US2983382A - Separating tables - Google Patents

Description

`SEPARATING TABLES Inn D. Russell, Sandringham, Johannesburg, Union oliY Soutl'lxAfxica, assgnor to The Denver Machinery Company (Proprietary) Limited, Johannesburg, Transvaal, Union of South Africa Fired ocr; 29, 195s, ser. Ne. 110,559 :6 claims. (ci. 2091-458) This invention relates to the separation of substances into two fractions, one of which is heavier than the other, by making use inthe main of a dierence or differences in specific gravities. Y

In` particular it relates to the'separation of the mineral content from the waste contentof ores whichV have been reduced to duid-solidmixtures, in ,which the degree of nenss-'of the solids and the proportion by weight are Suited to the particular ore involved.

Knownseparating tables employ the principle that, in 1a metallurgical fluid-solids mixture moving over a surface,r the hea'v) fraction o'r'fractions tend -to settle on the surface while the lighter fraction orefractions VYremain in the top'lay'er and are carried over the surface.A An example of a vseparating table is that employed in the gold mining industry, comprising a table of corduroy, over which the gold-bearing fluid-solids mixture .is run transversely Y toy The gold settles against Y the corrugatons of the material. the nfes and is removed by known methods. v ...llt is ,an object of the'present invention to provide a separating table that permits afcontinuous separation of mineral ory minerals at a greater rate than was previously attainable and with a greater c iciency.

- LAccording tothe invention a separating table for metal#v lurgical duid-solids mixtures or the like comprises two or more surfaces ribbed longitudinally to form channels, theA walls of which are the ribs, the ends of adjacent surfacesV being `separated by transverse gaps, adjustable blade means associated with and overhangi'ng the gaps.4 and 2 The ends of the walls of the channels or the ends o f the extensions of such walls are hereinafter referred to as the ends of the ribs. Thus, the heavier fraction or fractions pass through the adjustable openings formed by the bases of the channels, the ends of the ribs and the leading edge of the blade. The lighter fraction or fractions flow overV Y the blade means to the next surface Where further gravitation of the fraction or fractions. will take place,

The method of mounting the blade must be such that it can be moved in planes normal and planes parallelv to the surface'of the table,vand can also be tilted, since yfor proper operation ofthe table the `leading edge of thev blade must alwaysbe in contact with the ends ofthe ribs.

In a modiiedform of the invention the blade is mounted at or near the leading edge of a surface with respect to the directionsv o'fjow o f the Huid-solids mixture in aY similar way tothe preferred form, and is in 'contact with the bottom of those parts of the ribs which overhang the trailing edge ofthe preceding surface, and overhangs the l gap to a variable partial extent., As in the case of the preferred form, the heavier fraction or fractions pass through the adjustable openings. which in Ithe modified form are thus formed by the leading edge of the' blade, the bases of the channels at theV trailing edge ofthepreceding .surface and pantsl of the ribs. The adjustable openings may also be formed by adjusting the blade back in the direction of iiow of the fluid-solids mixture,v and, then ladjusting it to come in contact with the endsof the.` ribs. The method of mounting thejblade must be such that .it can be moved` in planes normal and planes parallelto the surface of thetable, and can 'also be tilted.

In the majority of cases turbulence is undesirable for a successful separation, vand the underside 'of vtheblade is designed in such a manner to maintain :as stream lined a lilow as possible after the heavy fraction or fracf tions have `,passed through the adjustable openings. The, trailing .edge of thepreceding surface and the ends of the ribs may also be designed ,to maintain as streamlined a. flow as possible. .iln the three cases the designsV ccmtern-A plated are curvatures suflicient to create lal streamlined ,f oW. The widthjof the ribs may also be. designed in such a manneras to obviate turbulence as muchas possible.V

adapted to Contact with its leading edge the ribs Vnear the? trailing edge of the surface with respect to the direction ofthe-dow of the duid-solids mixture tofpresent-anse'ries of adjustable openings to the ow of themixture.

vthe`preferred form of the invention, theA separat-ing table may comprise acascade of ribbed surfaces along thelength of the table.I `V f Y n The functions of the channels are at 'least threefold. Firstly the heavy fraction or fractions are assisted lthereby to gravitate towards the bases ofthe channels and s'to separate from the lighterfractions.l Secondly, they pre# vent the fluid-solids mixture, when fedv under. proper In the operation ofv timetable,k a, fluid-solids mixture containing the mineral-or minerals. is fed OnftO Oneend: substantially evenly, the table being approximately level across its width and the longitudinal slope and degree of tion or fractions cascading being determined'by `exlgeriment for ydifferent Y ores'. Y t Y v The heavyfraction or fractions having gravitated` tof.K wards the ybases of the channels pass through the adjustable openings to a collectingtraywhile thelighter frac-.

`ribbed surface.' l

conditions, from flowing `to oneor otheraside `after entering the .channels,should the table not beperfectly level across its width. Thirdly, the'channelsassisttodis` tribute the'ow satisfactorily over the full width .of the table, -and'thereby ensure as far as possible even gravitation of the heavy fraction: orfractions.' means is preferably mounted at ornearrthe leading edge of aV surface with respectfto `the direction of flow/ofthe The blade f, i. 'Ihetablemayeither be stationary/primary lac-' "vibratedv l during the operation. .tr *Y According ,to` the 'substance' or; substancesto Y be sepa-` rated,"l it maybe necessary to include one or ,moreyi'otaf tion reagents,` wetting agents orrother compounds',toas:Vv

sist' in the separation'oftlie heavyv fraction or fractions. from, the light fractionor fractions.For example, it` may. be that. d ue totheparticle sizes loff-theheavier fraction or-vfractionsL coupled withfthe surface tensioneffecti fluid-solids mixture and ovcrhangs the `gap to a `variable,

, partial extent. The leadingedge of the 'blade'withr` v spect tothe direction of ow of the duid-solidsy mixture," which edge is hereinafter-referred tojas the'ileading edge v f l ofthe blade, comes into contact with the'ends" ofthey l p s A v l l u Figurel 1s a perspective View of'a separatrngtable; ai".

portion .of thetable ina preferred' forni illustrating as'gap f Y' walls Vof the vchannels near `thetrailing .edge 'offa' pre:-V

ceding ysurface with respect to the direction ofthe iiowfof the'Filuid-solids mixture, fthe latter 'edge fbeing'fhereinaiter.' referred Itoas the trailing ,edge Qf-thexpreceding :Surfaces .Y 7

theheavy,fparticles are caused -to floatlonrthe surface of` thefluidfsolids"mixtureL Thev addition, for example, of a wetting agent mayrei'novefthis diculiy;`

embodiment vof the inventionis described hereunder` y with referencev to theYaccornpanyingv drawings in which Figure 2"'is aV sectional side or longitudinal 'View' off-a1 adjustableplate;A :y :e i

pass,v over the' blade `,tothe following l Figure 3 is a transverse section on the line 3-3 of Figure 1, and

Figure 4 is an enlarged sectional side or longitudinal view of a portion of the table in a modified form illustrating a gap and an adjustable blade.

The table is bound by walls and 11 and comprises a cascade of units, in this case, four, each of which consists of a ilat base 12 upon which are located longitudinal ribs 13. Thus channels are formed by at bases 12 and the ribs 13.

At the end of each unit there is a gap 14, leading to a drawing-off means, in this case represented by a gutter 15, along which the separated portion may flow to collecting means. The bases 12 of the table terminate in a curved portion 16, the curvature of which is designed to minimise turbulence at that point, since any turbulence would cause mixing of the heavyy and lighter fractions. The ribs 13 terminate at the gaps, and the ends of the ribs are at an angle of approximately 135, with a plane parallel'to the surfaces of the units.

' Referring to Figure 2, a blade 17 pivotedat 18 is provided along its length with a number of adjusting screws 19 by which the angle of the blade in relation to the table, its height above the table and its longitudinal position on the table may be varied, and consequently the adjustable openings formed by the bases of the channels, the ends of the ribs 22 and the leading edge of the blade when in contact with the ends of the ribs may be varied for different metallurgical fluid-solids mixtures. Adjustment of the blade in any of the directions of adjustment must be done in such a manner that on completion of the adjustment the leading edge of the blade is in contact with the ends of the ribs 13.

The leading edge of the blade touches the ends of the ribs 13 at points 20 so that the heavy fraction or fractions pass through the adjustable openings, while the lighter fraction or fractions pass over the-top of the blade to the following unit of the table, where the operation is repeated ,until the remainder of the fluid-solids mixture passes over the trailing end of the table with respect to the direction of ilow of the fluid-solids mixture.

-In order further to promote tranquility of ilow in theY neighbourhood o f the blade, the under side of the blade may be curved at 21 along the length of the blade, the radius of curvature being suitably chosen with a view lto minimising turbulence. lFor the same reason the ends of ribs may be rounded, the radius of curvature being suitably chosen with a view to minimising turbulence.

Referring to Figure 4, a blade 17 pivoted at 18 is provided along its length with a number of adjusting screws. 19. The head 23 of a screw 19 is located within a depression 24 of the blade 17.y By tightening `or loosening` the screw. 19, the blade may be adjusted ina plane substantially normal to the table. It will also be rseen that the screw 19 is ablev to slide Within the hole 25 so that theblade 17 is adjustable in a plane parallel to the table. Since the blade 17 is'pivoted `at 18, relieving the tension on bolt 19 by turning the Ynut towards the free end thereof, will cause the ,edgeV 20 to be lowered because of thev disposition of the gutterrelative to the pivot 18. v Obviously, when the nut is tightened on the bolt 19, the edge is moved upwardly. 'In operation the fluid-solids mixture to be concentrated is passedon to the table substantially evenly, the tableY being approximately level across its width, in the direc-" tion shown in Figure 1 by the arrows A. Each blade isv set to a predetermined angle, height andlongitudinalV position according to the composition. of the huid-solids mixture and other factorwhich may be relevant. The table is sloped to a predetermined degree according to the rate 'at-which the huid-solids mixture is to pass over thetable; l

V-For satisfactory working the bases ofthe Vchannels must, be flat and the sides of the ribs should. be inclined slightly. x

4l Y For concentrating certain fluid-solids mixture the bases of the channels should be of the order of one-eighth of an inch wide.

As the fluid-solids mixture flows along the channels, the difference in specific gravity causes the heavy fraction or fractions to graviate towards the bottoms of the channels.

The separating results have been found to be much i more satisfactory where instead of a gap between the leading edge of the blade and the trailing edge of the preceding surface a number of adjustable openings are provided for as described aforegoing.

At the trailing end of a surfacegra certain proportion of the heavy `fraction Yor, fractions is present in the lower sections of the channels. By having' adjustable openings instead of a gap at the end of the preceding surface, and by making provision for maintaining as streamlined a iiow as vpossible through the adjustable openings in the manner indicated aforegoing, such proportion of the heavy fraction or fractions is maintained as muchv as-v possible, thus ensuring that as much of such fraction ori fractions as possible ow through the adjustable openings.

Having collected the different fractions at the pointsv 15 lthe fractions are either re-introduced on to the tablev or another table or further treated in some-other way.

In constructing a table according to the invention, care-l should be taken to ensure that the ribs are as as possible and at the required distance apart having regard to the ore mixture to be treated. 'Ihe sides of the ribs should be sloped, the angle again depending on the mixture of ores to be separated since the sides of the ribs assist materially in the separation and prevent blocking of the openings by large particles. Particles which have the same or greater diameter as the width of the channels, and of the openings, will tend to ride above the blade. i

I claim:

1. A separating table for metallurgical fluid-solids'mixtures comprising at least two surfaces longitudinallyr ribbed, the ends of adjacent surfaces being separated by` transverse gaps, at each gap blade means mounted at' the leading edge of each surface with respect to the direction of ow of the fluid-solids mixture, means to ad-v just the blade means substantially parallel to the surface of the table, means to adjust the blade means in aplane substantially normal to the surface of the table and means to tilt the blade means, the blade means overhang-v ing the gap and contacting the ribs at the trailing edge ofl a surface with respect to the direction of dow of the fluidsolids mixtureto present a series of adjustable openings to the flow of the mixture. Y

2. The separating table as claimed in claim 1 in which the ribs overhang the gaps to an extent whereby the ends of the ribs form, in longitudinal section lan angle of about4 135 with a plane parallel tothe surface of the table.

3. The separating table as claimed in claim l in which the `trailing edge ofreach surface is shapedl topromote tranquil flow of the heavy fractions ofthe fluid-solids. mixture thereover.

4. A separating table for. metallurgical fluid-solids mixtures comprising yat least two surfaces longitudinally v ribbed, the ends of adjacent surfaces being separated :by

transverse gaps, at each gap blade means mounted at the leading edge of each surface with respect to the direction of ow of the uid-solids mixture', means to `adjust the.,y blade means substantially parallel to the surface of the. table, means to adjust the blade'means in a planeasubstantially normalto the surfaceof the .table and means to tilt the.blade means, the blade means overhanging` the gap and contacting the ribs at the trailing edge of aV surface with respect to theV direction ofowof the uidsolids mixture to presenta series of adjustable openings to the ow of the fluid-'solids'mixttue, the trailing edge of each surface being shaped to promotetranquil'ow of the heavy fractions of the..fluid-solids'mixtureithereover;`

and the` ribsloverhanging the'gapstozan extent ,wherebyt the ends of the ribs form, in longitudinal section an angle of about 135 with `a plane parallel to thev surface of the table.

5. A separating table for metallurgical duid-solids mixtures comprising at least two surfaces longitudinally ribbed, Kthe ends of adjacent surfaces being separated by transverse gaps, at each gap blade means mounted at the leading edge of each surface with respect to the direction of flow of the Huid-solids mixture, means to adjust the blade means substantially parallel -to the surface of the table, means to adjust the blade means in a plane substantially normal to the surface of the table and means to tilt the blade means, the blade means overhanging the gap and contacting the ribs at the trailing edge of a surface with respect to the direction of ow of the Huidsolids mixture to present a series of adjustable openings to the ow of the duid-solids mixture, the trailing edge 6 of each surface being shaped to promote tranquil ow of the heavy fractions of the fluid-solids mixture thereover and the underside of the blade means being shaped to promote tranquil flow of the duid-solids mixture thereunder.

6. .The separating table as claimed in claim 5 in which the ribs overhang the gaps to an extent whereby the ends of the ribs form, in longitudinal section an angle of about 135 with a plane parallel to the surface of the table.

References Cited in the file of this patent UNITED STATES PATENTS 926,031 Stover June 22, 1909 2,228,607 McDonald Jan. 14, 1941 2,674,374 Elliott Apr. 6, 1954 2,812,060 Hearn Nov. 5, 1957

Images