Патент USA US2293033код для вставки
Aug. 18, 1942. H. 1.. MEAD ETAL '- 2,293,033 API’ARA'I'US AND rnocnss For: mzsnnqne momnon FEED ’ Filed April 5, 1940 ‘ 2 Sheets-Sheet 1 INVENTORS law/FRY 4 . M540 , LOP/V4197‘ u. M4057‘ ATTORNEY. Aug. 18, 1942. I H. L. MEAD EI'AL _ - 2,293,033. APPARATUS AND PROCESS FOR DESLIMING FLOI'ATION FEED Filed April 5, 1940 Z-Sheets-Sheet 2' I y ..x.. . ‘ INVENTORS' H4??? A . M6740 , ‘ATTORNEY. v Patented Aug. '18,‘ 19.42, ' r 2,293,033‘ ‘UNITED? STATES PATENT OFFICE APPARATUS AND rnocsss FOR nasrmmo morarron mans ' ‘ Barry L. Mead and Ernest J. Maust, Brewster, Fla., assignors to American Cyanamid Com pany, New York, N. Y., a corporation of Maine . Application April 5, 1940, Serial No. 327,948 ' 6 Claims. (cpl. 209-454) This invention relates to the desliming of E ?otation feed in the ore dressing art and more _‘ particularly it relates to an improved apparatus of the hindered settling type for desliming the ?nest fraction of ?otation feed. ~ Recent improvements in the ?otation art have required that ?otation feeds be very thoroughly deslimed,v that is to say, more completely than the desliming produced in the use of free settling tanks. This is particularly true inv connection 10 with the ?otation of silica from phosphate rock using the so-called cationic ?otation reagents as even very small quantities of slimehave a dele terious effect on the promoter action of the tion is conducted in one tank where a small amount of water and a small area' does work equivalent to that accomplished by a series of large settling tanks employing much larger quantities of water. This improved apparatus is useful‘i‘or desliming very ?ne ?otation feed of any ore material but it is particularly useful in the non-metallic ?eld, especially the ?nest frac tion of phosphate ?otation feed ranging from -48 mesh down to 325 mesh. In carrying out our invention use is ‘made of the density of a teetering mass of ?ne ?otation feed to keep the light slime from-entering the denser body of material in suspension. A density reagents. ‘ in excess of that of water is induced in the In our copending application Serial No. 320,121 pockets of the hindered settling deslimer due ‘to ?led February 21, 1940, we have described an the particles being held in teeter by means of improved process for the simultaneous sizing and the hydraulic water passing through the con desliming [of phosphate ore ?otation feed in a striction plate in the bottom of the compart hindered settling classi?er, which is a much 20 ment. Hence, in addition to the tendency for more eiiicient method than the ordinarily em a rising column of water to carry off slime, the ployed desliming, operations, the process, how density of the material in suspension also tends ever, deals only with the desliming of the larger to aid in slime removal. In our improved bin particlefractions of the phosphate material and dered‘ settling deslimer water is added at such does not result in slime removal from the very a rate that only about 6 gallons per minute per ?ne fraction of phosphate material to which square foot of over?ow area is used. In the the present invention relates. ‘ _ The ordinary'methods of desliming very'?ne ?otation feed in the past have ,not been found ‘ordinary hindered settling classi?er water in ex cess of this amount must be used to keep the ‘particles in suspension and thus ?ne ?otation to be entirely satisfactory. The prior methods 30 feed-is over?owed. This water limitation at a of desliming very ?ne ore material usually con point of not over about 6 gallonsper minute per sists of passing the material into a series of large square foot of over?ow area is made possible and settling tanks with the addition of large volumes teeter still maintained by ?aring the hydraulic of fresh water to each of the series of settling chamber at a point above the teeter column. tanks. Adequate settling area in this case must 35 It is an advantage of the present invention be provided in each tank to settle all of the plus that the ?nest fraction of phosphate ?otation 250 mesh material each time that it enters a feed which cannot be deslimed ,in the ordinary ‘ tank. As some. slime always tends to settle, hindered settling classi?er (-48 mesh down to with true particle size material, the amount .of 325 mesh) is readily deslimed using our im slimesettling in each tank of \a series is a de 40 proved apparatus. A very thoroughly deslimed creasing amount, but is never entirely removed product is produced, which deslimed feed when as mathematically this is impossible. Hence, subjected to froth ?otation concentration by in previous methods ‘it was not economically either the silica ?otation process or the fatty practical to obtain the high degree of desliming acid phosphate ?otation process results in a that is attained in the hydraulic hindered set 45 higher grade product and permits more e?lcient _ operation. tling deslimer of this invention. The settling tanks of the prior methods might be cylindrical _ ‘The present invention has many advantages tanks with ?at bottoms, conical tanks, or rec tangular tanks with bowl attachments wherein ’ the settled material was raked out of-the bath. _In accordance with the present invention a process is provided in which very ?ne fractions of ?otation feed can be thoroughly deslimed. An over the prior desliming processes such as those using a series. of settling tanks or cones, drag classi?ers and the like. Some of these outstand ing advantages are low ?rst cost of equipment, small floor space. and economy of about 60% to 70% in the use of water over the free set tling desliming. When compared to a desliming improved apparatus of the hindered settling type is provided in which the entire desliming operas .55 process using a series .of these cones it was found ' 2,298,083 2 of the tank is not suf?cient, however, to support that only’ll/a as much water was needed in our improved hindered settling deslimer and at the the ore particles and they fall back into the pock vsame time ‘the initial cost was only about 5/5 as much to produce a better deslimed product. ,The invention will be more readilyunderstood _by referring to the following drawings of our jected to hydraulic water at a velocity di?erent from that in pocket ‘I. This process is repeated improved hindered settling deslimer apparatus in which: Fig. 1 is a longitudinal sectional view; ets. The feed passes from the pocket ‘I into the pocket 8 by means of the slot I5 and ishere sub as the feed passes from pocket to pocket, addi tional quantities of slime being removed in each pocket until the thoroughly deslimed feed col 10 lects in the last pocket I3, from which it is sub Fig. 2 isv a top plan view; and sequently discharged by operation of the dia Fig. 3 is a transverse ‘sectional view taken phragm actuated through the changes of spe along the lines 3-3 of Figs. 1 and 2_and looking ci?c gravity in pocket I2 to open the plumb bob in the direction of the arrows. valve seated in the feed discharge opening I9. ‘ The deslimer comprises atank I having the is no opening in the ba?le I4 separating ?aring sides 2. The lower half 01' the tank is 15 There pocket I2 from pocket I3 and the velocity of the divided into a plurality of pockets or compart hydraulic water in I3 is just enough less than ments as illustrated. These pockets are num that of pocket I2 so that the feed passing over bered from ‘I to I3 inclusive. A hydraulic water the top of baille It into pocket I3 will settle or. compartment 3 is located beneath the pockets collect at the bottom. 20 and separated therefrom by the perforated con We have found that a very ?ne fraction of. striction plate 4 through which hydraulic water phosphate ?otation feed can be very thoroughly may be ?owed. Any number of pockets may be deslimed in accordance with the above operation, used, the number being optional and limited only by which even the 250 mesh material may be to a practical size over which water may be uni retained using an apparatus in which approxi formly distributed through'the holes of the con- mately 2000 gallons per minute for 50 long tons striction plate in the hydraulic water compart per hour of feed were being processed. Among ment 3. Hydraulic water inlets 22 are shown the important features which appear to be in a leading into the various portions of the hydraulic general measure responsible for the improved re water compartments 3 in such a manner that of this apparatus are the ?ared sides of varying amounts of water and at different veloci 30 sults the tank which increase the area‘ and reduce the ties may be forced through the constriction plate velocity of the uprising currents of water so 6 into each oi‘ the pockets ‘I to I3 inclusive. A that the slimes are carried over the top and the baiile plate I4 divides each of the pockets from ore materials fall back and can be collected. the adjoining pockets from ‘I to I2 inclusive. All By restricting the over?ow at a point where of the pockets except I3 are connected through a . = the material is to be removed, we provide a suitable opening or slot I5 in the battles I4. While positive ?ow of a small amount of remaining the slot I5 is shown extending only part way up slime in a direction opposite to that of the pas the ba?les I4, it may, if desired, be extended to sage of feed. This is an important part of the the top. A standpipe I1 is shown positioned in invention. Another important part of this in the pocket I2, in such a manner that changes vention is the restricting of the ?ow rate of of speci?c gravity in this compartment cause water- in the cell in which the material is dis water to rise in the pipe actuating a diaphragm 20 operatively connected to the top of the stand pipe. This diaphragm may be 'of the ordinary ?exible‘ rubber type but is preferably a bellows diaphragm. When the diaphragm is forced up wardly by water pressure the plumb bob valve I8 which is seated in the discharge opening IS in the bottom of pocket I3 is raised a su?icient height to permit the deslimed feed to pass out through the opening I9. Each of the pockets ‘I to I3 inclusive may for convenience have obser vation windows 23 which will permit the oper ' charged to a point low enough to settle all 01 ' the plus 250 mesh ?otation feed. As water is added in excess of this amount in the other cells, limiting the velocity of upward ?ow to a point below 6 gallons per minute per square foot of over?ow area at the over?ow point, the ?nest of the ?otation feed could not settle into the bot tom of these pockets to be discharged. Hence, in the pocket through which the material is dis charged the velocity of the rising current of water is maintained at a point below 6 gallons per min ute per square foot of area. As the ?ne ma ator to view the passage of the feed through these compartments. A feed opening 2I is so 55 terial is not agitated suf?ciently at this low ?ow rate to actuate a diaphragm discharge mecha arranged in conjunction with the baf?e I6 that nism, this mechanism is operated from the super when feed is introduced it passes directly into elevation water in the adjoining pocket to dis the compartment 1. An over?ow area at the charge the deslimed‘feed in the discharge com top of the flared portion of tank 2 is provided by means of the weir 5 by which water and‘ slime 60 In a preferred embodiment of our apparatus a are over?owed into the over?ow launder 6. The diaphragm actuated device working through su weir 2| prevents over?ow at the most distant perelevation of the material in teeter in a pocket portion of the tank from the feed entrance. In operation a very fine ?otation feed, as for of the machine to discharge the material, from partment. ' _ . example in the case of phosphaterock ranging an adjoining pocket is employed. The deslimed in particle size from —48 to 325 mesh, is fed into feed might also be discharged by means of a the feed opening 2I and thence into the com hand operated valve, a centrifugal pump or a partment ‘I, whereupon the rising currents of simple spigot, without violating the basic fea hydraulic water passing through the construc tures of the‘ invention. ,There are many ad tion plate .4 carry the ?ner slime particles into 70 vantages however, which result from the use of the ?ared portion of the tank. Here the up ‘the teeter column .actuated diaphragm pump, ward velocity of the water decreases due to the among which are: it is automatic in operation increased area. The velocity is, however, sum and does-not require the attention or an oper cient to carry the slimy Particles over the weir 5. ator, it is easily adjusted for any variance in the The velocity of the water in the ?ared portion 75 2,293,033 type of feed, amount of feed or other operating conditions. - . In utilizing our improved apparatus no sizing is attempted unless we differentiate between col loidal slime and true particle size of about‘250 mesh. The rising velocity of the hydraulic water is regulated in‘ such a manner that it is su?icient to ?oat away the colloidal slimes while at the same time it is approximately equal .to or less than the free settling rate of 250 mesh sand. When the velocity of the rising water is thus regulated the 260 mesh sand and, ofcourse, the material "larger than 250 mesh readily separates out and is completely free from the colloidal slimes. _ > We claim: 1. A-method of desllming withoutclassifying slimy ore feed containing ?ne particle sizes which comprises introducing the feed into a rising col umn of water the velocity of said rising column being such as to cause the coarsest particles of the feed to remain in suspension, subjecting said stream of water to deceleration to a velocity at which the ?nest ore particles settle but slime rises, over?owing a portion of the water at said velocity to remove slime, causing said deslimed materials to pass into a zone of rising water the tank-the upper portion of which has ?ared sides ‘and an overflow area for slimes, a series of pockets located in the lower portion of the tank, means for introducingyore material into one of the pockets, means for discharging the coarser ore material in a pocket located at the opposite end of the series from the one into which the feed is introduced, means for introducing water upwardly into each of the pockets at a variable velocity, means for restricting over?ow above the pocket from which the deslimed feed is dis charged which causes the excess water to flow in a direction opposite to that of the passage of feed water in order to over?ow from the tank, said pockets in the series communicating with one another through‘ restricted openings in the ‘sides thereof with the exception that there is no communicating opening in the wall of the discharge pocket‘ and the preceding'pocket. 5. A hindered settling deslimer comprising a tank‘ the upper portion of which has ?ared sides and, an over?ow area for slimes,'a series of pockets located in the lower portion of the tank and having perforated bottoms, means for intro ducing ore material into one of the‘ pockets, means for discharging the coarser ore material in a ‘pocket located at the opposite end of the velocity of which‘is such that the particles just series from the one into which the feed is intro duced, means for introducing water through the settle in ‘a discharge zone and discharging the settled ore particles from said discharge zone at 30 aforesaid perforated bottoms into each of the a rate determined by sensing means located in a ~ ' zone 'preceding the discharge zone. a 2. A method of desliming without classifying slimy phosphate ore feed containing very ?ne pockets at a variable velocity, means for restrict ing over?ow above the pocket from which the deslimedieed is dischargedv which causes the excess water to ?ow in a direction opposite to particle sizes, which comprises introducing the 35 that of the passage of feed water in order to feed into a rising column of water the‘ velocity over?ow from the tank, said pockets in the series communicating. with one another through of said rising column being such to cause the restricted openings in the sides thereof with the coarsest particles of the feed to remain in sus exception that there is no communicating open-‘ pension, subjecting said stream of water to de celeration to a velocity at which the ?nest ore 40 ing in the wall of the discharge pocket and the' preceding pocket. ‘ particles settle but slime rises, overflowing a por 6._ A hindered settling deslimer comprising a , tion of the water at said velocity to remove slime, tank the upper portion of which has ?ared sides causing said deslimedmaterial to pass into a zone and an overflow area for slimes, a series of of rising water the velocity of which is such that the ?nest ore particles just settle in a discharge 45 pockets located in the lower portion of the tank and having perforated bottoms, means for in zone and discharging the settled ore particles troducing ore material into one of the pockets, from said discharge zone at a rate determined by sensing means located in a zone preceding the means for- discharging the coarser ore material a diaphragm mechanism discharge zone. , which; comprises 3. A method of desliming without classifying 50 actuated by density changes‘ in one pocket to operate a feed discharge opening in the bottom slimy phosphate ore feed containing very fine particle sizes, ranging from ~48 to+325 mesh ot another pocket located at the opposite end which comprises introducing the feed into a ris of the series from the one into which the feed is introduced, means for introducing water ing column of water the velocity of said rising column being such to cause the coarsest particles 55 through the aforesaid perforated bottoms into each of the pockets at a variable velocity, means of the feed to remain in suspension,‘ subjecting for restricting over?ow above the pocket from v said stream of water to decelartion to a'velocity which the deslimed feed is discharged which at whichthe ?nest ore particles settle but slime causes the excess water to ?ow in a direction op rises, over?owing a porion of the water at said velocity to remove slime, causing said deslimed 60 posite to that of the passage of feed water in order to overflow from the tank, said pockets material to pass into a zone of rising water the \ velocity of which is such that the ?nest ore, 250 mesh, particles just settle in a, discharge zone in the series communicating with one another vthrough restricted openings in the sides thereof and discharging the settled ore particles from with the exception that there is no communicat said discharge zone at a rate determined by sens-‘ 65 ing opening in the wall of the discharge pocket and the preceding pocket. ing means located in a zone preceding the dis charge zone. . - 4. A hindered settling deslimer comprising a . ' _ HARRY L. MEAD. ERNEST J. MAUST.