US2984348A - Beneficiation of potash ores - Google Patents

Description

May 16, 1961 A. ADAMS ETAL BENEFICIATION oF PoTAsH oREs Filed Aug. 14, 195s Patented May 16, 1961 BENEFHCIATION F PO'IASH DRES Albert Adams and William B. Dancy, Carlsbad, N. Mex.,

assignors to International Minerals d; Chemical Corporation, a corporation of New York Filed Aug. 14, 1958, Ser. No. 755,111

12 Claims. (Cl. 209-12) The present invention generally relates to the benelication of potash ores. More particularly, it relates to an improved process for the separation of sylvite from ores of the sylvinite type, for example such ores as are mined in the Carlsbad district of New Mexico.

As is well known, potash is of great economic importance. Extensive deposits of potash salts are found on every continent. However, in practically no instance is the potash salt found in a substantially pure form. On the North American continent, one frequently encountered potash salt is sylvite (KCl). The KCl is not often found in any appreciable quantities as pure sylvite ore but is most often found as sylvinite ore, which is a mixture of sylvinite and halitc (NaCl). A typical analysis of a sylvinite ore is as follows:

Other constituents or impurities consisting of silicates,

sulfates, etc. 4

This invention is of particular value in connection with processes of the general type disclosed in the Tartaron, Cole and Duke Patent No. 2,288,497. Said patent describes a process which comprises suspending comminuted sylvinite ore in a circulating saturated brine formed by dissolving the soluble constituents of the ore in water and then floating the particles of sylvite by means of a suitable collector agent While permitting the particles of halite to settle. The type of process to which this invention relates is thus distinguished from that type of process disclosed in the Weinig Patent No. 2,222,331, issued November 19, 1940, in which the halite is floated and the sylvite is settled.

In processes of this general character, it has been the general practice to grind the ore to a rather line mesh, for example, to a degree of neness Where at least 90% of the ore would pass through a sieve of about 40 mesh. Flotation of the valuable sylvite constituents of an ore of such degree of lineness is not too dillicult a problem, and various types of collector agents for effecting such flotation can be used. It is, however, very costly to thoroughly size an ore so that substantially all of the ore particles to the flotation process fall within a small size range. Furthermore, the expense of fine grinding is rather considerable and adds materially to the cost of the final product.

ln general, it may be stated that the llotation of ore consisting of relatively large particles is attended with considerably more diiliculty than when the particles are of relatively smaller dimensions. In other words, it is generally more diflicult to iloat relatively large size sylvite particles than it is to iloat relatively smaller particles. It has also been observed that the large sylvite particles make up a substantial amount of the sylvite which is not floated and which is, therefore, usually lost in the tailings.

In a dotation operation, the ore is slurried in a liquid to prepare a pulp of the ore. In a sylvite flotation process, the potash ore is slurried in a saturated brine solut1on to produce a brine slurry or pulp of from about 50% to about solids. The pulp is then reagentized with a suitable collector, diluted with brine, and passed to .a flotation cell. In the flotation cell the pulp is kept 1n circulation and is contacted with air. Air bubbles adhere to the reagentized sylvite particles and float the sylvite particles. The sylvite float is raked ofi of the top of the flotation cell. Not all of the sylvite is floated oli' in the first flotation cell and the remaining pulp is removed as underflow from the first cell and is passed to a second ilotation cell. In the second cell, the flotation operation is repeated, a sylvite concentrate is oated olf, and the remaining pulp may be passed to a third ilotation operation. A flotation machine usually contains a plurality of such cells associated together in series. After a series of flotation operations, the remaining pulp, from which substantial amounts of sylvite have been removed, is discarded as a tailing. This initial flotation operation is denominated a rougher flotation, the lloat product is denominated a rougher float or rougher concentrate, and the tailing is denominated a rougher tail.

The rougher concentrate, while containing substantially all of the sylvite values in the charged pulp, also contains a substantial amount of fine halite particles which were removed with the sylvite. Therefore, it is conventional practice to combine the rougher concentrate from the individual otation cells and subject the combined rougher concentrates to a cleaner flotation operation. In the cleaner flotation operation, the rougher concentrate in a pulp is subjected to flotation in a plurality of flotation cells in series. The uniloated pulp recovered from the last of the cleaner flotation cells is denominated a mid or a middling and is usually recycled to the rougher cells. The float product from the cleaner operation is recovered as a high grade sylvite product, usually denominated a cleaner concentrate.

Since it is more difficult to float the larger sylvite particles as compared with the smaller sylvite particles, in an operation as above described, considerable amounts of sylvite are lost as large sylvite particles in the rougher tailings. This loss, of course, tends to decrease the eiliciency of the flotation operation and it is with the problem of increasing the efficiency that the present invention is concerned.

It is accordingly an object of the present invention to provide an improved process for the recovery of sylvite from potash ores.

It is another object of the present invention to provide an improved flotation process for the recovery of sylvite from sylvinite ores.

It is a further object of the invention to provide an improved process for the recovery of sylvite from sylvinite ores, which process includes a llotation operation and a sizing step.

These and other objects of the present invention will be apparent to those skilled in the art as the description of the present invention progresses.

In accordance with the present invention, it has been discovered that eminently satisfactory beneiiciation of potash ores and minerals can be achieved by means of a series of critical and interdependent process steps. Generally described, the present invention is a process for beneiciating a potash ore which comprises slurrying a potash ore containing sylvite with brine saturated at least with respect to sylvite, reagentizing the slurried ore with a reagent having a preferential affinity for the sylvite, subjecting the reagentized slurry to a first flotation operation in a plurality of rougher flotation cells connected in series, subjecting the flotation concentrate from at least the rst of the series of rougher ilotation cells to a second flotation operation, separately recovering the fioat product of said second flotation operation and the non-float product of said second dotation operation, subjecting the flotation concentrate from at least the last cells of the series of rougher dotation cells and at least a portion of the non-float product of said second iiotation operation to a sizing operation, and separately recovering a line fraction and a coarse fraction from the hydroconing operation. The coarse fraction is a sylvite material of high purity and may be recovered as a product or" the process.

In this novel process, potash ore containing sylvite, for example, sylvinite ore as received from the mine, is comminuted to economical liberation size to produce a granular feed material. The comminution of the ore to the liberation ofthe various constituents is effected to liberate a substantial amount of the various constituents. it may be desirable and economical to comminute the ore to liberate substantially all of the constituents; however, the ore may be liberated to a lesser extent, for example, to 7080% liberation. This granular material is preferably sized to produce a granular feed of a particle size in the range of about -8 mesh. The comminution may be carried out dry or in a saturated brine and in any suitable comminuting apparatus such as a ball mill, rod mill, roller mill, hammer mill, or any other suitable type of grinding or crushing apparatus. When the ore is ground to the mesh size indicated, the sylvite values, halite values, and gangue values are substantially liberated from each other and the ore is ready for further treatment in accordance With this invention.

The ore While in a state of subdivision sufficient to substantially completely liberate the desired components from the gangue is slurried in a brine solution which is substantially saturated with respect to sylvite and also substantially saturated with respect to halite. The saturated brine is slurried with the comminuted ore to form a slurry of from about 50% to about 75% solids, and reagents are introduced into the slurry and dispersed by agitation. The reagents used are cationic agents and are added to selectively float the sylvite particles from the halite particles. Useful reagents are the collector agents selected from the class of primary aliphatic amines of about C-ldr to C-2O length carbon chains and their acid addition salts, preferably the `acetate or hydrochlorides, for example, octadecyclamine acetate, hexadecylamine hydrochloride, and the like, of varying degrees of unsaturation depending upon the temperature of the brine in which the flotation operation is carried out. The amine reagents float potassium chloride.

After introducing the reagents having a preferential ainity for the sylvite constituents of the mixture, the slurry is diluted, preferably to a solids concentration between about and about 35% solids, and the diluted slurry is passed to a rougher flotation cell. In the rougher flotation cell, in the presence of mechanical agitation and/or aeration, a froth is formed which carries the sylvite to the surface Where the froth and its suspended solids are removed by overiiow from thev dotation cell. The removal of the iloated solids as overflow from the cell is usually promoted by the use of paddles or rakes which skim over the surface of the brine in the cell and move the oat off.

The iiotation operation is carried out in a plurality of such ilotation cells associated together in series. Thus, in the first flotation cell, a large portion of the sylvite may be iloated out while still leaving in the pulp a substantial amount of sylvite, and this is substantially removed by a repetition of the floation process in the succeeding cells to the end that the pulp passing from the nal cell contains substantially none of the sylvite particles. Flotation machines having a plurality of ota-tion cells connected in series are commercially available and preferred machines are those referred to in the art as Fagergren flotation machines and Denver flotation 4 machines. have five cells connected in series.

As hereinbefore set forth, it has been noted that the larger sylvite particles are more ditiicult to float as compared to smaller sylvite particles. Therefore, some larger size sylvite particles tend to remain in the latter of the flotation cells in series. ln accordance with the present invention, the float products from this initial rougher flotation are separately collected in two float portions. Each float portion includes the float from one flota-tion cell or from a plurality of such cells in series. The first float portion which is separately collected includes at least the oat product from the iirst cell of the series of cells and the second float portion which is separately collected includes at least the float product from the last cell of the series of cells. Further, in accordance with the present invention, the latter of the cells of the series, including the last cell, are preferably operated so -that heavily overflowing conditions are maintained so as to float oif larger sylvite particles.

The first float portion separately recovered from the rougher flotation operation contains sylvite and some halite. To upgrade this first float portion, it is passed to a cleaner flotation operation. The rst float portion is of high solids content and, therefore, it is preferred to slurry it with saturated brine so as to obtain a slurry having a solids concentration of from about 20% to 35% solids. The rst float portion usually has suiicient cationic reagent present so that additional cationic reagent is not necessary in the cleaner flotation; however, if desired, ybefore diluting the first float portion, it may be conditioned with additional cationic reagent. The cleaner operation, like the rougher flotation operation, is usually performed in a series of flotation cells. The cleaner oat is a product of high sylvite content and is usually recovered as a nal product of the process. However, since the larger sylvite particles are more difficult to float, some of the larger sylvite particles are not floated in the cleaner operation. Following the steps of the present invention, however, the losses formerly encountered by the difficulty in floating these larger sylvite particles are substantially reduced.

In accordance with the present invention at least a portion of the non-oated portion from the cleaner flotation operation, usually denomina-ted mids or middlings, is combined with at least a portion of the second float portion collected from the rougher flotation operation and the combined stream is subjected to a sizing or Wet classication treatment. The combined stream contains substantial amounts of larger sylvite and ne halite particles. The sizing or wet classification or hydroclassication substantially separates the larger sylvite particles from the line halite particles. The sizing or hydroclassiiication may be performed in any suitable manner such as by the use of rake classifiers, screens, etc.; however, the sizing is preferably performed in a hydroconing operation using at least one hydrocone. In a hydrocone a separation is made in the cone-shaped part of the hydrocone by the action of centrifugal and centripetal forces. The heavier material, which contains the major portion of the larger sylvite particles, leaves the cone as underflow. The lighter material, which contains the major portion of the tine halite particles, leaves the cone as overflow.

The underflow from the hydrocone is predominantly coarse sylvite. However, it usually still contains sorne tine halite. The ne halite may be further removed by a further sizing operation which preferably is a screening operation. The coarser fraction from the screening operation is substantially pure coarse sylvite. This coarse sylvite is preferably dewatered and dried and the dried material may be recovered as a product of the process.

In a preferred operation, at least a portion of the tine size fraction or cyclone overliow is recycled to the The Fagergren flotation machines usually Y rougher flotation operation. It is also preferred that at least a portion of the tine material which passed through the screen in the screening operation be recycled to the rougher llatation operation. The recycling feature makes maximum use of the saturated brine and increases recovery of sylvite.

Having generally described the process of the invention, a more specific and detailed description will be given with reference to the accompanying drawing which is a diagrammatic flow sheet illustrating the general application of the process of the invention.

Referring to the drawing, a reagentized sylvinite flotation feed or pulp is introduced through line 7 into a first ilotation cell 9 of a series of rougher flotation cells. The fresh feed in line 7 is combined with a recycle stream being recycled through line 11. The production of the recycle stream 11 will be hereinafter set forth. The fresh feed is prepared for ilotation by first comminuting and screening a potash ore to obtain a -8 mesh fraction, desliming the comminuted ore, and conditioning the deslimed ore in saturated brine at 60% solids content for two minutes with about 1.0 pound of potato starch and 0.15 pound of aliphatic amine per ton of feed. The conditioned ore is then diluted to 25 solids with saturated brine and the pulp is passed through line 7 into the first flotation cell 9. A lloat fraction is Withdrawn from the llotation cell 9 through line 13 and the remaining non-floated pulp is withdrawn through line 15 and passed to the second llotation cell 17. In the second llotation cell additional float product is withdrawn through line 19. The noniloated pulp is withdrawn from cell 17 through line 21 and is passed to the third flotation cell 23. In the third flotation cell additional float fraction is produced and is Withdrawn through line 25. The noniloated pulp is withdrawn from cell 23 through line 27 and is passed to a fourth flotation cell 29.

The lloat fractions in lines 13, 19 and 25 are combined in line 31 and the combined iloat fractions are diluted fwith brine entering through line 33 to produce a flotation feed containing 25% solids. The diluted combined float fractions are introduced through line 35 to a cleaner llotation operation in a series of cleaner llotation cells 37, 39, 41, 43 and 45. The lloat products from each of these cleaner cells are recovered and combined in line 47. The lloat product from the cleaner cells is of high purity and may be recovered as a sylvite product of the process. The non-floated fraction removed from the last of the cleaner cells 45, through line 49 contains substantial amounts of line halite as well as substantial amounts of larger size sylvite and is further processed as is hereinafter set forth to recover the sylvite.

Referring back to the rougher llotation operation and specifically the flotation in the fourth rougher cell 29, the ilotation operation in this cell 29 is conducted with a heavy overflow so as to facilitate the recovery of substantial amounts of the larger sylvite particles. The lloat fraction is Withdrawn from cell 29 through line 51. The non-floated pulp is Withdrawn from cell 29 through line 53 and is passed to the fifth and last rougher flotation cell 55. This last rougher cell is also operated with a heavy overflow so as to float substantial amounts of the larger sylvite particles. The remaining non-floated pulp is Withdrawn from the last rougher cell 55 through line 57 and may be discarded as a. waste tailing. The floated fraction is withdrawn from the last cell through line 59 and is combined with the float fraction from the fourth rougher cell 29 in line 61. The combined rougher float fractions, 51 and 59, in line 61 are also combined with the non-lloat fraction 49 of the last cleaner flotation cell and the combined fractions in line 63 are passed into a hydrocone 65 for a hydroconing operation. The hydrocone 65 is a closed top cyclone. The feed material in line 63 is fed tangentially into the hydrocone. The lighter portion of the feed introduced via line 63, which consists of line halite particles, leaves the cone65' as overllow through line 67 and is recycled to the rougher llotation operation through lines 67 and 11l.

The heavier portion of the feed material introduced via line 63, which consists of larger or coarse sylvite particles, leaves the cone 65 as underllow through line l69. The material in line 69 is screened in screening zone 71 to further separate the sylvite from the fine halite particles. A screening on about 24 mesh has proven satisfactory. The fine material passing through the screen 71 is withdrawn through line 73 and is combined with the hydrocone overllow in line 67 and the combined streams in line 11 are reintroduced to the rougher flotation operation as above described.

The coarse material retained on the screen 71 is withdrawn through line 75 and is dewatered and dried in zone 77. A coarse sylvite product is withdrawn from dewatering and drying zone 77 through line 79.

In the foregoing description ve flotation cells were used in the rougher and cleaner operation; however, this was only for purposes of illustration and it is to be understood that any suitable plurality can be used in each of the llotation operations.

In a commercial embodiment of the present invention, an increase in sylvite production of 2% was obtained by using this process as compared to a conventional otation process using only a rougher and cleaner flotation operation.

The following example is given to illustrate a specic application of the instant novel process and is not to be construed as limiting the invention thereto.

Example A sylvinite feed material has the following size and mineral analysis:

The sylvanite feed material was slurred with a saturated brine solution to 60% solids. The slurried material Was then conditioned for two minutes with one pound of potato starch and 0.15 pound of aliphatic amine hydrochloride per ton of feed. The aliphatic amine used is sold by Armour & Company under the trade name Armeen and was neutralized with hydrochloric acid. The conditioned ore was then diluted to 25 solids with saturated brine.

The diluted material was then subjected to a flotation operation at the rate of 4200i g.p.m. in a standard flotation machine which has five cells connected in series. The float sylvite products from the first three cells were separately recovered and combined. This combined material had the ilollowing size and mineral analysis:

The lloat products from the last two cells were separately recovered and combined. This combined material had the following size and mineral analysis:

Mesh Size Weight Percent Total Mineral Percent KZO Analysis 28.0 60.3 Sylvite, 50%. 39. 59.0 Halite, 50%. 16. 0 45. 0 17.0 8.0

The combined float product from the first three rougher cells was diluted with saturated brine to 20% solids and was then subjected to a standard cleaner flotation operation at the rate of 1300 gpm. in a -Fagergren flotation machine which has three cells in series. The Sylvite float product recovered from the cleaner operation had the following analysis:

Percent Sylvite 97 Halite 3 The middling recovered from the cleaning dotation operation had the following analysis:

Percent Sylvite 80 Halite 20 Mesh size-analysis: Percent l-l-IO 3 -}14 14 14 i}20 62 2l Mineral analysis: Percent KCl 97 NACl 3 The overall recovery of sylvite from the sylvinite feed was 88%.

The description of the invention utilized specific reference to certain process details; however, it is to be understood that such details are illustrative only and not by way of limitation. Other modifications and equivalents of the invention will be apparent to those skilled in the art from the foregoing description.

Having nofw fully described and illustrated the invention, what is desired to be secured and claimed by Letters Patent is set forth in the appended claims.

We claim:

1. A process for the recovery of Sylvite from potash ores containing Sylvite which comp-rises slurrying a potash ore containing sylvite ywith brine saturated at least with respect to Sylvite, reagentizing the slurried ore with a reagent having a preferential affinity for the Sylvite, subjecting the reagentized slurry to a first liotation operation in a plurality of rougher cells connected in series, subjecting the flotation concentrate from at least the `first of the series of rougher fiotation cells to a second :dotation operation, separately recovering the float product of said second flotation operation and the non-float product of said second iiotation operation, subjecting the flotation concentrate from at least the last of the series of rougher flotation cells while employing a greater overflow volume of brine than employed in at least the first of said series of rougher flotation cells and at least a portion of the non-float product of said second flotation operation to a sizing operation, and separately recovering a small size fraction and a larger size fraction from the sizing operation.

2. A process for the recovery of Sylvite from a potash ore containing Sylvite which comprises slurrying a potash ore containing sylvite, while in a state of subdivision sufiicient to substantially completely liberate the Sylvite from the other components of the ore with brine saturated at least with respect to sylvite, reagentizing the slurried ore with a reagent having a preferential affinity for the sylvite, subjecting the reagentized slurry to a first flotation operation in a plurality of rougher flotation cells connected in series, recovering the float products from said first liotation operation in at least two separate portions, one lioat portion including the iioat product from at least the first of the series of rougher flotation cells and the second portion including the fioat product from at least the last of the series of rougher otation cells while employing a greater overflow volume of brine than employed in at least the first of said series of rougher flotation cells, subjecting said first portion to a second flotation operation, separately recovering the fioat product of said second fiotation operation and the non-float product of said second flotation operation, subjecting the second float portion from said first flotation operation and at least a portion of the non-float product of said second flotation operation to a sizing operation, and separately recovering a small size fraction and a larger size fraction from the sizing operation.

3. A process for the recovery of sylvite from potash `ores containing Sylvite which comprises slurrying a potash ore containing sylvite with brine saturated at least with respect to sylvite, reagentizing the slurried ore with a reagent having a preferential afiinity for the Sylvite, subjecting the reagentized slurry to a first flotation operation in a plurality of rougher cells connected in series, subjecting the flotation concentrate from at least the first of the series of rougher flotation cells to a second flotation operation, separately recovering the fioat product of said second fiotation operation, subjecting the flotation concentrate from at least the last of the series of rougher otation cells while employing a greater overflow volume of brine than employed in at least the first of said series of rougher flotation cells and at least a portion of the non-float product of said second iiotation operation to a hydroconing operation, and separately recovering as overflow from said hydroconing operation a fine fraction and as underfiow from said hydroconing operation a coarse fraction of Sylvite which is removed from the process as a finished concentrate, and recycling at least a portion of said fine fraction to said `first otation operation.

4. A process for the recovery of sylvite from sylvinite ore which comprises slurrying a potash ore containing sylvite, while in a state of subdivision sufiicient to substantially completely liberate the sylvite from the other components of the ore with brine saturated at least with respect to Sylvite, reagentizing the slurried ore with a reagent having a preferential aiiinity for the sylvite, subjecting the reagentized slurry to a first fiotation operation in a plurality of rougher flotation cells connected in series, recovering the float products from said first flotation operation in at least two separate portions, one float portion including the float product from at least the first of the series of rougher flotation cells and the second portion including the oat product from at least the last of the series of rougher iiotation cells while employing a greater overfiow volume of brine than employed in at least the first of said series of rougher flotation cells, subjecting said first portion to a second flotation operation, separately recovering the float product of said second otation operation and the nou-float product of said second ilotation operation, subjecting the second float portion from said first ilotation operation and at least a portion of the nonoat product of said second flota-tion operation to a classication operation, and separately rccovering a small size fraction and a larger size fraction from the classification operation, and recycling at leas-t a portion of said small size fraction to said first flotation operation.

5. A process for the recovery of sylvite from sylvinite ore which comprises slurrying a potash ore containing sylvite, while in a state of subdivision sufficient to substantially completely liberate the sylvite from the other components of the ore with brine saturated at least with respect to sylvite, reagentizing the slurried ore with a reagent having a preferential ainity for the sylvite, subjecting the reagentized slurry to a rst tlotation operation and a plurality of rougher otation cells connected in series, recovering the oat products from said rst dictation operation in at least two separate portions, one iloat portion including the iioat product from at least the first of the series of rougher flotation cells and the second portion including the float product from at least the last of the series of rougher otation cells While employing a greater overflow volume of brine than employed in at least the iirst of said series of rougher notation cells, subjecting said rst portion to a second ilotation operation, separately recovering the iloat product of said second dotation operation and the non-oat product of said second otation operation, subjecting the second float portion from said rst otation operation and at least a portion of the non-float product of said second otation operation to a hydroconing operation, recycling at least a portion of the overflow from said hydroconing operation to said iirst notation operation, screening at least a portion of the underflow from said hydroconing operation and recycling at least a portion of the screening underilow to said first dotation operation.

6. The process of claim wherein said screening operation is on about 24 mesh.

7. A process for the recovery of sylvite from potash ores containing sylvite and halite which comprise slurry ing such an ore with brine saturated at least with respect to sylvite, reagentizing said slurried ore with a reagent having preferential anity for the sylvite, subjecting said reagentizing slurry to a flotation operation :in a plurality of rougher cells, connected in series, separately collecting an initial rougher flotation concentrate from at least the rst of the series of rougher cells and a second rougher otation concentrate from at least the last of the series of rougher otation cells while overflowing a greater amount of brine from these cells than is overilowed from at least the rst of the series of rougher -flotation cells, and sizing the second rougher otation concentrate into a sylvite fraction of large particle size and a halite fraction of small particle size.

8. A process as in claim 7 wherein the second rougher otation concentrate is screened to separate sylvite from halite.

9. A process as in claim 7 wherein the second rougher flotation concentrate is subjected to a hydroconing operation to recover a sylvite fraction of large particle size and a halite fraction of small particle size.

10. A process as in claim 7 wherein the initial rougher `flotation concentrate is subjected to a cleaner otation operation in a plurality of cleaner flotation cells connected in series, the underflow middlings being sized into a small size fraction and a large size fraction, at least a portion of said small size fraction being reintroduced into the said rougher ilotation operation and the overow cleaner sylvite concentrate being processed to recover sylvite.

1l. A process as in claim 10 wherein the second rougher flotation concentrate is screened to separate sylvite from halite.

12. A process as in claim 10 wherein the second rougher flotation concentrate is subjected to a hydroconing operation to recover a sylvite fraction of large particle size and a halite fraction of small particle size.

Fontein May 22, 1956 Bourne et al. Aug. 26, 1958

Claims (1)

1. 4. A PROCESS FOR THE RECOVERY OF SYLVITE FROM SYLVINITE ORE WHICH COMPRISES SLURRYING A POTASH ORE CONTAINING SYLVITE, WHILE IN A STATE OF SUBDIVISION SUFFICIENT TO SUBSTANTIALLY COMPLETELY LIBERATE THE SYLVITE FROM THE OTHER COMPONENTS OF THE ORE WITH BRINE SATURATED AT LEAST WITH RESPECT TO SYLVITE, REAGENTIZING THE SLURRIED ORE WITH A REAGENT HAVING A PREFERENTIAL AFFINITY FOR THE SYLVITE, SUBJECTING THE REAGENTIZED SLURRY TO A FIRST FLOTATION OPERATION IN A PLURALITY OF ROUGHER FLOATATION CELLS CONNECTED IN SERIES, RECOVERING THE FLOAT PRODUCTS FROM SAID FIRST FLOTATION OPERATION IN AT LEAST TWO SEPARATE PORTIONS, ONE FLOAT PORTION INCLUDING THE FLOAT PRODUCT FROM AT LEAST THE FIRST OF THE SERIES OF ROUGHER FLOTATION CELLS AND THE SECOND PORTION INCLUDING THE FLOAT PRODUCT FROM AT LEAST THE LAST OF THE SERIES OF ROUGHER FLOTATION CELLS WHILE EMPLOYING A GREATER OVERFLOW VOLUME OF BRINE THAN EMPOLYED IN AT LEAST THE FIRST OF SAID SERIES OF ROUGHER FLOTATION CELLS, SUBJECTING SAID FIRST PORTION TO A SECOND FLOTATION OPERATION, SEPARATELY RECOVERING THE FLOAT PRODUCT OF SAID SECOND FLOTATION OPERATION AND THE NON-FLOAT PRODUCT OF SAID SECOND FLOTATION OPERATION, SUBJECTING THE SECOND FLOAT PORTION FROM SAID FIRST FLOTATION OPERATION AND AT LEAST A PORTION OF THE NON-FLOAT PRODUCT OF SAID SECOND FLOTATION OPERATION TO A CLASSIFICATION OPERATION, AND SEPARATELY RECOVERING A SMALL SIZE FRACTION AND A LARGER SIZE FRACTION FROM THE CLASSIFICATION OPERATION, AND RECYCLING AT LEAST A PORTION OF SAID SMALL SIZE FRACTION TO SAID FIRST FLOTATION OPERATION.

Images