US1557369A - Means for skimming off froth - Google Patents

Description

Get 13, 1925. 1,557,369

J. W KLEINBENTINK MEANS FOR SKIMMING OFF FROTH Filed Nov. 6, 1923 suitable Patented Get 13, 1925..

- STA JAN WILLEM KLEINBENTINK, 0F HOE-NSBROEK, LIMBURG, NETHERLANDS, ASSIGNOR T0 NAAMLOOZE VENNOOTSCHAP VEREENIGDE KOLE'NMAATSGHAPPI-l' EN 'IER VOO'RTZETTING DEB STEENKOLENZAKEN, GEDREVEN' DOOR DE N. V. FURNESS KOLENMAATSGHAPPIJ EN HOVMT EN HENNYS HANDELMAATSCHAPPIJ, 0F ROT- TER'DAM, NETHERLANDS, A COMPANY ORGANIZED UNDER THE LAWS OF THE NETHWAND'S.

MEANS FOR SKIMMING OFF FROTH.

Application filed November s, 1923. Serial at. 673,208.

To all whomt't may concern:

Be it known that 1, JAN WILLEM KLEIN- BENTINK, a, subject of the Queen of the Netherlands, residing at Hoensbroek, Limburg, Netherlands, have invented ccertain new anduseful Improvements in Means for Skimming OER Froth, of which the following is a specification.

This invention relates to improved means for skimming off froth, such means being applicable for instance in apparatus for refining coal slimes in accordance with the froth flotation process. With known means of this character it is not possible to skim the aqueous blanket 0d the surface of the liquid from which the froth has developed without breaking up part of the bubbles, especially when the bubble formation is very fragile and has bad lasting qualities.

The present invention comprises means for skimming off froth overlyingthe surface of liquid in a vat, consisting of stationary and rotary skimming elements, either the stationary or rotary elements being rigid while the others are yieldable so as to enable themto pass over each other.

The annexed drawing illustrates a novel froth skimming apparatus made in accordance with the present invention and which is capable of removing the aqueous blanket of froth without deteriorating it.

Figure 1 is a plan view of a circular froth containing vat provided with skimming apparatus in accordance with the invention, Figure 2 being a vertical sectional View thereof.

Figure 3 shows the elevational view of a detail, viz. a stationary yielding wall adapted for co-operation with rotary, rigid skimming blades, whereas Figures shows the cross-sectional view of said yielding wall.

In these drawings a conical mixing vat a, in which the froth form is produced in a manner, is ii communication through openings 1) near its bottom with a surrounding annular froth containing vat 0 in the form of a downwardly pointing cone, into which the. froth developed in vat a is adapted to be transferred and in which the bubbles rise to the surface of the liquid.- Two rigid, spirally curved-skimming blades e are mounted for slow rotary movement about a vertical spindle all in the direction of the arrow; during this rotation the blades 6, the lower edges of which extend below the surface of the liquid, force the froth outwards. Arranged between the wall of the mixing vat a and that of the froth containing vat 0 is a plurality of radial, stationary skimming elements or walls 7', extending with their upper edges above the froth blanket and with their lower edges some distance below the surface of the liquid. These stationary walls are adapted .to yield in the direction of rotation of the skimming blades 6, so that the latter can pass over them. As shown in the drawing, each wall 7 is composed of a plurality of narrow, metal strips h arranged side by side and each weighted as at g, said strips being pendulously suspended from a shaft 5 a slight distance above their centres of gravit y 1 During rotation of a blade 6 the space between this blade and the wall f next to it in the direction of rotation gradually decreases. The froth in this space is retained by the upright wall f, so that the blade 6 acts to skim the froth 0d over the upper edge of the froth containing vat. As soon as that part of the blade e which is adjacent tothe mixing vat a engages the inner strip h of wall f said strip yields so as to allow the blade e to pass, after which the wall slowly resumes its upright position. During this slow oscillation of the strip h the liquid is not appreciably agitated so that the froth blanket is not damaged. The other strips h of wall f consecutively perform the same movements.

The manner-in which blades e are driven is of subordinate importance as far asthe (I present invention is concerned. In the exright position; in this case the strips need not extend into the liquid through any appreciable distance so that they hardly agitate the liquid whenoscillating. Furthermore, the yielding walls f could be rotatable about axis d when the rigid skimming blades e would have to be stationary.

Equally good results would be obtained by makingthe skimming blades. e yielding and the retaining walls f rigid. These and other modifications fall within the spirit and scope of the invention as expressed in the accompanying claims when broadly construed.

The novel apparatusmade in accordance with the present invention, has moreover, the advantage of being cheap to-manufa'cture and reliable in operation. 7

Having now particularly described and ascertained the nature of my said invention to contain a liquid with surface characteristics induced by froth flotation, of skimming means to remove the froth, including a rotary skimming element and a relatively fixed skimming element, said elements being adapted for actual and displaceable contact in operation, said rotary element having a convex pressure :face and the fixed element being directly radial of the vat.

3. The combination with a vat adapted to contain a liquid-with surface characteristics induced by froth flotation, of 'skimming means to remove the froth, including a radial element made up of a series of indetu pendently movable sections, and a rotating element having a convex pressure face operating in part in a path including the radial element, said rotating element displacingthe sections of the radial element in succession. w v

4. The combination with a vat adapted to contain a liquid with surface characteristics induced. by froth flotation, -of skimming means to remove the froth, including a radial element gnade up of a series of independently movable sections, a rotating element having a convex pressure face operating in part in a path including the radial element, said rotating element displacing the sections of the radial element in succession, and means for returning said sections of the radial element to normal position.

5. Thecombination with a vat adapted to contain a liquid with surface characteristics induced by froth flotation, of skimming means to remove the froth, including an ele ment extending radially tothe edge of the vat-and made up of a series of independently movable sections, a rotating element having a convex pressure face operating in part in a path including the radial element, said rotating element displacing the sections of the radial element in succession,-and means resisted by the body of liquid in the vat to slowly return said sections to-normal position, whereby to avoid undue agitation of the froth area.

6. A conical mixing vat adapted to contain aliquid with surface characteristics induced by froth flotation, aplurality of rela-. tively fixed walls extendin radially and" throughout the full radial listance of the v'at, and a series of movable skimming eleinents, each having a convex pressure face and operating throughout a linear distance in the vat materially greater than the radial distance, and means for operating said movable elements the relatively fixed walls being displaceable through contact with the movable elements.

In testimony whereof I aifix my signa re. 4 v

JAN'IWILLEM KLEINBENTINK.

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