventional methods.

Another problem, however, rises in connection with the lines which iioat and that is the danger that they might clog the screen. That danger is minimized by the fact that the screw conveyors immediately beneath the screen set up a zone of agitation suflicient to prevent such clogging, thus if necessary, other means might be used for occasionally freeing the screen or cleaning it.

I have shown screw conveyors and bucket wheel elevators. Other conveying means and other elevating means might be used.

Under some circumstances it might be desirable to have partitions or guides or broken flights Xed in the space between the buckets and the point where they receive the discharge from the screw conveyors to insure a sufcient movement or agitation of the heavy medium and the solids supported therein. Under ordinary 7 .float and sink components from the vessel, at a point below the level of the parting liquid.

4. A mineral separating apparatus including a vessel adapted to contain a bath of heavy parting liquid, means for maintaining a layer of water at generally constant level iioating on the parting liquid, means for introducing solids to be separated including both float material lighter than the parting liquid and sink .material heavier than the parting liquid into the vessel at a point below the level of the parting liquid, means for preventing the rise of the float material to the level ofthe parting liquid, means for propelling the float component across the vessel beneath and in engagement with the means for preventing the rise of the ioat material, means for separately propelling the sink component alongr `the bottom of the vessel, means for separately withdrawing the iioat and sink components from the vessel, at a point below the level of the parting liquid.

5. A mineral separation apparatus including a vessel, a cover therefor, a feed hopper, two connections between the hopper and the vessel, one above the other, a bath of heavy parting liquid adapted to be contained within the vessel and hopper, the level of the parting liquid being between the two connections between the bath and hopper, means for maintaining a liquid sealwith in the hopper and the vessel comprising a supernatant layer of water on the bath the level ci which is above the level of the upper connec tion, an elevator boot communicating with the `vessel 'below the level of the heavy liquid bath, a vaporizing chamber, means for heating it to 'vaporize the liquid, a closed passage leading from the boot to the chamber, means for propelling material through the boot, the passage and the vaporizing chamber and for discharging dried material from the system, a cover for vthe vaporn izing chamber, a condenser, means for drawing vapor from the chamber to and through the con denser to condense it, means for discharging condensed vapor in liquid form to the bath.

6. A mineral separation apparatus including a vessel, a cover therefor, a feed hopper, two conu hopper, means for maintaining a liquid seal within the hopper and the vessel comprising a supernatant layer of water on the bath the level oi' which is above the level of the upper connection, an elevator boot communicating with the vessel below the level of the heavy liquid bath, a vaporicing chamber, means for heating it to vaporize the liquid, a closed passage leading from the boot to the` chamber, means for propelling material through the boot, the passage and the vaporizing chamber and for discharging dried material from the system, a cover for the vaporizing chamber, a condenser, means for drawing vapor from the chamber to and through the condenser to condense it, means for discharging condensed vapor in liquid form to the bath, means for returning gas and air from the condenser to the vaporizing zone, .means for withdrawing vapor from the feeding hopper and from the solids discharge to the condenser.

'1. The method of separating and removing water from mixed sink and float solids, which consists in immersing them in a bath of liquid heavier than, immiscible with, and more readily vaporized than water, the specific gravity of which is greater than that of some and less than that of 'other of the solids, permitting the sink material to descend to the bottom of the bath while positively holding the float solids below the level of the heavy liquid, conveying the solids through the bath below the level of the heavy liquid in a continuous moving layer, agitating that layer of material to promote sink and float separation and to promote` adherent water to pass upwardly through the bath, withdrawing the solids from the bath and separately withdrawing supernatant water from the surface of the bath.

NELSON L. DAVIS.

gesamtes cited in the fue of this patent UNITED STATES PATENTS

Images