US3295767A

US3295767A - Non-metallic flotation process

Info

Publication number: US3295767A
Application number: US308355A
Authority: US
Inventors: Charles W Becker; Roland S Foster
Original assignee: Dow Chemical Co
Current assignee: Dow Chemical Co
Priority date: 1963-09-12
Filing date: 1963-09-12
Publication date: 1967-01-03
Anticipated expiration: 1984-01-03

Description

United States Patent Ofifice 3,295,767 NON-METALLIC FLOTATION PROCESS Charles W. Becker, Angleton, Tex., and Roland S. Foster,

Arvada, Clo., assignors to The Dow Chemical Company, Midland, Mich, a corporation of Delaware No Drawing. Filed Sept. 12, 1963, Ser. No. 308,355 6 Claims. (Cl. 241-49) The invention is an improvement in the art of flotation.

Flotation is a process of treating a mixture of finely divided mineral solids, e.g., a pulverulent ore, suspended in a liquid whereby a portion of such solids having certain characteristics are separated from other finely divided mineral solids having at least some dififerent characteristics by introducing a gas (or providing a gas in situ) in the liquid, to produce a frothy mass containing solids having certain characteristics, on the top of the liquid, and leaving suspended (unfrothed) solids having other characteristics. Flotation is based on the principle that introducing a gas into a liquid containing solid particles of diflerent materials suspended therein causes adherence of some gas to certain suspended solids and not to others and makes the particles having the gas thus adhered thereto lighter than the liquid. Accordingly, they rise to the top of the liquid to form a froth. Earlier US. patents which are more-or-less basic in this area are: 735,071 issued in 1903; 776,145 in 1904; 835,120 in 1906; 862,678 in 1909; and 1,104,755 in 1914.

A number of progressive improvements have been the subject of subsequent patents in the field wherein various solids have been admixed with the suspension to improve the frothing process. Such added solids are classed according to the function to be performed: collectors, e.g., high carbon chain carboxylic acids and potassium and sodium salts thereof; frothers which impart the property of forming a stable froth, e.g., natural oils such as pine oil and eucalyptus oil; activators to induct flotation in the presence of a collector, e.g., copper sulfate or sodium phosphate; depressants, e.g., sodium carbonate, which tend to prevent a collector from functioning as such on a mineral which it is desired to retain in the liquid, and thereby discourage a substance from being carried up and form-- ing a part of the froth.

It is of importance to bear in mind that additaments of the above type are selected for use according to the nature of the ore, the mineral sought to be recovered, and the other additaments which are to be used in combination therewith.

An understanding of the phenomena which make flotation a particularly valuable industrial operation is not essential to the practice of the invention. They appear, however, to be largely associated with selective affinity of the surface of particulated solids, suspended in a liquid containing entrapped gas, for the liquid on one hand and the gas on the other.

The flotation principle is applied in a number of mineral separation processes, among which is the separation of such minerals as beryllium from such other metallic minerals as fluorspar (also known as fluorite) which is largely CaF from the beryllium ore, one of which is bertrandite. Beryllium has many uses, a large number of which have relatively recently expanded, e.g., as an alloying metal with copper, nickel, or aluminum, in X-ray window and fluorescent lamp coatings, and in electronic devices. Fluorspar is among the principal sources of fluo- Fatented Jan. 3, 1967 rine. Although fluorine in the combined state is a relatively abundant element, its occurrences in a percent by weight of its source materials is usually insuflicient to warrant commercial operations which require quarrying or mining, refinement, and beneficiation. New uses for fluorspar and for fluorine obtained therefrom are being discovered and consequently better ways of recovering the fluorine-containing mineral are being sought. Calcite, i.e., CaCO is present in bertrandite and heretofore has presented a problem of contamination.

It is known to separate fiuorspar from other minerals associated therewith by the flotation procedure wherein the fluorspar is removed in the froth. In carrying out the flotation procedure, it is known to acid such material as tannic acid or tannin to depress calcite and to add a carboxylic acid as a collector. Heretofore, calcite has remained in the tails or unfrothed portion during flotation and, therefore, has persisted as a contaminant of the beryllium values subsequently recovered from the tails. Known ways of subsequently separating the calcite from the beryllium have not been satisfactory.

A need exists for an improved method of separating beryllium values from other components of bertrandite ore and particularly for separating the beryllium from both fluorspar and calcite there present by the application of the flotation principle.

The principal object of the invention is to meet this need by providing an improvement in the flotation process which is useful in separating beryllium values from fluorspar and calcite in bertrandite ore. How this and related objects are attained will be made clear in the ensuing description and is succinctly defined in the appended claims.

We have discovered that beryllium values can be separated from both calcite and fluorspar, employing the flotation principle, by admixing sodium carbonate and a silicate or fluosilicate with the ore (previously particulated to a fine particle size) at a pH greater than about 7.5 and at a temperature of at least about 30 C., prior to the frothing step and in the absence of both a depressant (of the nature of tannin) and of a collector (of the nature of a water-immiscible carboxylic acid) to make a pulp, conditioning the pulp for a period suificient to provide intimate contact between the ore particles and the silicate and/ or fluosilicate, and thereafter frothing the pulp in the presence of a collector such as a water-immiscible carboxylic acid whereby both calcite and fluorspar rise and are removed as a froth leaving beryllium values in the tails.

As an optional step in the practice of the invention, tannin or quebracho may be admixed with the pulp after the silicate or fluosilicate have been intimately mixed with the ore in the pulp; it is usually added, when employed, at the close of the conditioning period.

The invention oflers a convenient and. effective way of separating beryllium values from the fluorite and the calcite values in bertrandite. Heretofore the calcite did not form a part of the froth during a flotation process but remained in the tails and constituted a source of difliculty due to the contamination of the beryllium values by the calcite. Even in the absence of tannin as a depressant for calcite, this mineral was not floated in sufficient amount to yield a good separation from the beryllium values.

In the practice of the invention, the subsequent separation of the calcite from the fiuorspar in the concentrate or froth is readily accomplished as by admixing it with sufficient additional water and tannin (to suppress the calcite) and subjecting the thus treated froth to an additional flotation treatment whereby the fluorite rises and is separated in the froth.

The invention can be performed on the raw ore as described herebefore or on the tailings of a previous separation whereby most of the fiuorspar has already been floated away.

When raw ore is used, the invention broadly is carried out by crushing and grinding the ore, preferably under water, to the'requisite particle size usually, employing a rod or ball mill. The resulting slurry of ground ore and Water, referred to herein as pulp, is usually then conveyed to a device known as a classifier which separates the fines from the coarse material, the latter being returned to the mill for more grinding. The size of the particles is usually between about 20 and about 200 microns but is preferably largely between about 40 and about 74 microns, an average size of 60 microns being typical. When the material is too fine, it tends to become colloidal and to cause difficulty during subsequent frothing. If it is too coarse, there is insufficient separation of the components of the ore.

Additaments, i.e., agents added to the pulp which are necessary or helpful in the frothing operation according to the invention, must be added in proper sequence at a specified temperature in the grinding mill or in the classifier or special mixing or conditioning tank (when employed) prior to frothing the pulp.

The frothing may advantageously be carried out in stages, i.e., the frothed portion may be subjected to frothing one or more times to effect better separation.

Accordingly, the invention is an improvement in the method of separation of beryllium values from both fluorspar and calcite values in bertrandite ore.

The invention consists essentially of:

(1) Admixing a water-soluble carbonate and a silicate selected from the class consisting of sodium or potassium orthosilicate, sodium or potassium metasilicate, sodium fiuosilicate, potassium fiuosilicate, and mixtures thereof and enough water to wet thoroughly the ore and additaments and grinding the resulting mixture to the desired particle size to make a pulp;

(2) Allowing the pulp to stand accompanied by mild agitation to provide a conditioning period of from about 2 to about 20 minutes (usually about 4 to about 12 minutes) at between about 30 and about 100 C.;

(3) Admixing with the thus conditioned pulp, a carboxylic acid of between about 8 and 24 carbon atoms or a sodium or potassium salt thereof;

(4) Frothing the thus treated pulp by passing a gas, chemically inert to the ore components, usually air, upwardly through the pulp, preferably by admitting the gas, at a controlled rate through a perforated bottom plate or other device designed for such a purpose, until at least a substantial portion of both the calcite and the fluorspar present have risen to form a froth at the surface of the P P;

(5) Drawing off the froth, known as rougher concentrate, containing a preponderance of the calcite and the fluorspar present and leaving behind in the liquid the bertrandite known as rougher tails.

The calcite and the fluorspar may thereafter be separated by known techniques, if desirable, e.g., by refrothing the rougher concentrate in the presence of tannin. The bertrandite in the tails may be further refined, if desired, by known techniques.

Not only does the silicate, used according to the invention, depress quartz, bertrandite, and mixed oxides, e.g., those of iron and aluminum, but it has the effect of activating the calcite to rise.

As earlier stated, tannin or quebracho may advantageously be admixed with the pulp following the intimate mixture of the silicate and/or fluosilicate and prior to admixing the carboxylic acid collector. It is also advantageous to provide a second conditioning stage of from about 2 to about 20 minutes after the admixture of the carboxylic acid or salt thereof prior to the frothing stage.

One embodiment of the practice of the invention 15 to refroth either or both (1) the rougher tails containing a substantial portion of the beryllium values or (2) the rougher concentrate containing a substantial portion of both the calcite and the fluorspar to effect more complete separation.

The broad and the preferred limits of amounts of the preferred materials to employ in each step of the invention are set out below:

Additamelzts per ton of bertrandite ore ADDED DURING OR PRIOR TO GRINDING Additament Broad Limits Preferred Limits Ito 10 lb 2to6lb. 0.5 to 3 lb. 1 to 21b. 0.4 to 0.9 ton 0.5 to 0.7 ton.

ADDED FOLLOWING CONDITIONING Oarboxylic acid or sodium or potas- 0.1 to 10 lb 0.5 to 51b.

sium salt. Water 2 to 4 tons 2.5 to 3 tons.

ADDED DURING FROIHING Inert gas (Suflicient to effect frothing.)

Tannin or quebracho is added optionally, after the silicate and ore mixture has conditioned for a time suffi- For subsequent separation of fluorspar from calcite, additional water and tannin or quebracho are admixed with the concentrate in an amount of between about 0.1 and about 1.2 pounds per ton and preferably between 0.4 to 0.75 pound .per ton of concentrate.

Amounts which are more-or-less than the broad limits set out above may be used, but greater or lesser amounts are not recommended, either for reasons of decreased efficiency or for reasons of economy. The temperature employed in the wet grinding steps is not especially important. However, the temperatures employed in the conditioning and frothing steps are important. Some removal of calcite is attained at conditioning and frothing temperatures of 20 C. but marked improvement is noted at about 30 C. The improvement continues in an impressive manner with increased temperature until about 60 C. has been reached. Thereafter, increases in temperature during frothing up to the boiling point of the pulp results in excellent frothing and separation.

The order of addition of the silicate, tannin (when employed), and the carboxylic acid or salt thereof must be carefully observed in accordance with the order of steps set out above.

In Step 1, i.e., the grinding step, the water, the Na CO usually the commercial grade known as soda ash, and the silicate may be added at the same time or any one thereof may be added prior to the other. Grinding is usually started with the addition of the second of the water, sodium carbonate, or silicate and is continued through and following the addition of the third ingredient until a uniform pulp is obtained. In other words, grinding can be started: (1) after water and soda ash have been added, (2) after water and silicate have been added, or (3) after water, soda ash, and silicate have been added. Tannin,-

tioning step. When most of the additaments are added during grinding, the time consumed by the grinding step is extended to permit intimate mixing of first the silicate, next the tannin (if employed) and then the carboxylic acid with the alkalized ore slurry.

In practice, the soda ash is usually admixed with the 5 ore in the dry state, the water then admixed therewith, and, after at least a substantial part of the water has been added, the silicate is added. The silicate employed is usually either sodium metasilicate or a combination of sodium metasilicate and sodium or potassium fiuosilicate.

The grinding and conditioning periods are such that suificient time is allowed for intimate contact of the silicate, before the tannin (when employed) is added for substantially homogeneous dispersement of each additament.

The following test runs, as shown in Table I, were made, both for the purpose of illustrating the practice of the invention, such runs being designated numbered examples, wherein the objectives of the invention were attained, and for purposes of contrast, such run-s being designated comparative runs and identified by letters, wherein the objectives of the invention were not attained.

The Comparative Runs A to E and Examples 1 to 5 were made on bertrandite ore which had been crushed and ground, in sufiicient water to make a 66 percent by weight total solids, to a fineness such that about 95 percent would pass through a 200 mesh Tyle Standard Sieve. About 20 minutes were required for grinding. In all examples of the invention, prior to grinding, there had been admixed with the ore the amount of soda ash and sodium metasilicate (or sodium metasilicate and sodium fiuosilicate) per ton of ore shown in the table. The examples of the invention include both those wherein tannin was admixed with the ore prior to the flotation stage following admixture of the silicate, and those in which tannin was not used during the flotation stage of the ore.

In Comparative Run A, the temperature was not sulficiently high for a satisfactory separation of the calcite from the bertrandite.

In Test Run C, the tannin was added before the silicate to show the effect of such variation. This can be compared to Example 4 where the silicate preceded the tannin; in both runs, the silicate and tannin were added during the grinding step.

In Test Runs 4, C, 5, D, and E, the rougher concentrate, i.e., the portion frothed over from the ore was refrothed (designated 4-a, C-a, 5-a, Da, and E-a) in the presence of a small amount of tannin only, to separate the calcite from the CaF the former being, depressed and forming the cleaner tails and the latter being recovered from the froth or cleaner concentrate. The refrothing step was carried out by adding to the rougher concentrate (l) sufiicient water to make about 25 percent total solids and (2) the amount of tannin shown in Table I and refrothing at C. until the amount of fiuorspar shown in Table I, as cleaner concentrate, had been frothed over. The average length of time for this refrothing period was about 5 minutes.

TABLE I Pounds Added/Ton of Temp., C. Percent Recovery Bertrandite Ore Test Source of Bertrandite Run Ore being Treated Remarks 1 Rougher Cleaner No. Soda Sodium Oleic Condi- Froth- Concentr. Concentr.

Ash Meta- Tannin Acid tioning ing silicate (JaCo CaF CaCO CaF A"... Raw Ore Tannin added in 6 1 0.75 2 20 conditioner.

6 1 0. 75 2 40 6 1 0. 75 2 do G 1 0.75 2 100 a No silicate added, 6 None 0. 2 60 Tannin added in 6 1 0 75 2 grinder. 4-a. Rougher Concentrate Tannin added for None None 0.1 None 55 from 4 above. refrothing. C Raw Ore Tannin added in 6 1 0 75 2 100 grinder, before silicate. Ca Rougher Concentrate Tannin added for None None 0.1 None 55 55 .t 21. 3 91. 5

r from 0 above. refrothing. 5 Raw Ore No tannin 6 1 None 2 100 60 67.9 97. 5 5a Rougher Concentrate Tannin added for None None 0. 1 None 55 55 41. 5 91. 4

from 5 above. refrothing. D Raw Ore Nodsligate or tannin 6 None None 2 100 60 45. 7 90. 0

a e D-a- Rougher Concentrate Tannin added for None None 0. 1 N one 55 55 21. 1 75. 6

from D above. refrothing. E Raw Ore No silicate 4 None 0.75 2 100 60 39. 6 96 8 E-a Rougher Concentrate Tannin added for None None 0. 1 None 55 55 20. 1 94. 6

irorn E above. refrothing.

1 In Runs A, 1, 2, 3, the tannin was added during the conditioning step. In Runs 4, C, and E, the tannin was added during the grinding step. In all Runs where both silicate and tanning were used, the silicate preceded the tanning except in Run 0.

Comparative Run A and Examples 1 to 3 of Table I show the improved effect of increasing the temperatures during conditioning and frothing. To illustrate, when conditioning and frothing was carried out at 20 C., only 37.3 percent of the calcite was removed in the froth whereas when conditioning and frothing was carried out at 40 C., 83.5 percent of the calcite was removed, and when conditioning was at 60 C. or 100 C. and frothing was at 60 C., about 89 percent of the calcite present in the ore was removed in the froth.

Comparative Run B shows that when no silicate is present, only 45.7 percent of the calcite in the ore was removed in the froth. This is unsatisfactory. In Example 2 which was run the same as Run B, except that silicate was added according to the instant invention, 88.6 percent of the calcite was removed in the froth.

Example 4, which had the tannin added during the grinding step, but following the addition and mixing of the silicate, shows that 63.4 percent of the calcite present in the ore and 94.6 percent of the fluorite present in the ore were removed in the rougher froth. This example,

ore tailings and sufiicient water to give a 66 percent by weight total solids. Grinding was continued for 20 minutes until 90 percent was sufficiently fine to pass through a No. 325 (44 micron-size opening) mesh screen. The pulp so made was then conditioned for 5 minutes at C. and then frothed for 5 minutes at 40 C. at a pH between 9.6 and 9.9 to produce the rougher concentrate and leaving rougher tails having the assay and representing the percents of various components, based on that originally present in the ore tailings from the conventional treatment, as set out in Table II below. After frothing the conventionally produced ore tailings, the rougher tails were removed, the rougher concentrate returned to the frother and refr-othed at 50 C. in the presence of 1 pound of sodium metasilicate per ton of concentrate for an additional 5 minutes during which the pH dropped to 9.2. A froth or cleaner concentrate was thereby produced which had the assay and represented the percent of components originally present in the ore (prior to treatment by the conventional method) that are set out in Table II.

TABLE II (EXAMPLE 6) Assay in Percent Percent of Component based on Ore prior Weight to Treatment Units B CaCOa CaF; Acid In- Be C3003 Cal] Acid Insolubles solubles Rou her tails from 1st frothin sta e according to ingemiomf 84.5 2.41 18.2 2.7 79.1 53.2 11.2 0,8 7, Cl t ls from 2d frcthin sta e accor ing 0 tii i fivgitd 37.0 2.13 27.2 19.1 53.1 26.1 7.2 2.7 ml Cleaner concentrate (from 2 mt ing 5 age according to the invention) 278.0 0.21 66.7 3.2 20.5 81.2 96.5 12,2

compared to Example 3, shows that better calcite and fiuorspar removal is obtained by adding the tannin during the conditioning period than during the grinding step. (In Example 3, the silicate was added during grinding and the tannin added during conditioning.)

In comparative Run C, wherein the tannin was added during the grinding step and prior to the silicate, the results are not satisfactory since only 35.5 percent of the calcite in the ore was removed in the froth, i.e., rougher concentrate.

Example 5 shows that when the silicate is added prior to frothing, even in the absence of subsequently added tannin, that the rougher concentrate contained 67.9 percent of the calcite and 97.5 percent of the fiuorspar originally present in the ore.

Comparative Run D shows that when neither tannin nor silicate is present during frothing, that the results are poor, as shown by a recovery of only 45.7 percent calcite and 90.0 percent fiuorspar in the rougher concentrate.

Comparative Run E shows that when no silicate is present, that the percent of calcite in the rougher concentrate is only 39.6 percent, although fiuorspar removal is satisfactory.

An additional test run, numbered Example 6, was made to show that the ore tailings of a flotation treatment of bertrandite ore, which had been conducted in a conventional manner, employing tannin, Na CO and oleic acid, can be treated according to the invention.

This example was carried out by scrubbing the tailings to remove substantially, from the surface of the ore particles, any residual tannin and oleic acid from the previous treatment. This ore was put in a ball mill and intermixed with 2 pounds of soda ash, 2 pounds of sodium silicate, and 0.3 pound of oleic acid per ton of Reference to Table II shows that treatment of the tailings of bertrandite ore resulting from conventional treatment may be advantageously treated according to the invention to effect separation of calcite from the fiuorspar.

Example 7 Another test run, similar to Example 6, was run wherein rougher tails from a conventional flotation process, which employed only tannin, Na CO and oleic acid were scrubbed to remove oleic acid and tannin and then treated according to the invention except that both sodium metasilicate and sodium fluosilicate were used. This example was carried out as follows:

The scrubbed tailings used were ground as a 66 percent by weight total solids aqueous slurry containing 4 pounds of soda ash, 2 pounds of sodium metasilicate, and 4 pounds of sodium fluosilicate per ton of scrubbed tailings (which constituted the ore feed) to a fineness such that percent were sufiiciently small to pass through a 200 mesh Tyler Sieve. 3 pounds of oleic acid per ton of the pulp were then admixed therewith and the resulting pulp conditioned at C. for 5 minutes, then cooled to 60 C., and frothed at that temperature for 5 minutes. The froth or concentrate so made was refrothed at 5 0 C. for 5 minutes. No ingredients were added during the refrothing stage. The final pH value was 8.5. The assay of the rougher tails prepared during the first frothing of the scrubbed tailings, the assay of the cleaner tails and the assay of the cleaner concentrate are set out in Table II. The assay in percent by weight is based upon the total components in the particular tails or concentrate being assayed. The percent of each component, based upon the amount of each component present in the scrubbed tailings, are also given in Table III.

TABLE III (EXAMPLE 7) Assay in Percent Percent Recovery Based on the Ore prior to Conventional Treatment Weight Units Be CaCOa Cal Acid In- Be CaCO; Call; Acid Insolubles solubles Rougher tails 86. 5 1. 34. 7 17. 3 44. 6 68. 0 32.0 4. 72. 7 Cleaner tails 36. 0 0. 57 52. 3 24. 3 20. 6 16. 0 20. 0 2. 6 14. 0 371. 0 0. 0548 12. 1 84. 0 l. 9 16. 0 48. 0 92. 9 13. 3

1 Tails remaining after first frothing of scrubbed tailings of conventional process. 2 Tails produced after frothing of rougher concentrate made by first frothing step according to the invention.

3 Concentrate made by Irothing of rougher concentrate of (2).

This example, when compared with Example 6, shows that a mixture of both sodium silicate and sodium fluosilicate (with soda ash) is more effective than sodium silicate alone in preventing the flotation of beryllium values present in the bertrandite. It also shows that when no additional silicate is added before frothing the rougher concentrate, that the beryllium is not depressed as much as when silicate was present in the first frothing. It is to be noted that when silicate was used in the first frothing step, 68 percent of the beryllium values remained in the rougher tails. In the second frothing step, only about one-half of the beryllium values that were in the rougher concentrate remained in the cleaner tails.

Further comparison of Examples 6 and 7 shows that employing both sodium silicate and sodium fluosilicate caused a greater percent of the beryllium values to remain in the rougher tails than when sodium silicate alone was used. At the same time the sodium silicate alone caused better flotation of the calcite than the mixture of silicates did. Thus one can choose a combination of silicates which will give the most desired effect.

The examples show that both fluorspar and calcite can be floated off and thereby the beryllium values separated from fluorspar and calcite in bertrandite ore by admixing the selected ingredients in proper order and observing the temperature conditions required by the practice of the invention.

Having described the invention, what is claimed and desired to be protected by Letters Patent is:

1. The method of recovering beryllium values substantially free from fluorspar and calcite found in bertrandite ore consisting of (1) grinding the ore in about a 60 to about 70 percent total solid aqueous slurry containing, per ton of ore, between about 1 and about 10 pounds of soda ash, between about 1 and about 2 pounds of a silicate selected from sodium and potassium metasilicates and orthosilicates, sodium and potassium fluosilicate, and mixtures thereof, to a particle size such that at least about 95 percent will pass through a 200 mesh sieve and about 75 percent will pass through a 325 mesh sieve, to make a pulp, and subsequently adding water to dilute the solids to about 25 to about 30 percent and conditioning the pulp at a temperature of from about 30 C. to about 100 C. for a period of from about 2 to about minutes and (2) passing a gas which is chemically inert to the pulp upwardly through the pulp in the presence of between about 0.5 and about 5.0 pounds, per ton of ore present, of a C to C carboxylic acid at a controlled rate, at a pulp temperature of between about 30 C. and about 100 C., whereby both calcite and fluorspar are caused to rise as a froth and to overflow as a concentrate, thus effecting a separation thereof from the beryllium values.

2.. The method according to claim 1 wherein tannin in an amount of between about 0.1 and about 1.2 pounds per ton of the ore is admixed with the pulp following the addition of the silicate during the conditioning period and prior to the flotation step in the presence of the carboxylic acid.

3. The method according to claim 1 wherein the froth there produced is admixed with suflicient water to give about a 25 to about 30 percent total solids and the pulp so made is refrothed at a temperature of between about 30 C. and about C. to yield a cleaner concentrate which contains a greater amount of calcite and a lesser amount of beryllium values.

4. The method according to claim 3 wherein between about 1 and about 4 pounds, per ton of concentrate solids, of a silicate, selected from the class consisting of sodium and potassium metasilicates and orthosilicates and sodium and potassium fluosilicate, and mixtures thereof, are added to the concentrate froth prior to being refrothed.

5. The method according to claim 1 wherein the silicate added consists of both sodium metasilicate and sodium fluosilicate.

6. In a flotation method of recovering beryllium values, which are substantially free from calcite, from bertrandite ore tailings produced by a previous flotation step wherein there was employed an agent selected from the class consisting of tannic acid, tannin, a carboxylic acid, and mixtures thereof during said previous flotation step, and whereby fluorspar concentrate had been removed from said ore as a froth, the improvement comprising scrubbing said bertrandite ore tailings to remove residual tannic acid, tannin and carboxylic acid and subjecting the thus scrubbed tailings to the flotation method according to claim 1, thereby to remove substantially all of the calcite and any remaining fluorspar as overflow froth, and tailings of increased beryllium content are recovered substantially free from calcite and fluorspar.

References Cited by the Examiner UNITED STATES PATENTS 2,168,762 8/1939 Clemmer 209-166 2,471,414 5/1949 Dasher 20911 X 3,028,008 3/1962 Browning 209-166 X 3,078,997 2/ 1963 Havens 209167 X 3,207,304 9/1965 Thom 209-167 X OTHER REFERENCES US. Bureau of Mines R1. 4040, March 1947, pp. 3-9. Chemical Abstracts 57, 14771 f, Eigeles (1962).

HARRY B. THORNTON, Primary Examiner.

R. HALPER, Assistant Examiner.

Claims

1. THE METHOD OF RECOVERING BERYLLIUM VALUES SUBSTANTIALLY FREE FROM FLUORSPAR AND CALCITE FOUND IN BERTRANDITE ORE CONSISTING OF (1) GRINDING THE ORE IN ABOUT A 60 TO ABOUT 70 PERCENT TOTAL SOLID AQUEOUS SLURRY CONTAINING, PER TON OF ORE, BETWEEN ABOUT 1 AND ABOUT 10 POUNDS OF SODA ASH, BETWEEN ABOUT 1 AND ABOUT 2 POUNDS OF A SILICATE SELECTED FROM SODIUM AND POTASSIUM METASILICATES AND ORTHOSILICATES, SODIUM AND POTASSIUM FLUOSILICATE, AND MIXTURES THEREOF, TO A PARTICLE SIZE SUCH THAT AT LEAST ABOUT 95 PERCENT WILL PASS THROUGH A 200 MESH SIEVE AND ABOUT 75 PERCENT WILL PASS THROUGH A 325 MESH SIEVE, TO MAKE A PULP, AND SUBSEQUENTLY ADDING WATER TO DILUTE THE SOLIDS TO ABOUT 25 TO ABOUT 30 PERCENT AND CONDITIONING THE PULP AT A TEMPERATURE OF FROM ABOUT 30*C. TO ABOUT 100*C. FOR A PERIOD OF FROM ABOUT 2 TO ABOUT 20 MINUTES AND (2) PASSING A GAS WHICH IS CHEMICALLY INERT TO THE PULP UPWARDLY THROUGH THE PULP IN THE PRESENCE OF BETWEEN ABOUT 0.5 AND ABOUT 5.0 POUNDS, PER TON OF ORE PRESENT, OF A C8 TO C24 CARBOXYLIC ACID AT A CONTROLLED RATE, AT A PULP TEMPERATURE OF BETWEEN ABOUT 30*C. AND ABOUT 100*C., WHEREBY BOTH CALCITE AND FLUORSPAR ARE CAUSED TO RISE AS A FROTH AND TO OVERFLOW AS A CONCENTRATE, THUS EFFECTING A SEPARATION THEREOF FROM THE BERYLLIUM VALUES.