US3107215A

US3107215A - Fllotation process for concentration of pollucite ores

Info

Publication number: US3107215A
Application number: US168848A
Authority: US
Inventors: Karl C Dean
Original assignee: Individual
Current assignee: Individual
Priority date: 1962-01-25
Filing date: 1962-01-25
Publication date: 1963-10-15
Anticipated expiration: 1980-10-15

Description

3,167,215 FLOTATION PROCES FOR CONCENTRATION OF PGLLUCITE ORES Karl C. Dean, Salt Lake City, Utah, assignor to the United States of America as represented by the Secretary of the Interior N Drawing. Filed Jan. 25, 1962, Ser. Ne. 168,848 11 Claims. (61. 209-166) (Granted under Title 35, US. Code (1952), see. 266) The invention herein described and claimed may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of royalties thereon or therefor.

This invention relates to separation or concentration of cesium-containing minerals from their ores in order to facilitate recovery of cesium metal or cesium salts.

Cesium occurs chiefly as the mineral pollucite (C520 A1203 H2O GT 20320 2A1 O3 in ores which also contain a variety of other minerals such as muscovite, albite, microline, quartz, lepidolite, oligoclase and spodutmene. These ores contain other alkali metals in addition to the cesium in the pollucite. The removal of cesium from its ores is complicated by the presence of the other alkali metals, particularly rubidium, since the'problem of removing these elements from solutions obtained from solubilizing pollucite ore is costly and difiicult. Present day refining techniques by direct metal reduction require one or more distillations of the mixed alkali metals to obtain relatively pure cesium. Preliminary separation of the cesium mineral from those containing the other alkali metals would obviate the necessity for these distillations.

Other processes for recovering cesium involve production of cesium salts. Such processes require the use of expensive precipitants and ion exchange materials for separation of the cesium from other alkali metals. Their use is reduced or eliminated by concentration of the cesium mineral from a cesium ore.

Accordingly, it is an object of the present invention to provide a simple and economical method for concentrating pollucite from its ore.

A further object of this invention is to provide a simple and economical method of separation of pollucite from ores of relatively low pollucite content, thus enabling deposits of such ores to be brought into production.

It is a further object of the present invention to provide a means for separating cesium from other alkali metals present in cesium ores.

A further object of this invention is to provide a froth flotation method for the separation or concentration of pollucite from its ores.

A still further object of this invention is to provide a froth flotation process employing a particular combination of conditioning and collecting agents in order to efiect a concentration of pollucite from its ores.

Other objects and advantages will be apparent from the rest of the disclosure.

It has now been found that pollucite may be effectively separated from its ores by means of a froth flotation process in which a slurry of the pollucite ore is acidified, treated with a reagent such as hydrofluoric acid to depress the pollucite and then with a cationic reagent such as Armac CD (a coco amine acetate) which acts as a collector for the mineral constituents of the ore other than the pollucite. The Arrmac CD also has considerable frothing properties which eliminates the need for a further frother agent. The slurry is then aerated to form a froth in which the undesired minerals are collected in the froth and may be removed, the desired pollucite remaining in the aqueous phase. The process may be repeated if deite htates didiit sired to effect a still further concentration of the pollucite.

The general procedure employed in the invention is a conventional froth flotation procedure in which the ore is first ground to fine particles, water is added to form a pulp and the pulp is passed to a flotation cell where reagents are added and air is introduced.

Selective floating of the individual minerals found in a complex ore requires the use of chemical compounds or reagents which either depress or collect specific mineral particles. Depression is achieved by adding reagents that make the mineral particle hydrophilic, or water loving. Collection is achieved by rendering mineral surfaces hydrophobic or air avid. Thus, with proper grinding and the use of satisfactory reagents some of the mineral particles become air avid, attach themselves to bubbles, and float to the surface of the flotation cell and are removed. This particle product, or froth, is called a concentrate. The concentrate or froth product from a freshly ground and floated ore is called a rougher concentrate. The nonfloating or depressed mineral particles from this initial separation remaining in the test cell comprise the rougher tailing. In most laboratory flotation processes, some un desired mineral is mechanically entrapped in the froth product and this product is returned to the test cell (after removing the rougher tailing), additional water added as required, and the product refloated. The froth product of this reflotation is designated cleaner concentrate No. 1, and the non-floated product, middling No. l, or sometimes cleaner tailing No. 1. The froth may be refloated, or cleaned several additional times, either with or without added reagents. Successive froth products would be called cleaner concentrates No. 2, No. 3, No. 4, etc. The nonfloated material in the successive steps would be called either middling Nos. 1, 2, 3, 4, etc., or cleaner tailings Nos. 1, 2, 3, 4, etc. Some technologists use one term, some the other. Sometimes best results are obtained by floating the waste minerals away from the valuable mineral. This type of procedure is employed in the instant case and the waste minerals are collected as the concent-rate in the froth while the pollucite remains in the cell and is designated tailing even though it is actually a concentrate of the desired mineral. This conventional terminology has been employed in the discussion and examples which appear below.

In laboratory flotation all of the concentrate to be removed may be accomplished by the addition of all the reagents at one time, conditioning by agitation of the flotation pulp and reagents, adding air to the cell and floating the concentrate. This same objective, but usually with more selective separations, may be accomplished by partial additions of the total reagents, conditioning, and flotation in stages, rather than all at one time. These staged reagent additions, conditioning periods, and concentrate floatings are continued until inspections, or knowledge gained from previous tests, indicate suflicient material has been floated.

The process is carried out at room temperature and pressure. The raw material employed is a pollucite ore containing numerous minerals other than pollucite as described above. The exact composition of such ores will of course vary according to the deposit from which the ore is obtained. The ore is first ground (wet or dry) to a degree of fineness suflicient to liberate the cesium-bearing mineral, which may be from less than about 48 mesh to less than about mesh. The ore is then floated in its entirety or it may be first separated into two or more sized fractions. Whether flotation of the entire ore or of aseparate sized fraction is employed does not appear to materially affect the results and for economic reasons entire ore flotation is preferred. The flotation is then effected by adding water in amounts sufficient to furnish a pulp of between 20 and 45 percent solids. Sulfuric acid D is then added to adjust the pH to a value of from 1.4 to 2.7. Hydrofluoric acid is then added in an amount sufficient to aid in the selective separation of the pollucite. Though applicant does not wish to be bound by any theory as to the action of the hydrofluoric acid, it is believed that its action is that of a depressant for the pollucite. Aluminum sulfate may also be added in small quantities for control of the froth if the ore is finely ground. The slurry is then conditioned by agitation for about 10 minutes.

7 Following the conditioning step, a cationic reagent such as Armac CD is added and a further conditioning period of about 3 minutes is allowed. The slurry is then aerated to form a froth and float the non-pollucite minerals which are then removed with the froth. The pollucite mineral remains in the aqueous phase and may be recovered by filtration. The concentrate containing the waste minerais may be again treated as above to further concentrate the pollucite in the aqueous phase.

The sulfuric acid is usually added as a 10 percent by weight aqueous solution but may be used in any concentration to provide the proper pH. About 10 to 20 pounds of the 10 percent acid per ton of ore is usually required in the initial stage to provide the proper pH. Successive stages will usually require 1 to pounds to maintain the proper pH. The hydrofluoric acid is usually added as a 2.5 to 5 percent by weight aqueous solution and the total amount employed may vary from about 3.0 to 12 pounds per ton of ore. Staged additions of the hydrofluoric acid may range from about 1 to 4 pounds per ton of ore. The aluminum sulfate is usually added in the form of a percent by Weight aqueous solution. The total amount of aluminum sulfate is usually about 0.25 to 3 pounds per ton of ore, though staged additions may amount to 1 pound or less per ton of ore. The Armac CD is usually added as a 5 percent by weight aqueous solution in amounts ranging from about 0.2 to 1.5 pounds per ton of ore for each stage or a total of between 0.6 and 4.5 pounds per ton of ore for the complete roughing cycle. The amounts of reagents employed in the cleaning stages in pounds per ton of ore are as follows: Sulfuric acid- 2.0 to 5.0, aluminum sulfate-none, hydrofluoric acid 1.0 to 4.0, and Armac CDzero to 0.5. These figures would be multiplied by the total number of cleaning stages to get the total quantity of reagents for the cleaning phase. Actual concentrations of active ingredients in the aqueous reagent solutions may vary to a great extent, as from 1 to 48 percent by weight, for all reagents except the collector reagent Armac CD. The concentrations of cationic collectors such as Armac CD normally are held at between 1 and 5 percent by weight to remain within the solubility limits of the reagent and to allow better control of reagent additions. The pH range is maintained between the values of 1.4 to 2.7 to gain best over-all results. If the pH is much below the 1.4 value additional collector is required with no great increase in cesium content of tailing. If the pH is much above the 2.7 value the cesium content in the waste concentrate will be greater, thus lowering recovery.

The Armac CD is a coco amine acetate manufactured by Armour & C0. The amine portion of the Armac CD is composed of about 97 percent primary aliphatic amines of 8 to 18 carbon atoms having a mean molecular weight of 200, a molecular combining weight of 206 and an approximate melting point of 21 C. The percent composition of the primary amine content of the Armac CD is as follows: octyl, 8; decyl, 9; dodecyl, 47; tetradecyl, 18; hexadecyl, 8; octadecyl, 5; and octadecenyl, 5.

The following examples will serve to more particularly describe the invention.

EXAMPLE I apatite, 2; and tale, 1 was wet ground in an iron ball mill at 66 percent solids for five 7-minute stages to give a product 98 percent minus-IOO-mesh. An additional 1500 milliliters of Salt Lake City tap water was added to form a slurry of 33 percent solids. This slurry was then treated according to the following procedure using the proportions of ingredients given in table 1 (rougher concentrate No. l). Sulfuric acid was added to give a pH of 2.6. The hydrofluoric acid and aluminum sulfate were then added and the mixture was conditioned for a period of 10 minutes. The Armac CD was then added, followed by an additional 3 minutes conditioning period. The mixture was then aerated to form a froth causing flotation of a first rougher concentrate. Three such rougher concentrates were prepared using the reaction conditions given in Table 1. The three rougher concentrates were then removed and combined and subsequently cleaned in three stages. Each stage of the cleaning procedure consisted of return of the concentrate to the cell after the tailing had been removed. The conditions employed in each stage of the cleaning procedure are also given in Table l. The results of an analysis of the products of the separation are given in Table 1A. The head assay in Table 1A is simply an assay of the raw ore prior to treatment. The calculated head is derived from the weight and chemical analyses of the various products (concentrates and cleaner and rougher tail) to serve as a comparison with the original analyses of the head. The calculated head furnishes a check as to the accuracy of weights and assays of the test products.

The effectiveness of applicants process may be seen from the increase of the cesium to rubidium ratio of 53 to l in the calculated head to 324 to 1 in the final pollucite product comprising the combined cleaner and rougher tailings.

Table 1 FLOTATION, CONDITIONING, AND REAGENT SCHEDULE Rougher Concentrate Time, min. Reagent, lb./ton of ore Stage No. pH

Condi- Flo- H1304 HF A12(SO-l)3'18H2O Armac tioning tation CD Cleaner Concentrate Essentially the same procedure was used in this second example as in Example I, but a different ore was used, the quantities of reagents were changed, and the grind was varied. The ore represented in this example was a Southern Rhodesian pollucite ore containing the following minerals with percentages given-pollucite, 65; albite, 16; lepidolite, 13; quartz, 4; petalitc, 1; and spodumene, 1. The ore was ground in an iron ball mill for 20 minutes to give 98.7 percent of the ore minus-100-mesh in size. Flotation of this ore increased the cesium-to-rubidium ratio from 32:1 to 83:1. The fact that some of the rubidium was chemically combined with the pollucite prevented further separation by physical concentration such as flotation. The test conditions and results are shown in Tables 2 and 2A.

Table 2 FLO'IATION, CONDITIONING, AND REAGENT SCHEDULE Rougher Concentrate Time, min. Reagent, lb./ton of ore Stage No. pH

Condi- Flota, H150 HF Armac tioning tion CD 13 4 2. 6 12. 2. 0 0. 60 10 4 2. 3 4. O 1. O (i0 10 3 2. 3 3. 0 1. 0 30 Cleaner Concentrate 'Table 2A RESULTS OF FLOTATION Assay, Distribution, Weight, percent percent Products percent Cs Rb Cs Rb Combined cleaner concentrates NOS. 1, 2 25. 6 7.03 1. 84 7. 5 63. 5 Combined cleaner and rougher taiL 74. 4 29.80 36 92. 5 36. 5

Calculated head 100. 0 24. 00 74 100. 0 100. 0

EXAMPLE III This example is submitted for a Canadian pollucite ore to show that the flotation method devised is applicable to pollucite ores of greatly difierent mineral assemblages. The Canadian ore had the following percentages of mineral constituentspollcuite, 80; quartz, 7; microline, 5; albitecoligoclase, 3; spodumene, 3; amblygonite, 1; and muscovite, 1. Chemical analysis and a mineralogical examination of the flotation products jointly indicated that much of the rubidium Was combined chemically with the pollucite. The cesium-to-rubidium ratio was not changed radically by flotation, but this test does show that quartz, microcline, and spodumene may be separated from pollucite by this invention. Conditions and results are given in Tables 3 and 3A.

Hydrochloric or phosphoric acids may be used in place of sulfuric acid for pH regulation; however, cost will normally rule out the possibility of substituting these acids.

Various cationic collectors may be used in place of the Armac CD. These cationic reagents may be, for example, fatty amines, fatty amine acetates or quaternary ammonium salts. These reagents are sold under the following trade names: Armeens, Armacs, Arquads and Ethomeens, all from Armour Chemical Division as well as numerous other trade names for similar materials from other manufacturers.

The conditioning time, during which the reagents and pulp are intimately mixed, may also be varied to obtain optimum results. The acid conditioning period is usually about ten minutes but may range from about 4 to 10 minutes. The second or collector conditioning time is usually about 3 rninutes. The values of conditioning time given in the tables is the total conditioning time in which a 3 minute period was employed for the collector conditioning.

Ambient temperature and pressure are usually satisfactory. Little difliculty with temperature change should be expected if normal seasonal fluctuations are the extremes.

Ordinary city tap water containing an average of 66, 15 and 300 per million of calcium, magnesium and total dry solids, respectively, was used in all the tests. No difficulties should be encountered with most available culinary waters though, of course, distilled or deionized water could also be used. Water is generally used in forming the pulp since other liquids such as organic liquids are usually eliminated from consideration because of cost and interaction with the flotation reagents.

The laboratory flotation cells used in these tests were of the Galigher and Fagergren types. The Galigher type consists of a container with a centrally located impeller for inducing agitation within the pulp. This cell does not aerate the pulp by mechanical action but is supplied with low pressure air, controlled by the flotation experimenter, from a suitable compressor. The Fagergren cell also has a centrally located impeller for agitation which is enclosed by a standpipe containing a valve for air control. Air is drawn through the standpipe when needed by action of the swiftly moving impeller. The air valve is closed during periods of agitation conditioning and opened to admit air when flotation is desired.

The process as described is a discontinuous process as all laboratory batch cell type operations must be. However, the methods developed by using laboratory cells are, if properly conducted, fully convertible to use in continuous many celled operations. In continuous operation the concentrate would be removed from successive flotation cells with conditioning cells used between flotation cells to obtain proper contact between the reagents and the mineral particles by agitation conditioning.

Recovery of the concentrate is effected by collecting it in pans as it is scraped from the flotation cell and subsequently filtered. After all the concentrates are floated the product remaining in the cell also is filtered to remove the bulk of the water. The concentrates and tailings may be dried after filtration if such a product is desired. In continuous operation the concentrates and tailings are 7 discharged into separate launders (troughs) which discharge into thickeners. The thickened products then are fed into filters where the majority of the Water is removed. Drying may follow if desired.

It will be appreciated from a study of the foregoing specifications that the invention described herein is capable of various modifications and changes without departing firom its essential spirit and scope.

What is claimed is:

1. A process for the concentration of a cesium mineral from an ore containing the same together with undesired minerals which comprises: adding to an aqueous pulp of said ore in a flotation cell (1) an acid in amount suflicient to adjust the pH to about 1.4 to 2.7; (2) a depressant for the cesium mineral comprising hydrofluoric acid; (3) a collector for the undesired minerals comprising a cationic reagent and then froth floating the undesired minerals from the cesium mineral.

2. The process of claim 1 in which aluminum sulfate is also added to the pulp in order to control the froth.

3. The process of claim 1 in which the cesium mineral is pollucite.

4. The process of claim 1 in which the acid is sulfuric acid.

5. The process of claim 1 in which the cationic reagent is a coco amine acetate.

6. A process for the concentration of a cesium mineral from an ore containing the same together with undesired minerals which comprises: adding to an aqueous pulp of said ore (1) an acid in an amount sufficient to adjust the pH to a value from about 1.4 to 2.7 and (2) a depressant for the cesium mineral comprising hydrofluoric acid, concles of undesired mineral and then froth floating the undesired minerals from the cesium mineral.

7. The process of claim 6 in which the initial conditioning period is 10 minutes and the second conditioning period is 3 minutes.

8. The process of claim 6 in which the depressant is added in an amount of from 3.0 to 12.0 pounds per ton of ore.

9. The process of claim 6 in which the collecting agent is added in an amount of from 0.6 to 4.5 pounds per'ton of ore.

10. A process for the concentration of acesium mineral from an ore containing the same together with undesired minerals which comprises: adding to an aqueous pulp of said ore in a flotation cell (1) an acid in an amount sufficient to adjust the pH to a value of about 1.4 to 2.7; (2) a depressant for the cesium mineral comprising hydrofluoric acid; and (3) a collector for the undesired minerals comprising a cationic reagent, aerating the pulp in order to froth float a concentrate containing the undesired minerals and leave the cesium mineral as the tailing in the aqueous phase and separating the concentrate and tailing from the cell.

11. The process of claim 10 in which the concentrate containing the undesired minerals and entrapped cesium mineral is returned to the flotation cell and refloated in order to further remove the cesium mineral from the undesired minerals in the concentrate.

References Cited in the file of this patent t UNITED STATES PATENTS OMeara Oct. 6, 1942 Browning et a1 Apr. 3, 1962 OTHER REFERENCES Taggart: (Handbook of Mineral Dressing), March 1956 (sec. 12-26).

Claims

1. A PROCESS FOR THE CONCENTRATION OF A CESIUM MINERAL FROM AN ORE CONTAINING THE SAME TOGETHER WITH UNDESIRED MINERALS WHICH COMPRISES: ADDING TO AN AQUEOUS PULP OF SAID ORE IN A FLOTATION CELL (1) AN ACID IN AMOUNT SUFFICIENT TO ADJUST THE PH TO ABOUT 1.4 TO 2.7; (2) A DEPRESSANT FOR THE CESIUM MINERAL COMPRISING HYDROFLUORIC ACID; (3) A COLLECTOR FOR THE UNDESIRED MINERALS COMPRISING A CATIONIC REAGENT AND THEN FROTH FLOATING THE UNDESIRED MINERALS FROM THE CESIUM MINERAL.