US3390770A - Rod screen - Google Patents

Rod screen Download PDF

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Publication number
US3390770A
US3390770A US465044A US46504465A US3390770A US 3390770 A US3390770 A US 3390770A US 465044 A US465044 A US 465044A US 46504465 A US46504465 A US 46504465A US 3390770 A US3390770 A US 3390770A
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US
United States
Prior art keywords
screen
rods
rod
particles
box
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US465044A
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English (en)
Inventor
Fahlstrom Per A H H Son
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Boliden AB
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Boliden AB
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Filing date
Publication date
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
    • B07B—SEPARATING SOLIDS FROM SOLIDS BY SIEVING, SCREENING, SIFTING OR BY USING GAS CURRENTS; SEPARATING BY OTHER DRY METHODS APPLICABLE TO BULK MATERIAL, e.g. LOOSE ARTICLES FIT TO BE HANDLED LIKE BULK MATERIAL
    • B07B1/00—Sieving, screening, sifting, or sorting solid materials using networks, gratings, grids, or the like
    • B07B1/12—Apparatus having only parallel elements
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
    • B07B—SEPARATING SOLIDS FROM SOLIDS BY SIEVING, SCREENING, SIFTING OR BY USING GAS CURRENTS; SEPARATING BY OTHER DRY METHODS APPLICABLE TO BULK MATERIAL, e.g. LOOSE ARTICLES FIT TO BE HANDLED LIKE BULK MATERIAL
    • B07B1/00—Sieving, screening, sifting, or sorting solid materials using networks, gratings, grids, or the like
    • B07B1/46—Constructional details of screens in general; Cleaning or heating of screens
    • B07B1/4609—Constructional details of screens in general; Cleaning or heating of screens constructional details of screening surfaces or meshes

Definitions

  • the present invention relates to a method of separating fine particles into fractions according to absolute grainsize by screening said particles between rods moving in relation to one another.
  • the invention is more especially related to finely pulverized dry or slurried ore material subjected to upgrading.
  • the particles are divided up according to particle size in a vibratory screen provided with a bed of freely lying rods between which the charge passes.
  • the rods lie longitudinally in a sloping-preferably rectangular-screening frame, the bottom of which is provided with a number of support members. Collection pockets for various fractions are located under the frame.
  • the mean grain size of material passing through the rod bed increases with the distance from the feed end of the screen.
  • the bed is made up of a number of layers "ice of rods e.g. say 10-26 layers.
  • the height of the bed is increased as the grain size distribution in the feed material becomes wider.
  • the length of the rods is selected according to the screening capacity and the degree of fractionation required.
  • the diameter of the rods is usually from 5 mm.
  • the rods are also possible to arrange the rods at right angles to the longitudinal direction of the screen and to use longitudinal support beams in the sloping screen frame for the purpose of supporting said rods.
  • Another possible arrangement of the screen rods according to the invention is to position the rods alternately in the longitudinal and lateral direction of said screen frame thus forming a three-dimensional gridwork of movable rods.
  • the separating ability of the screen can be adapted within wide limits by suitable choice of amplitude, frequency and direction of the vibrating movement which is imparted to the rod screen.
  • amplitudes in the range of 0.5-5 mm. and frequencies of 1000-3000 vibrations per minute are usually selected.
  • the desired result can also be achieved in a slowly rotating and possibly vibrating barrel provided with a bed of rods onto which the material is fed from one end and from above without being subjected to pressure.
  • Finely divided material can easily be screened, using the arrangement according to the invention, down to 0.05 mm.
  • an initial change having a maximum particle size of for example 0.5 mm. particles over 0.1 mm. can be separated for regrinding whereas the finer particles are separated into fractions from 0.05 to 0.1 mm., which is the common requirement within the flotation technique.
  • the described invention is therefore, particularly useful in grinding circuits concerned with the fine grinding of ore.
  • FIGURE 1 diagrammatically shows a longitudinal section through one embodiment of a rod screen according to the invention
  • FIGURE 2 shows a cross section through the rod screen according to FIGURE 1
  • FIGURE 3 shows one example of how two rod screens according to the invention can be included in a grinding circuit.
  • the rod screen shown in FIGURES 1 and 2 consists of a sloping screen box having two parallel side walls 1, 2, two end walls 3, 4, one roof 5 and a screen bottom 6 of a type known per se, e.g. a fine mesh wire net stretched onto a steel frame.
  • a vibrator 12 of a type known per se is arranged on a support structure projecting from the side walls 1, 2 of the screen box, which support structure consists of side walls 9 and 10 and a transverse beam 11, and which vibrator 12 is constructed for a frequency of for example 1000-3000 vibrations per minute and an amplitude of 0.5-5 mm.
  • a number of collccting pockets 1317 intended for gathering fractions of the screened material is situated under the screen bottom 6 immediately adjacent to the same but without coming into direct contact with it.
  • the vibrator 12 On operating the screen the vibrator 12 is set into motion after which the material to be screened is fed into the screen box in the direction of arrow 18.
  • the fine charge endeavours to take the shortest route down through the screen bed and is collected in the pocket 13 adjacent to the feeding position whereas particle fractions of increasing grain size are collected in turn inthe following pockets whereby the coarsest fraction is collected in the lowest pocket 17to the right in FIGURE 1.
  • Five collecting pockets have been selected in the shown embodiment but naturally the number of pockets can be varied. As a rule at least two pockets are preferred in spite of the fact that in principle it is also possible to arrange only one pocket and to allow the oversize to pass out from the screen box through an outlet disposed in the end wall 4 of said box.
  • FIGURE 3 shows a schematic drawing of a screening system including two rod screens according to the invention included in a closed wet grinding circuit.
  • An aqueous pulp consisting of ore particles intended for grinding is fed through an inlet conduit 19 into a mill 20.
  • the ground pulp is then passed from the outlet 21with the assistance of a pump 22-through a conduit 23 to a first rod screen 24 and is there separated into a fine fraction-collected in a pocket 25-and a coarse fractioncollected in a pocket 26.
  • the coarse fraction is returned from pocket 26 via a return conduit 27 to the mill inlet 19 and is combined with the pulp fed into the mill.
  • the fine fraction is passed from pocket 25 through a conduit 28 to a second rod screen 29 of similar construction to rod screen 24, where it is separated into a finished product which is collected in a pocket 30 and led away through an outlet conduit 31 for further treatment, whereas the coarse fraction is collected in a pocket 32 and returned to the mill inlet 19 via a return conduit 33.
  • the drawings only show representative embodiments of the rod screen according to the invention and how it can be used in a two-stage process in a grinding circuit. As was mentioned earlier it is possible to provide the rod screen with several collecting pockets from which thevarious fractions can be directed to different desired points in the grinding circuit.
  • the rod screen can also be combined with other separating devices of types known per se, for example cyclones and common vibratory screens.
  • the rod screen according to the invention can be used for dry screening as well as wet screening although it has its greatest usefulness when wet screening ore material.
  • dry screening it is also within the scope of the invention to feed in the granular charge to be screened with compressed air from the underside of the screen and to arrange in the roof of the screen box a number of suction hoods distributed along the longitudinal direction of said screen box for collecting the airborn particle fractions.
  • rods 8 placed in the longitudinal direction of the screen box to arrange rods lying at right angles to the longitudinal direction of said box and to use longitudinal support members for supporting the same.
  • An apparatus for separating a fine particulate mate rial according to particle size comprising a box extending substantially horizontal and having two side walls and two end Walls; a screen support member disposed in said box at substantially the bottom thereof; a plurality of rods freely arranged on said support member in successive contacting layers, each of said layers comprising rods which are contiguous and in parallel relationship, and which occupy the full extent of the distance between said end walls and said side walls; and vibrating means connected to said box to cause the rods to move relative to each other and to said support member to permit a portion of material introduced into said box from above said rods to pass through said'rods and said support member.
  • said support member slopes in the longitudinal direction of said box and is divided transversely into at least two sections, each having rod layers disposed the-rein, said rods successively decreasing in diameter from section to section in the downward longitudinal direction of said box, said material being introduced over the uppermost end wall of said support member.

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  • Combined Means For Separation Of Solids (AREA)
US465044A 1964-06-24 1965-06-18 Rod screen Expired - Lifetime US3390770A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
SE7721/64A SE301619B (no) 1964-06-24 1964-06-24

Publications (1)

Publication Number Publication Date
US3390770A true US3390770A (en) 1968-07-02

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
US465044A Expired - Lifetime US3390770A (en) 1964-06-24 1965-06-18 Rod screen

Country Status (4)

Country Link
US (1) US3390770A (no)
FI (1) FI46329C (no)
NO (1) NO119163B (no)
SE (1) SE301619B (no)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3938664A (en) * 1972-08-23 1976-02-17 United Kingdom Atomic Energy Authority Sieves

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US770079A (en) * 1903-12-21 1904-09-13 George Fair Potato or fruit sorter.
US1031659A (en) * 1911-04-04 1912-07-02 William L Muender Table.
US1905417A (en) * 1930-04-04 1933-04-25 Charles H Macdonald Rod mill
US2068783A (en) * 1932-09-29 1937-01-26 Carl A Wendell Apparatus for separating materials
US2080884A (en) * 1937-05-18 anderson
US2922588A (en) * 1955-02-17 1960-01-26 Hoesch Robert Vibratory material comminutor
US3064812A (en) * 1956-07-28 1962-11-20 Wehner Albert Pervious surface

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2080884A (en) * 1937-05-18 anderson
US770079A (en) * 1903-12-21 1904-09-13 George Fair Potato or fruit sorter.
US1031659A (en) * 1911-04-04 1912-07-02 William L Muender Table.
US1905417A (en) * 1930-04-04 1933-04-25 Charles H Macdonald Rod mill
US2068783A (en) * 1932-09-29 1937-01-26 Carl A Wendell Apparatus for separating materials
US2922588A (en) * 1955-02-17 1960-01-26 Hoesch Robert Vibratory material comminutor
US3064812A (en) * 1956-07-28 1962-11-20 Wehner Albert Pervious surface

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3938664A (en) * 1972-08-23 1976-02-17 United Kingdom Atomic Energy Authority Sieves

Also Published As

Publication number Publication date
NO119163B (no) 1970-03-31
FI46329B (no) 1972-11-30
SE301619B (no) 1968-06-17
FI46329C (fi) 1973-03-12

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