US2416066A - Froth flotation cell - Google Patents

Description

Feb. 18

D. S. PHELPS FROTH FLOTATION CELL Filed May 1944 s sheets-sheet 1 mill:

v INVENTOR.

Jana/d 5. fkl/fla BY /(M Feb. 18, 1947. p. s. PHELPS 'FROTH FLOTATION' CELL Filed May 19, 1944 3 Sheets-Sheet 2 I mmvron Jana/d J fiz/ .s W5 Kat V F b. 1'8, 1947. D. s. PHELPS 2,416,066-

FROTH FLOTATION CELL Filed May 19, 1944 3 Sheets-Sheet 3 INVENTOR.

Patented Feb. 18, 1947 Donald S. Phelps, Harvard, Mass.

Application May 19, 1944. Serial N0. 536,230

3 Claims. (Cl. 209-168) This invention relates to froth flotation apparatus, and more particularly to improving the aeration and separation of values from pulp.

It is an object of the' invention to improve the I aeration of pulp by causing pulp to be discharged in the open air and directed against a body of pulp at a relatively high velocity whereby air is entrained and froth is produced. r

Another object of the invention is to provide a frothing cell capable of subjecting all of its contained pulp to circulation and aeration so that the material not entrained in the froth is afforded recurring opportunity to be directed to the froth and recovered as concentrate. This results in the thorough mixing of air and pulp and recovery of coarse particles which otherwise would be lost.

Another object of the invention is to provide a frothing cell wherein a froth forming portion is localized in symmetrical relation to the frothoverflow lip of the cell and the cell functions automatically to direct the generated froth outstrated by the drawings which show by way of illustration a preferred embodiment and the principle of my invention and what I now consider the best mode in which I have contemplated applying that principle. Other embodiments of the invention employing the same principle may be used and structural changes made as desired by those skilled in the art within the spirit of the appended claims and without departing from the present invention.

In the drawings,

Fig. 1 illustrates a vertical section of a unit employing my invention.

Fig. 2 is a plan-of the unit illustrated in Fig. 1.

Fig. 3 is a section on line 3-3 of Fig. 2.

Fig. 4 is a section on line 4-4 of Fig. l.

Fig. 5 is a vertical section of a modified form of unit.

Fig. 6 shows a schematic arrangement of a battery of cells.

A froth flotation unit or cell embodying the principle of my invention includes a, tank ill, a pump II and conduit connections l2, 13, whereby pulp is conducted from the tank to a header l4.

2 A motor l5 or other source of power is provided for driving the pump.

I preferably employ a tank having a conical wall which merges into pipe I! connected to the lower portion of the tank and to the intake side of a pump. "While the upper portion of the tank may be variously shaped, a circular flotation area has advantages which will appear in more detail hereinafter.

'I'he pulverized ore. whichmay or may not have been previously treated with oil or other agent, is mixed with water and any desired flotation agent to form a pulp in the usual manner. The

pulp is contained in tank I0 and the froth is produced by circulating the pulp through the pump ll, conduit l3 and header l4 and by directing it against the pulp in tank l0.

The'header is disposed above the pulp level so that it will discharge through the air.

of orifices in the form of spray nozzles l6 whereby the pulp is projected from the header in a number of streams. The streams are projected at a relatively high velocity and in their travel from the header to the surface of the pulp in the tank, air is entrained and froth is produced.

The size of the header and the number and' to cause their streams to focus on one point, and whether the sprays are parallel or angular to each other, other instrumentalities such as one or more deflecting surfaces can be used, if desired, to cause greater agitation and consequent aeration.

In order to minimize friction loss because of the header the total discharge area of the several Y lent to a three-quarter inch pipe, but the discharge velocity may be increased for any given size of discharge pipe by providing spray nozzles As shown in Fig. 1, the header is provided with a plurality zles, with the result that 3' tained in the header and a higher velocity head ensues. A sufliciently high velocity head should 1 be maintained, whatever the number of sprays,

For a unit having 9.4-inch discharge pipe, six

1 teen 1-inch sprays will produce a desired aeration of a given pulp and if it is desired to increase the amount of entrained air, such result can be attained by changing the header to one having, say, twenty-eight A-inch sprays. 1 larger the number of sprays the greater the aeration. The use of more nozzles for discharging the 3 same quantity of pulp In general, the

has the effect of increasing friction head due to the increased circumferential surface area of the greater number of nozgreater pressure is mainin order to obtain a high emission velocity with consequent high entrainment of air. The friction head due to the spray nozzles need not be large because of their short lengths. It is an advantage of the present invention that the static head upon the pump is relatively low since no great lift of pulp is required.

.As illustrated in the drawings, the locus of impact of the sprays upon the pulp contained in the tank is localized by a baffle 20-which extends from above the'level of the pulp and sufliciently below its surface to avoid agitation of the pulp outside of the zone of impact of the sprays. The exact location of the lower edge of the baffle depends upon the velocity of discharge through the nozzles and somewhat on the quantity of their discharge.

A sleeve is suitable for use as a baflle and this may be supported on brackets such as 2l, 22, 23'

and 24. Provision may be made to adjust the baffle to change the height of its lower edge.

The froth formed within the baffle passes beneath its lower edge 25 and then immediately rises to the surface of the pulp outside of the baille and subsequently overflows the tank. The overflowing froth is collected in a launder 21 from whence it is distributed to a filter.-

The level of the pulp within the tank is controlled through the medium of a. tails gate 28 whose height is adjustable by the removal or placement of individual weir boards, Figs. 2 and 3.

-The height of the tails gate determines the depth of the froth above the level of the pulp.

The tails gate 28 is supported outside thez'tank and within a chamber 29 which has communicationwith the interior ofthe tank through an opening 30; A tails discharge conduit or chute 3| has connection with chamber 29 on the discharge side of the weir. Passageway 30 is sufficiently below the surface ofthe pulp in tank I!) to prevent the entry of froth and its discharge through the tails discharge conduit.

To the extent the invention has been described,

- the configuration of the upper surface of the tank is immaterial, but there is advantagein making the upper portion of the tank cylindrical about a vertical axis. Such an arrangement enables the employment of a froth skimmer which can travel in a circular path over the area of the pulp protected from agitation. This area surrounds baffle 20 and extends to the edge of the tank. Because of the symmetrical-form of the cell, all portions of the froth. travel the same distance from the baffle to the outer edge of thetank.

The skimmer comprises a plurality of blades 32 which are suspended from a mounting 33 in the form of a ring. This ring is supported on an annular bearing 34 which is carried by the upper ends of brackets 2|, 22, 23 and 24.. The blades are and direct the 'frothto the edge of the tank and into launder-21. Mounting 33 carries a gear ring 35'which is engaged by pinion 36. Pinion 36 is driven from a motor 31 which is supported on brackets such as 38, 39.

The present invention provides a positive circulation of the material not held in thefroth. All of such naterial must go either over the tails gate or to the cone at the bottom of the tank. If it goes over the tails gate it may be caught in succeeding cells and offered to the froth in them. If it settles it will be taken into the pump and again offered to the froth through the discharge header. This allows each particle of ore the maximum opportunity of being placed where it belongs, either in the concentrate or in the tailings. A further advantage of the apparatus lies in its ability to float large particles because the mixture of air and pulp is so thorough and also because of the method of circulation.

In Fig. 5 I have illustrated a modified form of cell. In this cell the baffle "design is such as to,

40 is placed about the baffle sleeve 4| in such a manner as to provide a surface which meets the lower end of the sleeve and is inclined'radially outward in the fashion of a cone. An empty space exists between the sleeve 4| and the deflecting wall 40. The inclination of wall 40 is such as to direct the rising froth radially outward from the baffle as it"rises to the surface of the pulp; The rising direction of flow is such as to cause the frothto flow towards the lip 42 of the tank and discharge into launder 43. For many operations this construction enables the omission of the use of a wiper for directing the flow of froth over the lip. However, if desired, a wiper may be employed and a mounting for the same is illustrated in Fig.

5. This wiper includes a ring carrying a ring gear 45 and aplurality of blades 46. The wiper is driven in a circular path by a motor .41.

The froth flotation apparatus of the present of mi nber,

In'Fig. 6 I have illustrated a system or battery of cells arranged serially for the recovery of-a final concentrate. The feed of pulp to the system is to rougher cell RI and the pulp may be introduced either directly into the tank-of that cell or into the intake side of its pump 52. The tailings from the individual cells are introducedinto the next succeeding cell as, for example, the tailings'from cell C2 are directed to 'the intake side 'of pump 53 of the cell Cl,the tailings from cell Cl are introduced into cell RI through the intake side of pump 52, the tailings from cell RI are introduced into cell R2 through its pump 54,

from the rougher cells RI, I

through conduit 51. The flow of tailings isin one direction, while the flow of concentrates is in the opposite direction. With all 'of the cells at one level, it is indliferent whether the pumps under the several cells are set on one floor level or at diilerent levels, because in either arrangement the static heads on all of the pumps substantially the same. j

What is claimed is:

1. An ore concentrator of the class described, comprising a tank for containingore pulp and providing a settling space having a discharge outlet; means for recirculating pulp under pres? sure from and to said tank, said means comprising a pump having its suction side connected to said discharge outlet, spray discharge nozzles directing their discharge against the pulp contained in'said tank, said spray nozzles being elevated sufllcientlyabove the level of the pulp to discharge through the open air and-aerate the pulp after it leaves said no'zzles,'and means connecting the discharge side of said pump with said nozzles and providing with said pump a closed conduit from the settling space of said tank to the discharge orifices of said nozzleswhereby setremain tling pulp is circulated and forcibly discharged from said nozzles; a b'aiile in said tank and surrounding the area of impact of the discharge from said nozzles into the pulp in said tank, said bame being clear ofsaid nozzles and extending to such a height above the level of pulp in said tank as to prevent froth from overflowing its upper edge and extending suiliciently below-the level ofpulp-to confine the area of agitation produced by dischar e from said nomles and to protect from agitation-the body of pulp and rising froth outside of the locus of impact of the discharge of said nozzles into the pulp in said tank";

a tailsgate having an opening thereto from the side of said tank and providing a weir whereby the level of the pulp in said tank is located intermediate the upper and lower ends of said baiile, and a launder for receiving froth from the tank after it has risen through the pulp outside of said baiile.

2. An ore concentrator of theclass descri comprising a tank for containing ore pulp and providing a settling space centrally thereof with a discharge outlet at its lower portion; means for circulating pulp from said settling and for aerating the circulated pulp y projecting it through the airand into the pulp in said tank, said means including a pump having its suction side connected to said discharge outlet. spray discharge nozzles mounted centrally of said tank and above the pulp level of said tank and direct-- ing their discharge'through the air and against the pulp contained in said tank, and means --connecting the discharge side of said pulp with said nozzles and providing a closed conduit from said pump to the discharge orifices of said nozzles whereby a relatively high emission velocity is attainable from said nozzles; .a tubular baiile in said tank and surrounding the area of impact of the discharge from said nozzles into the pulp in said-tank. said baifle beinl clear of said nozzles I and extending to such a height'above the level of pulp in said tank asto prevent froth from overflowing the upper edge of the baflle and extending suiilciently below the level of pulpto coniinetheareaof agitation'ofsaidpulpfromthe' body of pulp surrounding the baiile and to permit the passage of froth beneath its lower edge outwardly of said baille:-a tailsgate having an opening thereto from the side of said tank, and a launder for receiving froth from the tank after it has risen through the pulp surrounding said baiiie, said launder being substantially concentric with said baiile for providing uniform distances for all particles of froth to travel from said baille to the launder. v

3. An oreconcentrator of the class described, comprising a tank for containing ore pulp, said tank having downwardly converging'side walls and providing a settling space with a discharge outlet at its lower portion; means connected with said outlet whereby pulp is recirculated and aerated, said means including a pump having its suction side connected to said discharge outlet,

spray discharge nozzles mounted centrally of said a tank and above'the pulp .level of said tank and directing their discharge through the air and against the pulp contained in said tank,"and conduit means connecting the discharge side of said pump with said nozzles; a tubular bailie located centrally in said tank and surrounding the area of impact of the discharge from said nozzles into the pulp in said tank, said baiiie being clear of said nozzles and extending sumciently high above the level of pulp insaid tank to prevent froth from overflowing its upper edge and extending suillciently below the level of pulp to segregate a relatively quiet body of pulp out-.

side of said baifle to which froth passes from under the lower edge of said baiile and rises therethrough, a tailsgate having an opening theretofrom the side of said tank and providing a weir whereby the level of the pulp in said tank is located intermediate the upper and lower ends of said baiile; a launder surrounding the upper edge of said tank for receiving froth after it has risen through the pulp outside of said tubular battle, and a tapering wall adjacent the exterior of said baille flaring upwardly and outwardly for directing the froth rising in the relatively quiet body of pulp outside of said baiile towards the side wall of said tank and launder.

DONALD S. PHELPS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED .s'rs'ms rA'mN'rs

Images