US 2652924 A
Description (OCR text may contain errors)
Sept. 22, 1953 R WUNSC APPARATUS FOR THE CONCENTRATING OF MINERALS BY MEANS OF FROTH FLOTATION Filed July 20, 1949 IVNTOR.
Patented Sept. 22, 1953 APPARATUS FOR THE CONCENTRATING; F. MINERALS. nY MEANS OF FRoTn morp Rudolf Wunsch, Milan, Italy Application J uly20, 1949, Serial-No, 105,8,i8v
In ItalyvJuly 21, 19%18 8' Claims. (01. 209-169) It is the. object of. the present invention to Provide. such improvements. in oi' relating to par tus a car ou re c e n r t on b thefroth flotation process, as may result in ape paratus of anew type or be'applied with an.- paratus qf other types already existing or of new types that might be developed and proposed. Flotation machines operating by mechanical agitation arel nown wherein aeration of the pulp is proyidedby a rotating impeller in an agitatin compartment divided by a vertical. wall from the rot emana in m ar t a wall having in its upper portion a port through which the pulp enters into a frothing chamber having a hopper shapa the so-called spitzlrasten. At the bottom of this spitzkasten there is a pipe. for returning the pulp to the rotor on impeller in the. a in com a tmen It was found that these impellers lprovide maximum, aeration of the pulp if they carry radial blades revolvingunder. and close to a flange; however, this type of impeller requires much power for maintaining sufficient circulation of the pulp between agitating compartment and spitzlzasten. On the other hand, if the impeller is provided with curved blades likethose of. a centrifugal pump, power requirements diminish, but aeration also diminishes considerably. The attempt was made to eliminate. this moonvenience by providing a double rotor equipped with both curved blades and radial blades, the pulp entering into the double rotor from. top and passing partly through the radial blades and partly" through the curved blades, so that suflicient aeration and circulation is attained.
The present invention provides for two separate rotors in the agitating compartment; a lower rotor at the bottom of the agitating compartment, "shaped like the rotor of a centrifugal pump; and upperrotorcarrying radial blades. The connection b'etweenthese two rotors is such that the lower'rotor forces the whole pulp, both the pulp fed from the preceding. cell and the pulp circulating inside the compartments to pass through the upper rotor, in order to attain perfeet aeration. It is therefore a specific object of thepresent invention to provide a froth flotat apparatus in whieh the agitating comparttans thespitskasten are adjacent one an- 1 the thefagitating compartment is d i d, "to. up er. ge n nd ag t n 'f and a are be a d, a itatii i'e r i it l v ah rizl etina tiiiee ha I A g therein constituting the lower compartments and in which in each compartnient impeller means are arranged, in the lower compartment said means constituting a. pump means including a substantially enclosed rotor and in the upper compartment an impeller constituting a combined aerating andagitating impeller and in which means are providedfor leading the pulp from the spitsliasten to and feeding the same centrallyv of the rotor in the lower omp r m nt an a c s n rw ds he m e n he u er ompa tmen tends up wardly therewithin, terminates atleast adjacent the pulp. ev nd s n, wmml ieet h ith the a t s t ae at thepul he e a.- m i is Such a with q nirelleb e in between theupper compartment and the spits} kasten open and. pulp fed, to the lower coinpart: ment the circulation Of, pulp is efiected and all pulp entering the lower, compartment must pass through the singlet opening inthe horizontal partition into the sphere of action of the inipeller in the. upper compartment and which latter impeller is operative. to draw air into the casing to mix the same with the. pulp.
It is a further and more specific. object to incorporate stationary deflector means in the lower pumping compartment that is positioned subjacent the aperture. in the horiz ontalparti tion and has a surface which in vertical. cross.- section and in combination with the undersurface of the. horizontal partition definesa Venturi type throat so as to accelerate pulp flow through the single opening in the horizontal partitien into the sphere of action of the upper impeller.
It is an additional specific object to incorporatea downwardly open bell mouth flange and to mount the rotor of the pump in position to rotate closely adjacent this flange and provide means for feeding new pulp and means for leading pulp from the spitskasten centrally of this bell mouth flange so that all pulp is fed to the rotor of the pump centrally thereof.
Further and more specific objects will be apparent in the following, detailed description.
An embodiment of the present invention is i1.- lustrated in the accompanying drawings, in which:
Figure 1 is a longitudinal sectional view.- thereof with some parts shown in elevation;
Figure 2 is a top plan view oi; the rotor in the pumping compartment and illustrating the vature ofthe blades thereof; and
Figure 3 is a vertical sectional view through the. stationary deflector and the bell-mouth flange depending therefrom and located pumping compartment and taken at right angles to the illustration thereof in Figure 1 and looking toward the left in Figure 1.
In the arrangement illustrated the fresh pulp flowing from a ball mill or pulp flowing from a preceding cell passes through pipe l and into the diflusor 2 into which circulating pulp returned from the spitzkasten Zll also enters through pipe I8. Under and closely adjacent the bell mouth flange of the diffusor there is arranged the bottom rotor 3 which has curved blades and is driven by the shaft 4. As shown in the drawing this rotor 3 is substantially enclosed since the horizontal disc supporting the same is imperforate and the respective pulp conduits constituting the pipes l and i8 feed the pulp centrally within the bell mouth flange so that the pulp is fed centrally of this rotor. Thus the cooperation of the rotor with the flange in the manner of pulp feed defines a centrifugal pump. The pulp pumped through rotor 3 passes through the central circular port or aperture in the horizontal partition 6. Subjacent this aperture there is arranged the deflector bafile i which has a spherical upper surface and therefore, the whole of the pulp must pass at considerable speed through said central circular port to flow centrally of and beneath the lower part of a double rotor provided with upper and lower radial blades 9 and 8 respectively and driven by the shaft 10. This double rotor revolves within a cylinder l2 having an opening in the wall thereof directed toward the grid l controlling pulp flow into the spitzkasten. Since the pulp raised by the bottom rotor enters the sphere of action of lower part of the double rotor at considerable speed owing to the shape and position of the deflector bafiie 1, this lower part of the rotor, having the radial blades 3, consumes little power because its task is not to accelerate I the pulp but only to aerate it and direct its flow into the spitzkasten.
As a matter of fact, experiments on an industrial scale have evidenced that a considerable reduced speed of operation of the radial-bladed rotor is possible while maintaining active aeration of the pulp. The upper part of the double rotor also carries radial blades 9 turning under a flange formed by the conical vessel I i and this part serves to aerate the overflow, which is adjustable at will by adjusting the position of the gate l3 through which the pulp is discharged to th subsequent cell. The level of the pulp in the spitzkasten 29 can be adjusted at will by raising or lowering the grid 15 by means of the hand wheel It. The grid I? in the spitzkasten serves to calm down the pulp impelled by the double rotor. In order to ensure rapid progress of the froth toward the discharge scraper 22, a movable apron 2| is so arranged as not to restrict the frothing surface.
It is therefore clear that this invention provides a froth flotation apparatus comprising tank means which includes a vertical partition and a horizontal partition 6 extending from on side of and intermediate the ends of the vertical partition. These two partitions divide the tank means into three compartments comprising an aerating and agitating compartment above the horizontal partition, a pumping and agitating compartment beneath this horizontal partition and a spitzkasten on the opposite side of the vertical partition. The horizontal partition is provided with a single central opening therein affording communication between the pumping and agitating compartment and the aerating and agitating compartment. The vertical partition has an opening therein above the horizontal partition which is controllable and which provides a communication between the upper aerating and agitating compartment and the spitskasten. A pump means is provided in the pumping compartment and includes a substantially enclosed rotor and in addition the conduits l and I8 are provided which feed new pulp and pulp contained in the spitskasten centrally of the bell mouth flange beneath which the rotor 3 rot/ates so that all pulp is introduced centrally of this rotor so that when the same is operating it draws the pulp into the center thereof to agitate the same and force the pulp to flow through the single central opening in the horizontal partition. When the pump is in operation therefore, a pulp circuit is afforded between the three compartments. Within the upper aerating and agitating compartment there is provided a cylindrical casing of greater diameter than and surrounding the single opening in the horizontal partition. This casing extends upwardly from th horizontal partition and terminates at least adjacent the pulp level that is maintained in the upper aerating and agitating compartment in accordance with the adjustment of the gate I3. The casing is open to the air, that is to aerate the pulp and in the position of adjustment shown this casing terminates slightly beneath the pulp level in the upper compartment so that pulp cascades into the casing in a thin veil. This casing l2 is provided with an opening in the wall thereof that faces the opening providing communication with the spitskasten. An aerating and agitating impeller is mounted within the casing for rotation on a vertical axis. This impeller includes a horizontal disc having upper and lower sets of radial blades with the lower radial blades disposed closely adjacent the horizontal partition. The
' operation of this impeller sets up a suction action as regards the casing so as to suck air into the casing and beat the same into the pulp. The lower .blades are impinged upon by the pulp forced by the pump out of the lower compartment which action enables the operation of the upper impeller at reduced power and which upper impeller will accelerate the agitation of pulp initially agitated in the pumping compartment and thoroughly mix air with all the pulp that flows through the central aperture in the horizontal partition.
As shown in the drawings the deflector means I is positioned coaxially of and subjacent the single opening in the horizontal partition. This deflector constitutes a body having a spherical upper surface so as to provide a channel of decreasing or reducing size or width between the outer limits of the deflector and the opening. In other words any vertical cross-section taken through deflector I and the horizontal partition defines a space between the partition and the upper surface of the deflector that narrows in width toward the central opening to provide a Venturi type throat to accelerate pulp flow through said single opening, as shown in Figures 1 and 3.
The arrangement therefore provides froth flotation apparatus in which all new pulp must be subjected to the action of the pumping and agitating rotor and the upper aerating and agitating impeller and additionally any pulp that has passed through these two mechanisms and flow into the spitskasten positively recirculated at least once through both of these impeller means before it n ove f ow thr gh the gate I3 to the next cell. w
As-isclearfrom the showing-inFigures-l' and 3', the'means for leading pulp from the spitskasten to and feeding the same centrally of the rotor includes the conduit 18' iii-communication with the spitskasten beneath the horizontabpartition and extending within the pumping compartment. The stationary deflector body 7 mounted' beneath the single central opening in the horizontal partition has an aperture therethroughin communication with the conduit Hi. This aperture-terminates in a downwardly directed opening above the rotor. The raw pulp inlet conduit i also extends within the pumping compartment. The deflector body has another aperture therethrough that terminates in a downwardly directed opening above th rotor. This aperture: communh cates with conduit I. An annular depend gbell" mouth flange is embodied with the body for partly delimiting and surrounding both the-said openings. The rotor'rotates closely adjacent this flange so that'the pulp feedscentrallythereof from'both said openings.
The two rotors may be driven by separate shafts or by a single shaft. Ofcourse; the inven tion may be embodied'in a manner different from that illustrated, without departing from. the scope'ofthe invention as defined'in the appended claims.
Having now particularly described-andascermined the nature of my said invention and: in what manner. the same is to be performed; Ideclare that'what I claim is:
1. In a froth flotationapparatus means defining an agitation compartment and a spitslrasten both adapted to contain pulp, a vertical :wallseparating the same, ahorizcntal partition dividing the agitating compartment into an upper aerat ing and agitating compartment and. a lower pumping and agitating compartmenheaid horizontal partition having only a single opening therein, said wall having an opening therethrough above the horizontal partition andproviding" communication between: said upper compartment and said spitskasten, pump means within the pumping compartment including a substantially enclosed. rotor, means for leading pulp from the spitslrasten to and feeding the same centrally oi the rotor, a cylindrical asing surrounding said opening in the horizontal partition and extending upwardly within said upper compartment and terminating at least adjacent the pulp level therein, said casing being in communication with the air that is to aerate the pulp and having an opening therein adiacent the horizontal partition, a combined aerating and agitating impeller within the casing and rotatable therein. at the level of said last mentioned opening, and operative to draw into the casing to mix same at least with the pulp forced through said single opening by said pump rotor.
2. Froth flotation apparatus comprising tank means including a vertical partition and a horizontal partition extending from one side of and intermediate the ends of the vertical partition, said two partitions dividing the tank means into three compartments comprising an aerating and agitating compartment above the horizontal partition, a pumping and agitating compartment heneath said horizontal partition, and a spitskasten on the opposite side of the vertical partition, said horizontal partition having a single central opening therein providing communication between the pumping and agitating compartment and the aerating and agitating compartment, said verthe pumping. and agitating compartment and; the
tical' partition-- having; an opening therein: above the horizontal partition to provid communication between the aerating andagitating compartment and thespitskasten, apump means in the pumping compartment includinga substantially enclosedrotor, means for feeding pulp into the pumping compartment including means for introducing pulp to said rotor centrally thereof, means for" leading pulp from said spitskasten to the meansior introducing-pulp centrally of the rotor so that operation of therotor draws pulp into thecenterthereof'toagitate the sameand 'lorce pulp through the single central opening in the'horizont-al partition from whence it passes through saidaerating and agitating compartment and lows into-said spitskasten for-recirculation and frothseparation, a cylindrical casing surrounding the single central opening in the horizontal partition, extending upwardly thereof and terminating at least adjacent thepulplevel in theaerating and agitating compartment, said casing being open to the air, and'said casing further having-an opening above the horizontal partition and directed toward the opening providing communication with the spitskasten, an
tion, a pumping and agitating compartment beneath said horizontal partition, andaspitskasten on the opposideside of the vertical partition, said horizontal partition-having a single central opening therein providing. communication between aerating. and agitating compartment, said verticalpartition having an opening therein above the horizontal partition to providecommunication:betweenthe aerating; and agitating com artment and the spitskasten, a pumpmeansin-the pumping: compartment including a substantially enclosed rotor; means for feeding pulp into the pumping compartment, including: means for introducing pulp to; said rotor centrally thereof, means for leading; pulp from said spitsliasten to the means for introduc ng pu pcentrally Of the rotor so that operation of the rotor draws pulp into the center thereof to agitate the same and force pulp through the single central opening in the horizontal partition from whence it passes through said aerating and agitating compartment and flows into said spitskasten for recirculation and froth separation, a cylindrical casing surrounding the single central opening in the horizontal partition extending upwardly thereof and terminating at least adjacent the pulp level in the areating and agitating compartment, said casing being open to the air, and said casing further having an opening above the horizontal partition and directed toward the opening providing communication with the spitskasten, an aerating and agitating impeller mounted within said casing, and including a horizontal disc having upper and lower sets of radial blades, and
with the lower radial blades disposed closely adjacent the horizontal partition, said agitating impeller drawing air into the casing to mix with the pulp and further accelerating the agitation of the pulp initially agitated in the pumping compartment so as to thoroughly mix air with all pulp flowing through the single central opening in the horizontal partition.
4. Froth flotation apparatus as defined in and by claim 3 and including a stationary deflector positioned coaxially of and subjacent the single central opening in the horizontal partition, said deflector constituting a body having an upper surface defining in vertical cross-section and in cooperation with horizontal partition a conduit of reducing size with the narrowest size being adjacent the said single central opening so as to provide a Venturi type throat through which all pulp contained in the pumping and agitating compartment must pass and said throat accelerating pulp flow to the upper aerating and agitating compartment.
5. Froth flotation apparatus as defined in and by claim 3 in which the cylindrical casing surrounding the single central opening in the horithe top to the bottom of the casing and terminating in spaced relation to the upper surface of ,said horizontal partition and defining a central .axial opening in the cylindrical casing, said casing terminating at least slightly beneath the pulp level in the aerating and agitating compartments so that pulp cascades over the same and through the said central axial opening, horizontally disposed flange portions extending between the lower terminal end of the conical surface and the inner surface of said casing, and the upper radial blades of said aerating and agitating impeller being rotatable immediately subjacent the said horizontal flange portions so that when said agitating and aerating impeller is rotating air is sucked through the casing together with the pulp cascading thereinto and which pulp and air are thoroughly mixed with the pulp flowing from the lower pumping and agitating compartment through the said single opening in the horizontal partition.
6. A froth flotation apparatus as defined in and by claim 1 in which the means for leading pulp from the spitskasten to and feeding the same centrally of the rotor includes a conduit in communication with the spitskasten beneath said horizontal partition and extending within the pumping-compartment, a stationary deflector body mounted within the pumping compartment subjacent the single central opening and having an aperture therethrough with which said conduit communicates, said aperture terminating in a downwardly directed opening, a depending annular bell mouth flange embodied with said body and surrounding said last mentioned opening, and said pump rotor being rotatable closely subjacent said bell-mouth flange and receiving pulp centrally thereof from said downwardly directed opening.
7. A froth flotation apparatus as defined in and by claim 6, and further including a raw pulp inlet conduit extending within said pumping compartment and terminating therewithin, said stationary body having another aperture therethrough terminating in a downwardly directed opening, said last mentioned aperture being in communication with said raw pulp inlet conduit at one end and through said downwardly directed opening with said bell-mouth flange at the other.
8. A froth flotation apparatus as defined in and by claim 7, and in which said stationary body is mounted coaxially beneath said single opening in the horizontal partition and has a spherical upper surface, the axis of which is coaxial with said opening so that the said upper surface in cooperation with the undersurface of said horizontal partition defines a pulp conduit of reducing width with the narrowest width adjacent said single opening in the horizontal partition thereby accelerating pulp flow into and through said single opening in the horizontal partition.
References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,277,750 Pearce Sept. 3, 1918 1,457,077 Janney May 29, 1923 1,463,405 Ruth July 31, 1923 2,148,446 Drake Feb. 28, 1939 2,189,779 Daman Feb. 13, 1940 2,240,671 Shorlino May 6, 1941 2,246,560 Weinig June 24, 1941 2,410,429 Daman Nov. 5, 1946 2,433,592 Booth Dec. 30, 1947 OTHER REFERENCES Taggart: Handbook of Ore Dressing, John Wiley and Sons, Inc., New York 1927, pages 802, 803.
Taggart: Handbook of Mineral Dressing, John Wiley and Sons, Inc., New York 1945. Section 12, pages 12-77 and 12-78.