US1401598A - Flotation apparatus - Google Patents

Description

RUDOLF GAHL, 0F M, ZONA., ASSIGNQR, `BY MESNE ASSIGNMENTS, T0 PNEU.. MATIC PROCESS FLOTATION COMPANY, 0F NEW YORK, 1\ T. Y., A. CORPORATION 0F :DELAWARE Application :filed January 29,' 1918. Serial $510.A 214,318.

`To all wlwm t may concern:

Be it known that I, RUDOLF GAHL, a citizen of the United States, residing at Miami, 1n the county of Gila and State of Arizona,

have invented certain new and useful Im provements in Flotation Apparatus, of which the following is a specification.

My, invention relates' to' an improved apparatus for use in the concentration of ores by what is now known in the art 'as flotation? or the process by which the valuable minerals in a mass of finely ground ore are caused to iioat on a liquid with which the I have found that it 1s important to main tain a certain percentage of granular material, z'. e. sands, n' the pulp; and the present application relates to means for so conducting the process as to best make use of this percentage of coarse material by modifying the consistency of a pulp-body of the kind above referredto in the course of the operation.

In forated bottoms through which the mass of pulp iows, the mixin of the coarse and ine pulp particles resulting from. the injectlon of air through the porous bottom is not complete, and there is a certain amount of straticationz'. e.' the lower layers will contain a greater percentage of' the larger grams,

the ratio of liquid to solid matter beingtherefore lower and the pulp relatively denser in this layer.

There are now in use pneumatic flotation machines, which utilize baffles having their lower edges spaced from the bottom of the machine. In this manner eddy-currents are formed near the bottom which have the effect of'moving the 'sand particles relatively fast, and are for thisreasonv perhaps re-l s onsible for the shortcomings of such mac ines in that a low recovery of the coarser particles is thus effected. Such eddy-currents were, however, thought .to be essential for the smooth operation of such machines rnorarron Arr flotation tanks provided with-per.

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Specification of Lettera Patent. Pmtgmmg @De 2%', gg.

whenever th bottom was horizontal only a gentle slope.

. I find now that eddycurrents are not necessary and'can be dispensed with by pro# vldlng baffles which reach clear down to the bottom l of the flotation machine, and are provlded with openings or perforations in such'a mannerthat an even stream of pulp results. y

.A further advantage of this mode of operation 1s that the granular material is subjected to flotation treatment in the form of a thlcker pulp, while the slimy material is or had treated as amore dilute pulp, both forms of the material bein therefore subjected to the action of the a1r bubbles in tlemanner best adapted centration.

' The invention will be more clearly under-'- Fig. 3, shows a cross-section of a modified.'

form; and

vfor more complete flotation con- I Fig. 4 shows in elevation one of the'partitions used in Fig. 3. l nReferring vto Fig. 1, the may be of any of the well-known construcporous bbttom.

tionsin which air under pressure is forced through a perforated diaphragm .2,'into the mass of ore pulp.l I prefer to .use the form of bottom described and illustrated on pp. 611 and 612i of vol. 55 ofthe Transactions of the American Institute of Mening En'ginears for 1916, which bricy stated comg prises removable air-chambers having rous to s 2, air under pressure' being introduced into the chambers through pipes 50, Fig. 1. Arranged atsuitable intervals, and extending' upward from the porous d iaphragms are baffles 3, 3. 4 1s the front-line over which the lfroth Hows in the well-known manner. v

In case it is desired to subdivide the tankinto compartments, perforated partitions may be used. Thus at 6, Fig. 2, is shown a 'partition having a slot 7 extending subnext, the bottom of the slot being a con' siderable distance, e. g. from 12 to 2 inches tion.

above the porous diaphragm.

At 8, is shown a partition having several slots'containing guiding lips 9. At 10 and 11 are shown other forms of lips, all these forms of lips being preferably so shaped as to downwardly direct the flow of pulp from one compartment to the next. ln Fig. 2, the direction of flow of the ore pulp through the tank is indicated by the arrow 12.

In the form of apparatus shown in Figs. 3 and 4, the partition 30 is shown as provided with-a series of perforations 31. lin operation, the pulp, prepared for flotation by admixture of a suitable frothing agent, is delivered into the tank at one end through. the conduit 15, flows over the-porous bottom, and is delivered at the other end preferably over a weir 16, to the delivery conduit 17. An upwardly directedv air jet 27 may beused at this point to keep the passage 19 open and to assist the dow of pulp through the tank.

As above pointed out, the air-bubbles passing up through the perforated diaphragm 2 do not e'ect a `complete mixing of then co'arserand iner particles of the pulp, tllegcoarser particles tending to formian underlying stratum of relatively thicker pulp, which i's rst subjected to the flotation reac- The forward movement of this underlying stratum is delayed by the bames 3, 3, (Fig. 1) or by the perforated partitions, 1ocated. at suitable distances apart, so that ample time for their eective flotation isv given. The thinner or more dilute overlying portion is also subjected to the action of the rising air bubbles and isthus also treated in the best condition, since, as is wellknown, slimy pulp is best treated when largely diluted.

\ The bottom of the tank may be horizontal or inclined. Even with a horizontal bottom,

there will be no trouble with sand blanketing the porous diaphragm, as long as this diaphragm is kept in good working order. ln the arran ements shown. in Figs. 2, 3 and 4, the partltions prevent the froth from moving from one compartment to the next, while the openings'therethrough vprovide a free passage of the tailings from each compartment to'. the next one. rlhe number and arrangement of the openings is such as to cause the pulp to flow in an even stream. rThe result of this construction is that in long machines having a more or less inclined bottom, the level of the pulp in each successive compartment will be lower than that above it, so that the depth of pulp in each compartment will be essentially the same .throughout the whole length of the machine.

The various' forms' of guiding lips shown have the common feature that they :torce the Montse pulp moving from one compartment to the nextto take a somewhat downward course through which it is not likely that mineral particles made buoyant by attached airbubbles will follow. Such buoyant mineral particles will, on the contrary, be unobstructed in their natural upward course.

As an example of practical operation, ll will refer to a test made in a concentrating plant, the How-sheet of which is briefly as follows 'llhe ore after having been ground to a suitable fineness by a combination of rockcrushers and ball-mills and having been oiled in the ball-mills is passed to flotation machines. 'llhe tailings from the notation machines are separated into a sand and a slime product by a'drag classifier, the sandproduct going to waste after re-treatment .on tables, and the slime products going to waste directly.

The test in question was made with two sections of this plant. rlhe flotation equipment of a section consists of a rougher machine containing in parallel two rows of ten compartments provided with the slotted partitions illustrated at 6 in `Fig. 2. The

rougher concentrate is re-treated on a cleanerv machine consisting of two rows of siX compartments each of somewhat smaller dimensions. While the cleaner concentrate represents a finished product, the cleaner tails arev returned to the rougher machine.

Several thousand tons of ore were treated in the manner described, and the following figures represent the principal results of ,a twenty-four hour run:

Tonnage treated 1516.4 tous.

Fineness otgrinding 4.3% on '48 mesh.

Feed assay '1.00 sulfd copper.

Slime failing .11 on 48 mesh.

Sand tailing .14

Flotation concentrate 32.30

Table concentrate 15.78

ll claim:

1. An apparatus for ore pulp concentration comprisin a tank having a porous bottom impermeale to the downward passage therethrough of ore pulp, means for forcing gas therethrough, partitions subdividing the tank into compartments, said partitions eX- -tending to and being imperforate in imforcing gas therethrough, and partitions subdividing the tank into compartments, said partitions extending, to and being imperforate in immediate proximity to the bottom of the tank and provided withv openings above said bottom, said openings having lips arranged to guide the pulp downwardly in linto compartments, said partitions extending its passage through said openings. to the bottom of the cell and provided with 3. A long .straight-line flotation cell havopenings spaced and distributed above said 1t ing a porous bottom impermeable to the bottom. 5 downward passage therethrough of ore pulp, In testimony whereof, I afiix my signature.

means for forcing gas through said porous v bottom, and partitions subdividing the cell y RUDOLF GAHL.

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