US2743815A

US2743815A - Continuous centrifugal jig separator

Info

Publication number: US2743815A
Application number: US308800A
Authority: US
Inventors: Goodwin Norris
Original assignee: Centrijig Corp
Current assignee: Centrijig Corp
Priority date: 1952-09-10
Filing date: 1952-09-10
Publication date: 1956-05-01
Anticipated expiration: 1973-05-01

Description

2 Sheets-Sheet 1 Filed Sept. 10, 1952 7'0 Wasfe B/an/(ef I Mafer/a/Refurn MAGNET/C 55mm rok Ore m INVENTOR. Nor/"i5 Gooa'wm May 1, 1956 N. GOODWIN 2,743,

CONTINUOUS CENTRIFUGAL JIG SEFARATOR Filed Sept. 10, 1952 2 Sheets-Sheet 2 INVENTOR. Nor/"is Goodwin BY a United States Patent .Norris Goodwin, San Francisco, Calif, assignor to Cen- 'trijig Corporation, San Francisco, -Calif., .acorporation of California Application September 10, 1952, Serial No. 308,800

14 Claims. (0]. 209-2ll) The present invention relates to methods and apparatus for the separation of minerals and particularly, the separation of minerals of similar particle size but different specific gravity.

In the concentration and separation of minerals it is frequently very desirable to selectively remove a heavy mineral from a lighter mineral where the heavy mineral is in relatively small proportion to the volume of the lighter mineral. Accordingly, it is an object of the present invention to provide both a method and the apparatus for accomplishing such separation with exactness and with a continuous operation.

Also, due to the very fineness of particle size, many of the existing means and apparatus for the separation of minerals become inoperative in ordinary hydroseparatory processes. It is extremely difficult to handle fine mesh sizes of particles because, in most instances, the forces which are brought to bear to accomplish separation do not perform accurately, if they perform at all, on small particle sizes. One of the important objectives of the present method and apparatus is to provide commercial means for accomplishing complete and definitive separation, regardless of the fineness of the particle size.

Among the most available and widely used methods and apparatus for classifying heavy grains from light grains with respect .to their relative specific gravity, are those which employ a dilated or semistationary bed media. Examples of these are the pulsated beds of jigs, the shaker bed of the shaking table, pan, rocker and the like, and the stirred or vibrated bed of the kieve and sluices. All of these employ a bed which remains substantially in position and which represents a media having a specific gravity intermediate of the specific gravity of the particles to be recovered and those which belong to waste. The media remains in one place and is .dilated to the extent that the particles remain in substantially rolling contact with one another with just enough liquid to fill the interstices. The life and activity of such beds are maintained by movement of the bed, which, itself, does not change location.

It has long been desirable to bring the benefits of dilated or semistationary beds into operation with centrifugal separators. However, until the present invention, no satisfactory method or apparatus for accomplishing this objective had been developed.

An object of this invention, therefore, is to provide a method and means for obtaining the benefits of a dilated or semistationary bedded media in combination with a free vortex separation to accomplish continuous and selective separation based upon differences of specific gravity.

It is a further object of the present invention to provide such a method which will have a continuously replenished bedded media to accomplish the separation.

Inasmuch as it is frequent that theheavy mineral exists as a very small percentage of the total slurry, the outflow, of necessity, will be greatly in excess in volume of that of the outflow of values and bedded media. Also, it is apparent that the very nature of the recovered values and bedded media to be withdrawn willhave a high pulp 2,743,815 Patented May 1, 195.6

ice

density which makes the problem of cutting down the rate of withdrawal or controlling the rate of outflow, extremely diflicult. vit is an object of the present invention to provide a valving means which will control the rate of outflow without the use of restricted orifices which tend to plug at low rates of flow. It is likewise 'an'object to provide a withdrawal flow control means which will control high density material of small volume "at a small rate of flow with unrestricted outlet orifices.

The methods of the present invention are not to be confused with the sink-float method where the artificially weighted liquid added to the pulp provides themedia of intermediate specific gravity in which the heavier particles sink by gravity and the lighter particles float so that they may be skimmed off. Also, in the sink-float method, there is no penetration of a bedded media by the heavier particles, such as is disclosed herein.

Further objects are clearly apparent to those skilled in the art and will become more apparent, not only bythe disclosures herein, but by actual experience in operations following them.

Referring now to the drawings:

Figure 1 illustrates, schematically, the operation .of the separating apparatus used to perform the method and to practice the process disclosed herein.

Figure 2 is a diagrammatic rendering ofthe valve means for controlling the outflow.

Figure 3 is a flow diagram of the complete separation and recovery cycle.

Figure 4 is a diagrammatic flow sheet for a dual continuous operation, in which the bedded media is recovered substantially completely, the heavyminerals are recovered individually, and the lighter minerals removed substantially completely.

Figure 5 is a diagrammatic view of the apparatus showing adjustable outlet means at the central portion of the apparatus.

The apparatus used for describing the centrifugal separating method of the present invention and shown in the drawings consists of a cylindrical vessel which is generally designated as 10. Adjacent the upper portion thereof is an entrance port 11. A chamber 12 is formed by the horizontal wall 14 which has a central opening 15. The chamber 12 thus defined is known and referred to as the feed zone. Suspended downwardly through the central opening 15 is an axially mounted shaft 16 which is mounted for rotation and may either be driven directly or through drive pulleys 17 as indicated on the drawings. The drive for the shaft 16 may be of any suitable type but must be so arranged that the speed of rotation may be varied as desired and rotate at a constant speedafter the setting. On the depending end of the shaft 16 within the vessel 10 is mounted a solid baflle impeller 21 consisting of a solid circular baffle plate 18 and having upstanding radial vanes 20. The entire upper surface of the solid baffle impeller may be armored with rubber or plastic materials to minimize abrasion. It is also to be understood that the vanes 20 may be vertical or may be sloped or curved instead of radial. The precise shape of the blades is only important as a refinement of the purposes involved.

It will also be observed that there is only a slight clearance between the upper edges of the vanes 20 and the lower surface of the horizontal baffle 14. This is determined by the largest size particle in the material to be treated so that it may pass therebetween without difiiculty. It is also to be observed that the impeller 21 extends to a point adjacent the inner face of the wall of vessel 10 so that the only entrance to the chamber below is through the peripheral space 19. The space within the chamber defined by the horizontal wall 14 and the solid plate 18 of the rotating impeller assembly 21 which space is indicated as 23, is called the pumping zone.

The chamber below the rotating impeller assembly 22 is a large open chamber 24 known as the separatory zone. In the bottom thereof is an axially located, truncated cone 25 whose sides slope to a base terminating adjacent to the wall of the vessel 10. The top portion of the truncated cone 25 may be provided with an axial collar 26 which defines an outlet opening 27 leading to a discharge pipe 28. The vessel also has an additional discharge outlet 30, which may either be tangential or radial with respect to the outer wall. If the outlet is tangential it should be located in conformity with the direction of rotation so as to produce a minimum of turbulence.

Adjacent this outlet and forming a part thereof is a spacial flow control valve generally designated as 31 and which is diagrammatically shown in Figure 2. it is to be noted that material entering outlet 30 is under considerable pressure due to the centrifugal forces generated in the vortex system established in w. The full flow coming from outlet 30 leads to an inlet pipe 32. Pipe 32 branches in the form of a T into

pipes

33 and 34, all of which have the same diameter as pipe 32. These two branches lead into individual chambers 35 and 31), respectively. Outlet pipes 33' and 34' meet and form a T with line 37 which may lead to a magnetic separator or other suitable device for the separation of concentrates from blanket material as hereinafter described. Within the chambers 35 and 36 and connecting the flow between

pipes

33 and 33 and 34 and 34 are tubular rubber diaphragms 4i) and 41, respectively. These diaphragms separate the heavy granular pulp discharged at 38 from the water or other liquid 42 which is contained Within the vessels 35 and 36. There is a line 43 connecting'the two vessels so that the clear water 42 is free to flow between them. Interposed in this line is a regulating valve 44 by means of which the amount of clear water flowing between the two vessels can be regulated and set. In other words, the regulation and control of the flow of thick, coarse grained pulps passing out at 30 can be obtained with a clear sediment-free flow of fluid through regulating valve 44.

Butterfly valves

45 and 46 are located at the T juncture at the inlet and outlet, respectively. These valves are mechanically interlocked so that they move together and are intermittently reversed by mechanical, electrical, or hydraulic means (not shown), which causes the

diaphragms

40 and 41 to alternately fill and expel. The material in lines 33 and 34' can only flow out at the rate the clear fluid 42 is displaced, which rate is controlled by valve 44. The valve provides a steady flow at any volume, which has heretofore been quite impossible where the pulp, as here, is in part at least of a coarsely granular nature and at high pressure and density, but frequently with a small rate of flow. Valves 51 are provided for each of the vessels 35 and 36 so that clear water or other liquid may be added or removed as desired.

In describing the operation of the apparatus and the steps of the method herein disclosed, reference will be made to Figure 3 which is a flow diagram of the simplest possible complete operation. It will be observed that there is nothing in the separatory zone 24 of the device 10 which interferes with or adds to the movement of the material undergoing classification from the time it enters the separatory zone through the peripheral channel 19 at a fixed angular velocity. The material enters the separatory zone with a minimum of turbulence and free of eddys. Accordingly, the device is of the free vortex type in contrast with the forced vortex type.

For purposes herein, a forced vortex will be considered as a rotating fluid system wherein angular velocities are constant from axis to periphery; a free vortex is a rotating fluid system in which angular velocities increase from periphery toward the axis of rotation. It is recognized that this is broader definition than usual in texts on hydraulics, but is adopted to simplify the description, In

addition, the free vortex differs from the forced vortex in that the fluid does not revolve as a solid. In the free vortex a fluid system is established in which (internal friction being ignored) the actual R. P. M. of a given particle increases from the periphery to any point nearer the axis of rotation. To establish such a system, fluid under head pressure and of high velocity is introduced adjacent the inner periphery of the vessel and is forced to travel inwardly in a tightening spiral to a point or zone, closer to the axis of rotation than that at which it enters the separatory zone. The path of travel may be likened to a watch spring wherein the travel starts at the outer free end and moves inwardly. One may further visualize a free vortex as a system composed of a series of concentric stream cylinders whose axes are common with the axis of rotation. A point on any one cylinder may be traveling the same number of feet per minute as a point on any other cylinder, but as the radius of all cylinders decreases inwardly, each inner cylinder is traveling at a greater R. P. M. than its outer neighbors. As is natural in such free vortex systems, the fluid system produces an axial column of air.

Since the diameter of the vessel 10 may vary, it is not practical to express the operation in terms of R. P. M. of the impeller. The angular velocities required to establish the free vortex and separation depends on several factors such as the difference in particle size, the difference in specific gravity between the minerals to be separated and the like, but for all practical purposes a minimum peripheral velocity at the point of entry to the separatory zone should be 1,000 feet per minute or more.

In mineral separation it is very desirable to successfully and selectively remove a small percentage of a heavy mineral from a large volume of a lighter mineral. There are numerous instances which could be used to establish this as a truism, but for purposes of illustration, and, further, to illustrate the method of the present invention, the recovery of Scheelite from a gangue of quartz has been selected because nearly all of the problems which have caused trouble in the past appear when this combination is encountered. Scheelite has a specific gravity of 5.9 to 6.1 and quartz has a specific gravity of about 2.65. Despite the wide difference in the gravities of these two components, Scheelite separation at fine mesh sizes has proven exceedingly difficult. This is caused in part by the fact that the mineral itself is very brittle and tends to shatter to very fine particles, which due to their size and shape tend to report with the somewhat coarser silica particles in the ordinary hydro-separatory processes.

To accomplish the separation, the ground ore, in the form of a slurry or pulp of high solid content, is fed through line 47. The optimum pulp density will vary with the type and nature of the ore, but in general a density of from 50% to 70% solids by weight will prove satisfactory. Thinner suspensions may be handled but at the expense of volumetric capacity of a given unit. Into the feed line 48 there is fed a substantial quantity of material having a specific gravity intermediate between the gravities of the two minerals to be separated. This material of intermediate specific gravity is hereinafter referred to as the blanket material, although it functions as a semipermeable membrane, as will be hereinafter described. In the present case the blanket material may be, for example, magnetite, which is magnetic and has a specific gravity of 5.2. The particle size of the blanket material should be approximately the same as the finest particle in the gangue which is to be removed. This is fed in through the line 48 to mix with ore fed in through 47 and together they enter the feed zone 12 through the inlet 11. The quantity added should be several times the volume of the anticipated recovery of the value or min eral, Scheelite, in the present example, which is to be removed together with other heavy minerals. In general, the quantity must be enough to maintain a rapidly rotating bed or blanket in the outermost stream cylinders at all times during operation.

at least four to five particles in depth, but in any event, thick enough to perform its intended function as herein described.

It is well known that in the operation of free vortex devices, the outermost stream cylinders contain the heavy particles with essentially no free water above that required, e. g., to fill the voids. In other words, the particles themselves are in physical contact, but are free to .rotate one upon the other.

In the present operation the mixture which is fed into the feed zone passes downwardly through the axial aperture 15 directly onto theflrotating impeller assembly 21. It is immediately influenced by the rapid rotation of the impeller and contact with the vanes so that a maximum and uniform peripheral or angular velocity will be imparted to all portions of the incoming feed. By introducing the feed through the axial orifice 15, it will be observedthat the feed "enters the pumping zone at a point of lowest peripheral speed in terms of feet per second. It will, therefore, be observed that the rotating impeller 21 operates as a pump and as before indicated, the clearances determining the efliciency ofthis structure as a pur'np.

The velocity or peripheral speed developed by the rotation of the impeller is the result of independent mechanical means and is applied to the fluid internally, that is to "say, within'the body of the vessel itself. The feed is not these feed orifices maybe used if desired. Likewise, the

feed is free of any pump pressure requirements as the operation is not dependent upon the pump pressure at the inlet orifice. The impeller may be rotated atany desired speed and is limited only by thestresses set up in the body of the impeller :itself and the safe operating stresses allowable tor the material from which it is constructed. The material undergoing treatment is forced directly to the 'wall of the cylinder at ta fixed angular velocity and passes downwardly in an arc of 360 in the, passage space 19. :Beyond a certain critical velocity, the centrifugal forces generated will be far greater than the force of gravity and the material will rotate within the separatory zone and will beheld against the vertical walls with a force directly proportional to, the specific gravity of the individual particles involved. The outermost stream cylinder will contain the heavy particles substantially in contact with and rolling upon each other, forming a bed .or blanket of thernagnetiteparticles. In accordance with the "Well-established laws governingthe operation of jigs,

such .a bed or blanket comprises a semipermeable membrane. Materials of equal :or heavier gravity will enter landpass through the bed but minerals of lighter gravity will be crowded out or prevented from penetrating.

As shown diagrammatically in Figure 1, the blanket of magnetite material .50 represents the vertical stream cyl linders adjacent the perimeter of the separatory chamber 24. It is to be noted that in Figure l the particles are shown and distinguished by a difference in size. This is .to be considered as illustrative merely, as in practice the ore and ,the blanket material will be of substantially the same particle size. Separation in this device is based entirely upon individual particle specific gravity and not .on particle size. The heavier particles or those of great- ,est specific gravity, which is the Scheelite in the present example, enter .the blanket material $0 and either pass therethrough or are retained therein. The action of the rotating blanketiill within .the separatory zone resembles or is reminiscent of the activity of the bed of a jig and rejects the material of lesser specific gravity along with the excess water. In this instance the rejected material,

which is the garigu e of quartz moves towards the central portion of the separatory zone and is collected and passes out through'the take-off27 and the line 28.

While the action of the blanket material resembles that of the jig, it is not the same. In this instance the blanket is a whirling mass composed of particles which are in individual rolling contact with each other, whichis maintained active and live by velocity imparted by the impeller 21 and centrifugal force, rather than the pulsation of fluid to maintain the bed inlive condition. The innermost particles of the blanket or bed, because of their faster rotation and greater angular velocity, present a shear zone, with the result that particles of greater specific gravity can easily penetrate the bed, while those of lesser specific gravity are crowded out toward the axis of rotation. It is apparent that the separation can be made with a great deal of control and is much superior to those made by any other method. In addition, an extremely ive and active blanket is being continuously formed and removed during operation, "which is entirely different "from any jig operation heretofore known.

The blanket material, plus its separated and contained mineral of higher specific gravity, is continuously removed through the outlet 30, which outlet is preferably tangential to cause a minimumof disturbanceor change of direction, and is removed through themeteringvalve at a rate equal to the total feed of the blanket material plus the volume of the heavy mineral calculated as being present in the original feed.

As indicated above, withdrawal of the blanket material and its entrained heavier mineral cannot be satisfactorily controlled by varying the size of the outlet orifice. Accordingly, the special flow control valve shown in Figure 2 has been devised which continually operates at full opening. The operation is in the following manner.

The blanket material and its entrained heavier mineral is withdrawn from the device through line 30 and usually this line is at a pressure of plus or minus thirty pounds. As shown in Figure 2, the top butterfly valve45 is directing the full flow into the branch 33, into the vessel 35 and is restrained from any contact with the clear water 42, or any other suitable liquid, by the diaphragm 40. The outlet line 33 being obstructed by the butterfly valve 46, the flow accumulates Within the diaphragm 40, exerting a pressure on the water or other liquid 42, causing it to flow out of line 43 through valve 44 and into the vessel [36. Obviously, the flow of this liquid canonly be at the rate permitted by the adjustment of the valve 44. As the volume increases, the pressure of the liquid within the container 36, forces the rubber diaphragm 41 to squeeze axially and, in so doing, eliminates the accumulation contained within the diaphragm 41, out through line 34'. Since the butterfly valve 46 is open'for this outflow, the full flow continues to be discharged into line 37. The cycle is reversedat regular intervals by reversing the mechanically

linkedbutterfly valves

45 and 46 with any suitable means. The valve operates somewhat in the manner of a reverse pump, but it will be observed that this valve controls the rate of flow without the use of restricting orifices which tend to plug at low rates of how, and withoutthe attendant difficulties of attempting flow control directly on a material of high pulp density. t

Figure 3 shows a complete flow diagram in which the slurry of minerals .to be separated is fed into line 47, while the blanket material comes fromline 48 and the mixture is fed to the separator 10at inlet 11 where it is subject to the actions of the free vortex and the extremely lively and active blanket material. Asbefore indicated, the gangue'is withdrawn centrally of the device 10 and passes out through line 28 to waste. The blanket material plus the value is withdrawn through outlet 30 and goes through flow control valve 31 described above. From this valve it goes through line 37 to a magnetic separator which recovers the values and they are removed by line 53 as concentrates. Blanket material, being magnetic, is easily separated and is removed therefrom by means of line 54 through which it is returned to theinflow system by means of line 48.

It is therefore apparent, that unlike any jigging operation, this blanket material is constantly in circulation in the system and is constantly in movemnt, not only within the chamber 10 itself, but through its continuous withdrawal and addition.

Figure 4 shows a variation of the process in which a more effective means of separation than has previously been known is obtained by using two units in tandem. Here again, the gangue and the value as a slurry enters through the feed line 47 and the blanket material comes into the feed line through line 48. This mixture of a predetermined amount of blanket material and gangue plus value is fed into the vessel 10 through port 11, where it is subjected to the free vortex action at a fixed angular velocity dependent on the rotation of the impeller 22. As the result of this, three zones are established within the separating chamber 24. The first and outermost zone or the layer adjacent the wall will contain all of the heavy mineral constituents of the original ore having a specific gravity greater than the specific gravity of the blanket material. In most instances the amount of this heavy concentrate will be insufficient to form a pure continuous layer of its own and will comprise a layer of mixed heavy minerals and blanket material. The next zone moving toward the axis of the vessel, will comprise a layer of blanket material whose thickness will depend entirely upon the proportion of blanket material fed to the ore from line 48. The third and innermost zone or layer will comprise all of the gangue minerals having a lesser specific gravity than the blanket material. The boundary line between the second and third zones, i. e., between the blanket material and the gangue, will frequently be fuzzy and not as sharp as would be desired. This is due to several factors, such as the presence of gangue minerals having a specific gravity close to that of the blanket material and also to the fact that the pulp density at this point is lower (the percentage of water being higher) and the individual particles of blanket material are not in as close physical contact as required for positive separation.

By following the method which is illustrated in Figure 4, a clean, sharp separation between a gangue and a heavy mineral concentrate may be obtained. The ore which is fed through line 47 has been previously ground to an appropriate size, preferably having a particle size less than one-quarter inch. It is in the form of a pulp or slurry at a pulp density of from 50% to 70% solids by weight. Blanket material at a similar pulp density is introduced through line 48. The mixture then passes into the vessel 10 while it is subjected to the free vortex and live bed. separation. The metering valve 31 is set to allow the removal of all of the material in the first or outermost zone described above, together with a part of the blanket material in the second or intermediate zone. Thus, material passing through the metering valve 31 will contain all of the heavy mineral concentrates and will be essentially free of gangue minerals. As before described, it will then pass immediately by line 37 to the magnetic separator 52 where the concentrates are recovered and discharged through line 53, while the blanket material is collected and returned to the system through line 54.

The materials passing out of the separator 10 through outlet 27 and into dishcarge line 28 will comprise all of the gangue together with a part of the blanket material originally introduced into the system. This product is taken directly to a second and substantially identical unit 10 and enters in the same way at inlet port 11'. The metering valve 31', which functions precisely as before described for valve 31, is set to remove all of the blanket material in the feed with the least amount of gangue material consistent with complete separation. Material passing out of the outlet 27 and into outlet line 28' will comprise pure gangue mineral and may be disposed of as desired.

Since gangue minerals are very seldom magnetic, it is possible to arrange an automatic control for the valve 31.

This is indicated at 55 which is a simple electronic device and responds to the presence of any magnetic material passing through the outlet line 28' to which it is attached. The presence of any magnetic material will automatically adjust the valve 31' to a point at which magnetic material no longer passes out through line 28. However, it is to be understood that such automatic control is not an essential part of this invention.

The material coming through control valve 31' containing blanket material and a minimum amount of gangue is fed by means of line 37' to another magnetic separator 52 in which the magnetic blanket material is recovered and withdrawn by line 54 to join with line 54 for return to the feed, while the nonmagnetic gangue is disposed of through line 28".

As further indication of the widespread utility of the present invention, it is to be noted that there are several instances where mineral aggregates occur in association which will provide all or part of the blanket material required. Such an instance will be found in many of the black sand deposits of the Pacific Coast.

In certain special instances, binary separations may be made without the use of blanket materials and such a separation can be made of barite which has a specific gravity of 4.3-4.6 and chert, which has a specific gravity of 2.6. Complete separation of these two mineral ingredients is possible by using the method described in connection with Figure 4 without the

magnetic separators

52 and 52 and returning the material withdrawn through control valve 31' to the original feed at 11. Barite is sutficiently heavier than chert to form its own blanket and will be recovered in relatively pure form through control valve 31, while cleaned chert will pass out through outlet orifice 27 and line 28'.

In Figure 5 a variation of the outlet for chamber 10 is shown. In this instance, instead of the collar or sleeve 26 there is a separate outlet sleeve 26 which is adjustable as to height or penetration into the chamber 24 of the vessel 10 providing optimum conditions for various materials and cuts. Suitable means such as rubber gaskets 56 are provided to prevent leakage. The diameter of the outlet 26 or 2.6 may be varied to suit specific conditions. The limiting factor is that it must be less than the diameter of the impeller 21.

The use of magnetite, or ferrosilicon, as the added blanket material is an obvious one, but the choice is not limited to these. It is contemplated that synthetic magnetic blanketing materials of any desired specific gravity may be created to accomplish certain kinds of cuts. On the other hand, where the materials to be recovered are themselves magnetic, it is contemplated that galena or other minerals separable by flotation or other means may serve as the blanket material.

The nature of the operation of this device and the methods employed are such, that the unit will operate equally well in the horizontal position as in the vertical position. Therefore, the vertical position shown is merely illustrative and is not to be construed as a limitation.

I claim:

1. The method of selectively separating a heavy mineral from a large volume of lighter mineral, comprising the following steps: forming a slurry of the minerals to be separated having a density of 60% solids by weight, adding thereto a mineral blanket material having a specific gravity intermediate of the specific gravity of the minerals to be separated and a particle size approximating the finest particle of the lighter mineral sufficient to form a blanket at least 4 particles thick in the open chamber, rotating said material to give it a peripheral speed of at least 1,000 feet per minute, peripherally feeding said rotating material into a circular open chamber to permit the formation and maintenance of a free vortex, maintaining a live bed of blanket material adjacent the wall of the open chamber, wherein the particles thereof are in free rolling contact, removing the lighter minerals from the central portion of said free vertex of said chamber, removing the heavier mineral and blanket material from the perimeter of said chamber at the bottom thereof, separating said blanket material from said heavier mineral, and returning the blanket material for reuse.

2. The method of continuously and selectively separating a nonmagnetic heavy mineral of tfine particle size from a large volume of lighter mineral also having afine particle size, comprising the followingsteps: forming aslurry of the minerals to be separated having a pulp density of not less than 50% nor more than v70% solids by weight, adding thereto a mineral magnetic blanket material having a specific gravity intermediate of the specific gravity of the minerals to be separated and 'a particle size approximating the finest particle of the lighter mineral sufficient to form a live bed at least four particles thick in the chamber, rotating said material to give it a peripheral speed of at least 1,000 feet per minute, peripherally feeding said rotating material into anopen cylindrical chamber to permit the formation and maintenance of a free vortex, maintaining a live bed of blanket material adjacent the wall of the open chamber, wherein the particles thereof are in free rolling contact, removing the lighter minerals from the lower central portion of said free vortex of said chamber, removing the heavier mineral and blanket material from the perimeter of said chamber at the bottom thereof, magnetically separating said blanket material from said heavier mineral, and returning the blanket material for reuse.

3. The method of continuously and selectively separating a heavy non-magnetic mineral of fine particle size from a large volume of lighter mineral also having a fine particle size, comprising the following steps: forming a slurry of the minerals to be separated having apulpdensity of not less than 50% nor more than 70% solids by weight, adding thereto a magnetic mineral blanket material having a specific gravity intermediate of the specific gravity of the minerals to be separated and a particle size approximating the finest particle of the lighter mineral sufiicient to form a live bed at least four particles thick in the chamber, rotating said material to give it a peripheral speed of a least 1,000 feet per minute, peripherally feeding said rotating material into an open cylindrical chamber to permit the formation and maintenance of a free vortex, maintaining a live bed of blanket material adjacent the wall of the open chamber, wherein the particles thereof are in free rolling contact, removing the lighter minerals from the lower central portion of said free vortex in said chamber, removing the heavier mineral and blanket material from the perimeter of said chamber at the bottom thereof, adjusting the rate of heavy mineral flow in the withdrawal to accommodate a low rate of flow at full outlet orifice opening, magnetically separating said blanket material from said heavier mineral, and returning the blanket material for reuse.

4. The method of continuously and selectively separating a heavy non-magnetic mineral of fine particle size from a large volume of lighter mineral also having a fine particle size, comprising the following steps: forming a slurry of the minerals to be separated having a density of 60% solids by weight, adding thereto a magnetic mineral blanket material having a specific gravity intermediate of the specific gravity of the minerals to be separated and a particle size approximating the finest particle of the lighter mineral sufficient to form a live bed at least four particles deep in the separating chamber, tangentially feeding said mixture adjacent the top of an unobstructed cylindrical separating chamber at a rate to provide a peripheral speed of at least 1,000 feet per minute to permit the formation and maintenance of a free vortex, maintaining a live bed of said blanket material adjacent the wall of the separating chamber, wherein the particles thereof are in free rolling contact, removing the lighter minerals from the lower central portion of said free vortex in said chamber, removing the heavier mineral and blanket material from the perimeter of said chamber at the bottom thereof, adjusting the rate of heavy mineral flow in the withdrawal to accommodate a low rate of flow at full outlet orifice opening, magnetically separating said blanket material from said heavier mineral, and returning the blanket material for reuse.

5. The method of continuously and selectively separating a heavy magnetic mineral of fine particle size from a large volume of a lighter mineral also having a fine particle size comprising the following steps: forming a pulp of the minerals to be separated having a pulp density of 60% solids by weight, adding thereto a non-magnetic mineral bed material having a specific gravity intermediate of the specific gravity of the minerals to be separated and a particle size approximating the smallest particle size of the lighter mineral sufficient to form alive bed at least four particles thick in the chamber, rotating said pulp to give it a peripheral speed of at least 1,000 ,feet per minute, peripherally feeding said rotating pulp into an open cylindrical chamber to permit theformation and maintenance of a free vortex, maintaining a live bed of said blanket material adjacent the wall of the open chamber, wherein the particles thereof are in free rolling contact, removing the lighter minerals from the lower central portion of said free vortex in said chamber, removing the heavier mineral and blanket material at the bottom of said chamber adjacent the perimeter thereof, separating the non-magnetic blanket material from said heavy mineral by flotation, and returning the blanket material for reuse.

6. The method of continuously and selectively separating a heavy magnetic mineral of fine particle size from a large volume of a lighter mineral also having a fine particle size comprising the followingvsteps: forming a pulp of the minerals to be separated having a pulp density of 60% solids by weight, adding thereto a non-magnetic mineral bed material having a specific gravity intermediate of the specific gravity of the minerals to be separated and a particle size approximating the smallest particle size of the lighter mineral sufficient to form a live bed at least four particles thick in the chamber, tangentially feeding said mixture adjacent the top of an unobstructed cylindrical chamber at a rate to provide a peripheral speed of at least 1,000 feet per minute to permit the formation and maintenance of a free vortex, mantaining a live bed of said blanket material adjacent the wall of the open chamber, wherein the particles thereof are in free rolling contact, removing the lighter minerals from the lower central portion of said free vortex in said chamber, removing the heavier mineral and blanket material at the bottom of said chamber adjacent the perimeter thereof, separating the non-magnetic blanket material from said heavy mineral by flotation, and returning the banket material for reuse.

7. The method of continuously and selectively separating a heavy magnetic mineral of fine particle size from a large volume of a lighter mineral also having a fine particle size comprising the following steps: forming a pulp of the minerals to be separated having a pulp density of 60% solids by weight, adding thereto a non-magnetic mineral blanket material having a specific gravity intermediate of the specific gravity of the minerals to be separated and a particle size approximating the smallest particle size of the lighter mineral sufiicient to form a live bed at least four particles thick in the chamber, rotating said pulp and blanket material to give it a peripheral speed of at least 1,000 feet per minute, peripherally feeding said rotating pulp into an open cylindrical chamber to establish and maintain a free vortex, maintaining a live bed of said blanket material adjacent the wall of the open chamber, wherein the particles thereof are in free rolling contact, removing the lighter minerals from the lower central portion of said free vortex in said chamber, removing the heavier mineral and blanket material at the bottom of said chamber adjacent the perimeter thereof,

controlling the rate of heavy mineral flow in the Withdrawal to accommodate a low rate of flow at full outlet orifice opening, separating the non-magnetic blanket material from said heavy mineral by flotation, and returning the blanket material for reuse.

8. The process of claim 3 wherein the central withdrawing orifice for the lighter mineral may be adjusted vertically.

9. The process of claim 7 wherein the central withdrawing orifice for the lighter mineral may be adjusted vertically. I

'10. The process of claim 3 wherein the central withdrawing orifice for the lighter mineral may be varied in diameter but shall not be as large as the means for ini tially rotating said pulp.

11. The process of claim 7 wherein the central withdrawing orifice for the lighter mineral may be varied in diameter but shall not be as large as the means for initially rotating the pulp.

12. A valve for regulating the flow of high density granular material by regulation of an uncontaminated liquid, comprising an inlet and an outlet, two channels of flow through the valve having equal diameter with the inlet and outlet, a liquid chamber surrounding a portion of each channel, a line connecting the liquid chambers permitting liquid to flow from one to the other, a valve in said line controlling the rate of liquid flow, an elastic tube forming a portion of the channel within each liquid chamber separating the granular material from the liquid, interlocking means at the inlet for directing the flow of granular material into one channel While at the outlet expelling the contents from the other channel, and means for intermittently reversing said interlocking means.

13. The method of controlling the outflow of heavy minerals and bed material from a separator where the heavy mineral has been separated by the action of a free vortex and a live and active bed material, including the steps of diverting the outflow through one of two channels at the inlet to accumulate a volume of said -12 flow, accumulating said volume in a resilient tube" in a confined space; displacing liquid as the volume increases, transferring the displaced liquid to a second confined space through which passes the other of the two channels having a similar resilient tube, expelling the accumulated volume of flow in the tube of the second channel by the pressure of the increased volume of liquid and delivering the same to the outlet, and interlocking the channel inlets and outlets to alternate the diversion of the outflow.

14. The method of controlling the outflow of heavy minerals and bed material from a separator where the heavy mineral has been separated by the action of a free vortex and a live and active bed material, including the steps of diverting the outflow through one of two channels at the inlet to accumulate a volume of said flow, accumulating said volume in a resilient tube in a confined space, displacing liquid as the volume increases, transferring the displaced liquid to a second confined space through which passes the other of the two channels having a similar resilient tube, regulating the rate of outflow at the outlet by adjusting the amount of liquid passing between said confined spaces, expelling the accumulated volume of flow in the tube of. the second channel by the pressure of the increased volume of liquid and delivering the same to the outlet, and interlocking the channel inlets and outlets to alternate the diversion of the outflow.

References Cited in the file of this patent UNITED STATES PATENTS 1,669,820 Grant et al May 15, 1928 2,543,689 Driessen Feb. 27, 1951 2,623,637 Fontein Dec. 30, 1952 OTHER REFERENCES Quarterly of the Colorado School of Mines, January 1948, volume 43, number 1, pages 3642. (Copy in Division 55.)

Journal of the Institute of Fuel, December 1945, volume 19, number 105, pages 33-45pg. 37 of particular importance. (Copy in Scientific Library.)

Claims

1. THE METHOD OF SELECTIVELY SEPARATING A HEAVY MINERAL FROM A LARGE VOLUME OF LIGHTER MINERAL, COMPRISING THE FOLLOWING STEPS: FORMING A SLURRY OF THE MINERALS TO BE SEPARATED HAVING A DENSITY OF 60% SOLIDS BY WEIGHT, ADDING THERETO A MINERAL BLANKET MATERIAL HAVING A SPECIFIC GRAVITY INTERMEDIATE OF THE SPECIFIC GRAVITY OF THE MINERALS TO BE SEPARATED AND A PARTICLE SIZE APPROXIMATING THE FINEST PARTICLE OF THE LIGHTER MINERAL SUFFICIENT TO FORM A BLANKET AT LEAST 4 PARTICLES THICK IN THE OPEN CHAMBER, ROTATING SAID MATERIALS TO GIVE IT A PERIPHERAL SPEED OF AT LEAST 1,000 FEET PER MINUTE, PERIPHERALLY FEEDING SAID ROTATING MATERIAL INTO A CIRCULAR OPEN CHAMBER TO PERMIT THE FORMATION AND MAINTENANCE OF A FREE VORTEX, MAINTAINING A LIVE BED OF BLANKET MATERIAL ADJACENT THE WALL OF THE OPEN CHAMBER, WHEREIN THE PARTICLES THEREOF ARE IN FREE ROLLING CONTACT, REMOVING THE LIGHTER MINERALS FROM THE CENTRAL PORTION OF SAID FREE VORTEX OF SAID CHAMBER, REMOVING THE HEAIVER MINERAL AND BLANKET MATERIAL FROM THE PERIMETER OF SAID CHAMBER AT THE BOTTOM THEREOF, SEPARATING SAID BLANKET MATERIAL FROM SAID HEAVIER MINERAL, AND RETURNING THE BLANKET MATERIAL FOR REUSE.