US3326373A - Ore concentration - Google Patents

Description

W. H. LANG June 20, 1967 ORE CONCENTRATION 6 Sheets-Sheet 1 Filed May 7, 1964 Inventor June 20, 1967 w. H. LANG 3,326,373

ORE CONCENTRATION Filed May 7, 1964 I5 Sheets-Sheet Inventor warren Lang,

June 20, 1967 w. H. LANG 3,326,373

ORE CONCENTRATION Filed May 7, 1964 5 Sheets-Sheet 3 II w l HM" dllIML I Inventor N Warren Lang United States Patent Ofilice 3,326,373 Patented June 20, 1967 3,326,373 ORE CONCENTRATION Warren H. Lang, Fort Meade, Fla., assignor to Swift & Company, Chicago, Ill., a corporation of Illinois Filed May 7, 1964, Ser. No. 365,721 6 Claims. (Cl. 209-18) This invention relates to a method and apparatus for the separation of granular mixtures containing ingredients of varying densities and particles size and, more particularly, to the separation of phosphate ore from mixtures containing such ore and the concentration of phosphate ores.

A continuing eifort has been exerted in the phosphate industry over :a period of time to develop more economical means for the separation and recovery of phosphate ore from reagentized mixtures containing such ore. Phosphate ore, and particularly the finer fraction of the ore, must be obtained in a large quantity by the most economical technique inasmuch as the price obtainable for the ore is so low as to exert a substantial pressure on the cost to recover the ore. As a result, any improvement in recovery efliciency, lowering of labor costs, extending the life of recovery equipment, or reduction in the maintenance required in the operation of such equipment is of profound importance to the phosphate producer.

Manufacturing procedures for the recovery of high grade phosphate material have involved the use of flotation, tabling, and various types of separators, including gravity separators, troughs, sluices, and the like. While many different flotation reagents have been employed, and diverse kinds of separators have also been used to separate the valuable mineral material from the gangue or siliceous fraction, these procedures and apparatus have all possessed shortcomings which have emphasized the need for a simpler, more economical, and more efficient method and apparatus for recovering the ore from the slurry.

It is accordingly an object of this invention to provide an improved method for recovering high grade phosphate material from phosphate ore in admixture with impurities such as sand which method is simple, more economical, and more eflicient than previously known methods.

Another object of the invention is the provision of apparatus for the recovery of a high percentage of high grade phosphate ore from mixtures containing such ore, which apparatus requires a minimum of operator attention.

Still another object of the invention is to provide a method for continuously separating and concentrating from phosphate ore slurry a high percentage of the phosphate material contained therein.

Additional objects of the invention, if not specifically set forth herein, will be readily apparent to those skilled in the art from the detailed description of the invention which follows.

Generally the invention is concerned with an improved method for separating valuable mineral constituents from a liquid slurry containing such constitutents along with less valuable ingredients. Also a part of the in vention is novel apparatus for effecting such separation and concentration. The method has particular application to the handling of reagentized, granular mixtures dispersed in a slurry. By means of the invention it is possible to obtain a cleaner, more eflicient, and rapid se aration of the valuable concentrate from the less valuable tails in a reagentized pulp of phosphate ore, for example. The apparatus employed for effecting separation of the phosphate fraction from the reagentized slurry is economical, has a minimum of moving parts, subject to wear and breakdown, and requires little operator attention.

More particularly, the invention comprises steps of forming a body of reagentized pulp containing phosphate ore and gangue in an agitation and flotation zone, subjecting said pulp to agitation and aeration to produce a float phase and a nonfioat phase guiding the nonfioat phase from said zone and conducting said float phase to a pinched sluice assembly where the float material is further separated into a rougher concentrate and cleaner tailings.

Advantages and unique features of the invention will be apparent to those skilled in the art from a reading of the d tailed description in conjunction with the accompanymg drawings in which similar reference characters refer to similar parts and in which:

FIGURE 1 is a perspective view partly in section of an embodiment of the invention.

FIGURE 2 is a plan view of portions of the apparatus of FIGURE 1.

FIGURE 3 is a cross-sectional view of a portion of the apparatus of FIGURE 1.

FIGURE 4 is a cross-sectional view taken through FIGURE 3 along the line 4-4.

FIGURE 5 is a partial cross-sectional view, similar to FIGURE 3, showing the apparatus in operation.

A liquid pulp or slurry containing phosphate particles and sand is introduced into the apparatus through feed manifolds 10 and 11 attached to a source of slurry supply (not shown) through conduits 12 and 13. Along the conduits at regular intervals of about one foot are nozzles 14 disposed downwardly to feed the pulp to the apparatus. Running parallel to the feed conduit on either side thereof are two water supply conduits 15 and 16 which are connected by a T coupling to a source of water supply under pressure through valve 17. Several nozzles 18 about 6 inches apart along each of the water supply conduits provide downwardly disposed high pressure jets. The nozzles are inclined at an angle of about 3 degrees toward the center, having openings of about inch and can be operated using water pressure at a discharge velocity of about 5 0120 feet per second.

Beneath the slurry feed supply and the water jets is a trough or tank generally 20 mounted on a support formed of legs 21 and 22 and a base 23. The trough is roughly trapezoidal in form and is open at the top. The trough includes a base 24, outwardly inclined sides 25 and 26 and ends 27 and 28. At intervals of about every two feet along the base of the trough are solids discharge ports 30 and 31, attached to the trough by couplings 32 and 33 Welded in the sides of the tank. A replaceable, flexible pad 34 is disposed in the bottom of the tank running longitudinally thereof and overlying the bottom of said tank. Baflles 35 and 36 attached to the sides of the trough by means of brackets 37 and 38 run lengthwise of the tank in spaced relationship to the sides of the tank. The baflles include a vertical portion 39 which is serrated (see FIG- URE 4) and an angled portion 40, which extends toward the sides of the trough to form a generally enclosed quiescent solids sink zone 41.

Extending into the quiescent zone and running perpendicular to the length of the trough are a series of pinched sluices 45 and 46. The sluices are made up of a floor or bottom 47, and sidewalls 48 and 49 which converge at an angle of about 25 degrees from the inlet to the discharge end thereof. The sluices are mounted on the sides of the tank by means of hinges 50 and 51 attached to the bottom of the sluice and the top edge of the trough and which permit limited vertical movement of the sluices from the horizontal. The sluices are ganged by tangle iron tiebars 52 and 53 running paralle'lto the sides of the trough and beneath the floor of the sluices.

Mounted along the sides of the tank and extending outwardly thereof are support brackets 54 and 55 which support the discharge end of the pinched sluices by bolts 56 and 57. Nuts 58 and 59 are welded to the sluice base providing for adjustment of the angle of decline of the sluice floor from the horizontal. This adjustment device permits a variation of up to about 10 of decline of the sluice floor from the horizontal.

Extending into the discharge end of the sluices are a series of U-shaped splitter blades 60 and 61 which include a base 62 and sides 63 and 64. The floor of the splitter blade extends into the discharge end of the pinched sluice and a lip 65 overlaps the base of the pinched sluice slightly. The several splitter blades are ganged in parallel by a rod 66 which passes through the sides of the splitter and is disposed parallel to the length of the trough. The rod is supported by supports 67 attached to the trough. The stream dividing or entering end of the splitter blade can be raised and lowered by adjusting bolts 69 which bear against the base of the floor of the pinched sluice and engage nuts 70 welded to the floor surface of the splitter blade.

A compartmented receptacle comprising sides 80 and 81 and ends 82 and 83 and having a flanged upper edge 84 is divided longitudinally by a vertical divider 85 which separates the receptacle into two zones 86 and 87. The solid discharge pipes 30 and 31 are connected to and discharged into the tailings zone 86.

The operations (seen best in FIGURE 5) comprises continuously passing reagentized feed at about l40% solids from the slurry supply into the trough. The slurry may contain reagentized phosphate particles of a size in the minus 16 mesh to plus 28 mesh range and non-reagentized sand particles in aqueous suspension. When a body of the slurry or pulp is [formed in the trough, water under high pressure is introduced through the Water nozzles. The nozzles are located at least about 1 inches above the top of the serrated battles and usually about 1 /25 inches above said bafiles and the nozzles are spaced so that the agitating effect of one jet overlaps the agitating effect of each adjacent jet. The water pressure is adjusted to obtain vigorous agitation and aeration in the trough and pressures of about 18-100 p.s.i. and higher have been found very satisfactory. The jets of Water impinge off the bottom of the trough and the flexible pads serve to protect the bottom of the metal tank against the abrasive effect of the gangue forced against the bottom by the force of the jets. The movement within the body of the pulp causes the phosphate particles and a small amount of gangue to be lifted toward the surface. The lifting action is brought about in part by vertically rising currents resulting from the downwardly impinging jet stream and in part by air bubble attachment. As can be seen from FIGURE a flat spray is formed exerting currents running parallel to the bottom of the tank, maintaining continuous movement in the bottom of the tank, thus avoiding any gravity settling of heavy particles.

The sand particles present in the pulp are the more coarse ingredients of the pulp remaining in a suspended state near the bottom of the trough. These coarse sand particles because of the jet action do not settle out, but rather remain in suspension and form a lower phase which acts much like a high density liquid which seeks its own level and flows to any discharge below its surface. The sand discharge ports along the bottom of the trough permit a continuing discharge of this layer from the trough.

Usually abuot 75-95% of the gangue can be removed at this step in the process.

The flow of reagentized phosphate particles and fine non-reagentized sand particles to the surface of the pulp, as is shown in FIGURE 5, is in the direction of the serrated bafiles. The phosphate ore and fine non-reagentized sand particles flow over the battle into the quiescent V- shaped zone 41 formed by the baflle and the sides of the trough. In this zone, which is relatively isolated, from the turbulence in the main part of the trough, the small amount of gangue which is carried over is separated by gravity and falls back into the bottom of the trough. The reagentized phosphate along with some very fine gangue flows across the quiet water area into the head of the pinched sluices. Even at the inlet end of the pinched sluices the liquid has begun to stratify into three layers, including a top layer of float material, a middle layer largely Water, and a bottom layer of fine particulate nonfloat material.

Inasmuch as most of the nonfioat material has been eliminated prior to introduction of the liquid into the convergent sluices, it is possible to reduce substantially the angle of declination of the floor of the sluice and thereby reduce the speed of laminar flow as compared to the operation of such sluices suggested heretofore, yet still avoid particle interference and sand barring. Sand barring results in the development of a pile of nonfloat material on the surface of the sluice floor and this in turn causes turbulence at the interface between the nonfloat and Water layers. The Water layer and topfloat layer move at a higher velocity than the nonfioat, causing the accumulated nonfloat material to be caught up and swept out with the topfloat material. Since there is a minimum amount of coarse nonfloat material, it is only necessary in utilizing the pinched sluices to decline the floor of the sluices at an angle of about 7-8 degrees from the horizontal to maintain transquil laminar flow and yet insure good stratification of layers. Thus it is possible to employ a lower stream velocity than has been suggested heretofore in the use of pinched sluices and yet avoid sand barring.

As the liquid flows down the sluice the depth of the liquid in the sluice increases and at the discharge end of the sluice the stream is divided by the splitter. The floor of each sluice trough extends about inch past the terminal ends of the converging sidewalls and the separating edge of the splitter blade lies above the sluice floor, extending into the terminal end of the trough slightly. The splitter blade or trough is disposed in a plane of Stratification at right angles to the direction of flow of the liquid and the discharge from the sluice is divided with the rougher concentrate passing over the top of the splitter and into a receptacle for concentrate while the relatively clean tailings passesbeneath the splitter blade to a receptacle for gangue and trailings.

By subjecting the slurry to turbulent agitation and aeration utilizing high pressure liquid jets and drawing off the major portion (-95%) of the gangue before passing the floated material to a quiescent zone for further gangue dropout prior to initiation of the tranquil laminar flow to induce Stratification, a much more eflicient and rapid separation of reagentized phosphate is provided. In addition, when treating coarser fractions, those in the minus 14 to +28 mesh range, the concentrated phosphate ore is much cleaner than ores produced by equipment known heretofore. The apparatus required is compact, requiring a minimum amount of space, yet can be operated continuously to process a large volume of slurry. For example, an apparatus having a trough approximately 8 feet in leng-thabout 2 feet wide and about 4 inches to 1 foot deep equipped with 4 pairs of discharge ports and 20 pairs of pinched sluices about 10% inches long, each having an inlet about 4 /2-6 inches wide, and converging to a width at the discharge end of about 1% inches, has been employed to recover and concentrate reagentized phosphate ore from slurry at a feed rate in excess of about 275 tons per day. The pinched sluices decline from the horizontal about 5-8 and the sides of the sluices converge at an angle of about 17-30 and preferably about 25. Larger and smaller angles both with respect to declination and convergence can be employed with varying degrees of speed of operation and efliciency.

A typical example of the operation of the apparatus of the invention involved feeding a slurry to the device and measuring the degree of separation at various points in the operation of the process. The following table shows the percent bone phosphate of lime against phosphorus pentoxide and the percent silicon dioxide of fractions obtained at various stages of the process.

In the experiment 91.5% of the gangue was discharged through the discharge ports in the aeration and flotation zones and 1.9% of the gangue was discharged beneath the splitter blade at the discharge end of the pinched sluices. Only 6.6% of the finer gangue material was included in the rougher concentrate.

Obviously many variations and modifications of the invention as hereinbefore set forth may be made without departing from the spirit and scope thereof and accordingly only those limitations should be imposed as are indicated in the appended claims.

I claim:

1. Apparatus for the separation of valuable minerals from a slurry of said minerals and gangue, said apparatus including a flotation cell for maintaining a body of slurry, said cell comprising an elongated shallow container having upwardly and outwardly inclined sidewalls, oppositely inclined baflies beneath the surface of said body of slurry positioned parallel to and in spaced relation to the upper portion of said sidewalls to form iso lated quiescent zones in said container lengthwise thereof wherein a portion of gangue is dropped; discharge means located along the lower portion of said sidewalls to remove nonfloat fluid from the lower portion of said container; slurry supplying means disposed above said container to provide a continuous flow of slurry into said container; liquid jet means adapted to impinge jets of liquid against the surface of the slurry centrally of said container and produce aeration and agitation within said slurry and cause float materials and a portion of gangue to rise to the surface of said slurry in said container; a plurality of pinched sluices arranged in parallel along the sides of said container extending into said quiescent zones to receive overflow of float material from said container; splitter blades disposed across the discharge ends of said pinched sluices with the ends of said blades intersecting said sluices to divide the discharge from said sluices; and receptacles beneath said blades to receive the discharge passing on opposite sides of said blades.

2. Apparatus for separating float from nonfloat material contained in reagentized phosphate ore slurry comprising an elongated open trough having upwardly and outwardly inclined sidewalls; means for introducing said reagentized phosphate slurry into said trough to form a shallow body within said trough; means for directing jets of water into the central portion of said trough, and passing through the depth of said slurry to provide a rebounding force within said slurry causing an initial separation of all float and a portion of nonfloat material by lifting action; a plurailty of spaced drain means near the bottom of said trough for the removal of liquid nonfloat material; quiescent zones at the sides of said trough for the dropping of additional nonfloat material; a plurality of pinched sluices in parallel along the sides of said trough arranged to receive overflow from said trough, said sluices having converging sides toward the discharge end thereof, and a downwardly sloping floor from the entry to the discharge end thereof; splitter blades disposed across the discharge end of said sluices, the end of said blades intersecting said sluices with the plane of said blades substantially parallel to said sluice floor to divide the discharge from said sluices, and compartments beneath said blades arranged so that the discharge passing on the opposite sides of said blades is separately collected.

3. Apparatus for separating and recovering phosphate ore from a liquid slurry of reagentized ore and nonreagentized gangue, including an aeration and flotation container to hold a shallow body of said slurry; means for feeding slurry into said container to form said shallow body; means for directing pressurized liquid jets at the surface of said body in said container under pressure whereby to provide air bubbles and turbulence producing a float constituent lifting current in said body; discharge means along the bottom of said container to remove nonfloat material; sluice means outwardly of said container, said sluice means declined at an angle of not more than about 8 degrees from the horizontal, and means for dividing the flow of said float material in said sluices in a plane parallel to the surface of said material.

4. Apparatus for separating phosphate ore from a slurry containing said ore along with nonphosphate granular material, said apparatus comprising an elongated shallow trough having discharge ports spaced along the bottom of said trough; slurry feeding means arranged above said trough to feed slurry into said trough and form a shallow body of slurry therein; baflie means disposed along the length of the sides of said trough in spaced parallel relation to said sides whereby to form an isolated zone along the sides of said trough, said zone being in communication with said body of slurry at the top and bottom thereof; high pressure water jets disposed above said trough between said bafiie means, the pressure provided by said jets being sufiicient to cause said jets to penetrate the body of slurry in said trough and rebound to the surface thereof, lifting reagentized ore to the surface of said body and overflowing said baffle into the said isolated zone; pinched sluices arranged in parallel along the edge of said trough to receive floatable material from said isolated zone, splitter blades disposed in a plane parallel to the floor of said sluices to divide the stream of liquid flowing in said sluices in accordance with stratification of layers in said stream.

5. A method of separating float from nonfloat material contained in reagentized phosphate ore slurry comprising the steps of introducing said slurry into a flotation zone and forming a shallow body of said slurry in said zone, subjecting said slurry in said zone to agitation and aeration to lift float materials to the surface of said slurry and provide a layer of nonfloat dense material in the bottom of said slurry, removing nonfloat material from the bottom of said slurry, guiding said float material to flow in a downwardly sloping and converging stream of increasing depth under tranquil laminar conditions, the downward slope of said stream being at an angle not substantially in excess of about 8 degrees from the horizontal whereby to provide Stratification of said stream into layers, dividing said stream into two parts in accordance with said stratification and recovering the divided parts of said stream.

6. A method for separating and recovering valuable mineral constituents from an aqueous slurry containing said constituents and gangue comprising forming a body of said slurry in an agitation and aeration zone, agitating and aerating said slurry to provide an upwardly directed lifting current suflicient to carry floatable reagentized ore but insufficient to lift a major portion of the unreagentized gangue, removing at least about 75% of said unreagentized gangue by discharging said gangue from said zone beneath the surface of said slurry, guiding 7 8 the floated reagentized ore over a quiescent zone of References Cited slurry to drop additional gangue, delivering the remaining UNITED STATES PATENTS floated material to a smooth and flat surface of a uniform declination from the horizontal not in excess 1328456 1/1920 Ross 2O9168X of about 8 degrees while simultaneously converging said 5 1912630 6/1933 Forrester 209-466 X remaining floated material into a stream of increasing 2644583 7/1953 cannon et a1 209-493 X depth to provide tranquil laminar flow, and dividing said I I stream in a plane parallel to the surface thereof into FRANK LUTTER P'lmary Examine" an upper layer containing valuable reagentized ore and HARRY B. THORNTON, Examiner.

a lower layer substantially containing Water and a small 10 L. EATHERTON Assistant Examiner. amount of nonfloat material.

Claims (1)

1. 3. APPARATUS FOR SEPARATING AND RECOVERING PHOSPHATE ORE FROM A LIQUID SLURRY OF REAGENTIZED ORE AND NONREAGENTIZED GANGUE, INCLUDING AN AERATION AND FLOTATION CONTAINER TO HOLD A SHALLOW BODY OF SAID SLURRY; MEANS FOR FEEDING SLURRY INTO SAID CONTAINER TO FORM SAID SHALLOW BODY; MEANS FOR DIRECTING PRESSURIZED LIQUID JETS AT THE SURFACE OF SAID BODY IN SAID CONTAINER UNDER PRESSURE WHEREBY TO PROVIDE AIR BUBBLES AND TURBULENCE PRODUCING A FLOAT CONSTITUENT LIFTING CURRENT IN SAID BODY; DISCHARGE MEANS ALONG THE BOTTOM OF SAID CONTAINER TO REMOVE NONFLOAT MATERIAL; SLUICE MEANS OUTWARDLY OF SAID CONTAINER, SAID SLUICE MEANS DECLINED AT AN ANGLE OF NOT MORE THAN ABOUT 8 DEGREES FROM THE HORIZONTAL, AND MEANS FOR DIVIDING THE FLOW OF SAID FLOAT MATERIAL IN SAID SLUICES IN A PLANE PARALLEL TO THE SURFACE OF SAID MATERIAL.

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