US1819112A - Froth flotation of minerals - Google Patents

Description

1 tion will be apparent No Drawing.

Patented Aug. 18, 1931 warren STATES PATENT oF1-"1c ROBERT L. PERKINS, OF EAST AURORA, NEW YORK, ASSIGNOR TO NATIONAL ANILINE & CHEMICAL COMPANY, INC.,

OF NEW YORK, N. Y., A CORPORATION OF NEW YORK rRoTH FLOTA'IION or MINER-Ans agents in the froth flotation of minerals and ores. Another object of the invention is the preparation of new organic compounds which are esters of alkyl or aralkyl xanthic acids. These and other objects of the invenfrom a consideration of the following disclosure which is'given for the purpose of illustrating the invention.

Metal xanthates (metal salts of alkyl Xanthic acids) have been prepared, as is well known, by reacting an alcohol with carbon bisulfide and a suitable metal hydroxide, and it has been heretofore proposed to employ such xanthates as modifying orcollectiing agents in the froth flotation of minera s.

It has beenfound that by the treatment of a suitable metal xanthate with a suitable aryl or aralkyl derivative, esters of alkyl and aralkyl xanthic acids can be 'obtainedwhich contain an 'aryl nucleus in their composition and which correspond with the probable formula:

' ROCSSR' wherein R is an alkyl or aralkyl radical (such a 2 5-3 3 1 4 9 a ing agents when einployed in the separation Application filed April 22,

1929/ s m No. 357,338.

of minerals and concentration of ores by froth flotation; particularly when R in the above formula is a hydrocarbon radical which contains a position, and especially when R isa hydrocarbon radical of the benzene series, specifically a phenyl radical.

n preparing the esters of the present invention' according. to a preferred method of procedure, an alkali-metal salt of an alkyl or aralkyl 'xanthic acid is reacted with a diazo salt of an aromatic compound, or with a halide of an aryl-aliphatic compound, preferably in a suitable solvent or diluent; such as, water, alcohol, and the lik The phenyl radical in its combodies thus obtained are the crude estersv of the present invention. They are generally oils substantially insoluble in water and soluble in ether (and benzene. If desired, the crude esters can be purified by a suitable treatment.

In utilizing the said esters in the froth flotation of minerals and the concentration of ores, the mineral or ore is subjected to froth flotation in the presence of one or more of s'aidesters, which may be either crude or purified, andwhich may be incorporated with the ore or the mineral pulp in any suitable manner and at any suitable time that will produce satisfactory flotation. Thus,.they may beadded to the orewhile it is being reduced to a pulp, or they may be added to the pulp either before or after its introduction into the flotation machine they may, if necessary, be used in conjunction with a suitable or well known frothing agent, such as, pine may be employed in a neutral, alkaline or acid circuit; although a non-acid circuit is preferred; they may be employed in admixture with each other or with other suitable flotation reagents, such as, the organic sul fides, polysulfides, other xanthates, etc.; and they may be added as such or in the form of a solution or suspension in a suitable solventor suspension medium, such as, water, a

. dry ore will be suificient for satisfactory operation.

For a better understanding of the invention, reference should be had to the following specific examples wherein are described and illustrated representative products and methods for producing and employing said products in accordance with the invention; but it is to be understood that the invention is not limited thereto. The parts are by weight.

.Aryl esters of xanthic acids E wample 1 Phenyl ester of methyl xanthic acids.9.3 parts of aniline is diazotized in the usual manner with sodium nitrite and hydrochloric acid, and the solutions are treated with sodium carbonate solution until faintly acid to Congo red paper. 14.7 parts ofpotassium methyl xanthate are dissolved in about 100 parts-of water at about 80 C. The diazotized aniline solution is slowly run into the warm agitated xanthate srlution, nitrogen being given off in the reaction. Care is taken to prevent the reaction from foaming .over due to the too rapid evolution of nitrogen. Upon completion of the addition of the diazo solution, the reaction mixture is agitated for an additional hour and then allowed to stratify by standing for about an hour. The oil which separates is removed from the aqueous layer, isfiltered with suction, is washed, first with dilute caustic alkali,

then with dilute acid, and then with water until the Wash water reacts neutral to Congo red paper, and is dried over anhydrous sodium sulfate. The phenyl ester of methyl xanthic acid thus obtained has the probable formula CH OCSSC H and is a dark red- C brown oil, very slightly soluble in water, and

readily soluble in ether. If desired, the ester 7 can be further purified by distillation with steam, extraction of the distillate with ether, and evaporation of the ether from the extract;

E mample 2: Tolyl ester of isopropyl mamtkz'c acid.60 parts of isopropyl alcohol, 40 parts of sodium hydroxide and 7 6 part-s of carbon bisulfide are mixed with agitation while maintaining the temperature between about 20 to 28 C. 38 parts of the resulting crude sodium isopropyl xanthate is dissolved in about 300 parts of water, and the excess alkali is neutralized with hydrochloric acid until neutral to Clayton yellow paper. 21.4 parts of o-toluidine are diazotized with sodium nitrite and hydrochloric acid in the usual manner, the solution is treated with sodium carbonate solution until faintly acid to Congo red paper, and the resulting o-diazo-toluene chloride solution is gradually added to the aqueous isopropyl xanthate solution heated to a temperature of about C. The temperature rises to about 90 to 95 C. Upon treating the resulting reaction mixture in the manner described in Example 1, the o-tolyl ester of isopropyl xanthic acid having the probable formula c11ocssc@u.crn OH: is obtained as a red-brown oil, soluble in ether and benzol, and very slightly soluble in water.

If, in the above examples, there are substituted for the alkali-metal xanthates therein employed corresponding molecular proportions of other suitable salts of alkyl or aralkyl xanthic acids (e. g., sodium methyl xanthate, alkali-metal salts of normal propyl xanthic acid, of normal and iso-butyl xanthic acids, of normal and iso-amyl xanthic acids, of normal hexyl xanthic acid, of normal heptyl xanthic acid, of normal octyl xanthic acid, of normal nonyl xanthic acid, of benzyl xanthic acid, of phenyl ethyl xanthic acid, of cyclo-hexyl xanthic acid, etc.) and/or there are substituted for the salts of diazotized aniline and o-toluidine therein employed corresponding molecular proportions of other salts of diazotized aryl amines (e. g., the chlorides or sulfates of diazotized p-toluidine, of diazotized xylidine, of diazoti-zed cumidine. of diazotized benzidine, of diazotized anisidines, of diazotized alphaor beta-naphthylamines, of diazotized betaamino anthraquinone, and the like) corresponding aryl esters of alkyl or aralkyl xanthic acids may be obtained. These esters are all included in the probable, general formula ROCSSR wherein R is CH C H ,C H,, C5H11, e 1s C7H15'", s i7' C9H19 7 H or an aralkyl radical; and R. is an aryl radical.

Instead of a diazotized arylamine, an aralkyl halide (e. g., benzyl chloride or bromide, phenyl ethyl chloride or bromide, triphenyl methyl chloride or bromide. etc.) may be reacted with a metal salt of an alkyl .or aralkyl xanthic acid, as illustrated in the following example, whereby aralkyl esters of alkyl or aralkyl xanthic acids may be obtained having the probable, general formula:

ROCSSR Ara-llc yl esters of wanthz'c acids Example 3: Benzy l ester of ethyl xanthic acid.12.6 parts of benzyl chloride are mixed with 16.1 parts of potassium ethyl xanthate and 80 parts of ethyl alcohol (denatured), and the mixture is continuously agitated at room temperature for'several hours. The resulting mixture is added to about 1,000 parts of water, the water layer is drawn off. and the oil is again washed with about 500 parts of water. The mixture is filtered and the filtrate is allowed to stratify. The oily layer is separated from the aqueous layer, dried over anhydrous sodium sulfate, then over of phenyl ester of ethyl calcium chloride, and thenvacuum distilled. The benzyl ester of ethyl xanthic acid thus obtained is apractically colorless liquid having a faint odor. It does not solidify at 0 (3., boils at a temperature of about 17 25 1]. (corn) under 15 millimeters pressure, is soluble in alcohol to the extent of about 1 part in 6 parts of alcohol at 21 (3., is very slightly soluble in water, and readily soluble in ether and benzol. It has the probable formula, C H OCSSCH C H Flotation 'of minerals Example 4-500 parts of a copper sulfide ore (from the Chino mine of the Nevada Consolidated Copper Co., Hurley, N. M.) assaying 1.26 per cent copper, were ground in a ball mill with 215 parts of water and about 0.7 parts hydrated lime (equivalent to about 3 pounds hydrated lime perton of dry ore) until practically all of the mixture was sulficiently fine to pass a 40 mesh screen (about 1 hour). The ground pulp was diluted with sufficient Water to give a mixture containing about 16 per cent solids, and about 0.054 parts xanthic acid,

. c mocssdm,

(equivalent to about one-fifth pound per ton of dry ore) was added. The mixture was subjected to agitation in a J anney flotation apparatus for a few minutes, then a small amount, e. g., 0.02 to 0.03 parts, ofpine oil Was added, and agitation and flotation were carried out for about 15 minutes with addition of about 0.02 to 0.03 more parts of pine oil. The rougher concentrate thus obtained was refioated for about 5 minutes without any additional flotation agent but with the addition of another small amount of pine oil. 27.5 parts of a cleaner concentrate assaying 19.18 per cent copper were obtained. A re-' covery of about 84 per cent ofthe copper was therefore obtained in the cleaner concentrate. The tailings assayed "0.145 per cent copper. The equivalent of about 18.3 tons of ore was required to give about 1 ton of concentrate.

Example 5,-500 parts of copper sulfide ore (from the Chino mine of the Nevada Consolidated Copper Go.) assaying 1.33 per cent formula wherein R- is CHF,

copper were treated as described in Examdrated lime (equivalent to about 4 pounds per ton of dry ore) and about 0.05 part of phenyl ester of methyl xanthic acid, oH.0osso.H., produced as escribed in Example 1, (equivalent to about 0.2 pounds per ton of dry ore) were employed. 10.6 parts of a' concentrate assaying 42.90 per cent copper were obtained. The tailings assayed 0.25 per cent copper. This illustrates the high selective action of the esters of the present invention with respect tocopper sulfide minerals.

In a similar manner other aryl and aralkyl esters of alkyl and aralkyl xanthic acids may be employed as collecting agents in the froth flotation of minerals and the concentration of'ores. i

It will be understood that the invention is not limited to the specific examples given above, butmay be varied within wide limits metal xanthates may be employed, and even i the crude reaction mixture resulting from the reaction of an alcohol, carbon disulfide and an alkali-metal hydroxide may often be used. The diazo-aromatic salts employed may be prepared in any suitable manner, preferably by the diazotization of the corresponding primary aromatic amine. I

I claim:

1. A composition of matter comprising an ester of a xanthic acid having the probable formula 1 ROCSSR' wherein R is 'CH C H 5 11 O6H13, 07H C9H 9 06H R'is an aryl C4H9 7 15 s 17 or an aralkyl radical; and or aralkyl radical.

. 0 X A compos1t1on of matter COIIIPIlSll'lg an ester of a xanthic acid having the probable ROCSSR 3 71 C4H9 C5H11 c 1s 7 15 a 11 9 C H or an aralkyl radical; and R is a hydrocarbon radical which contains a phenyl radical in its composition.

3. A composition of matter comprising an ester of a xanthic acid having the probable C H C H and R is. anaryl or aralkyl radical.

ester of a xanthic acid having the probable formula ROCSSR wherein R is CH C I-I C H C5H117 e 13 i 15 s 17 C H C H or an aralkylradical; and R is an aryl radical.

5. A composition of matter comprising an ester of a xanthic acid having the probable formula ROCSSR" C H C H or an aralkyl radical; and

R" is a hydrocarbon radical of the benzene serles.

6. A composltion of matter comprising an ester of a xanthic acid having the probable formula C9I-I C H or an aralkyl radical; and R" is a phenyl radical.

7 A composition of matter comprising an ester of an alkyl Xanthic acid having the probable formula ROCSSR" 8. A composition of matter comprising an ester of an alkyl xanthic acid having the probable formula C I-I or C H and R is a hydrocarbon radical of the benzene series.

9. A composition of matter comprising an ester of an alkyl xanthic acid having the probable formula C H or C I-I and R" is a phenyl radical.

10. A composition of matter comprising an ester of an alkyl xanthic acid having the probable formula nocss'ofins 11. In the separation of minerals by flotation, the step which comprises subjecting a mineral pulp to a froth flotation operation in the presence of an ester of a xanthic acid having the probable formula ROOSSR wherein R is an alkyl or aralkyl radical, and R is an aryl or aralkyl radical.

12. In the separation of minerals by flotation, the step which comprises subjecting a mineral pulp to a froth flotation operation in the presence of an ester of a xanthic acid having the probable formula ROCSSR' ROCSSR wherein R is an alkyl or aralkyl radical, and R is a hydrocarbon radical which contains a phenyl radical in its composition.

14. In the separation of minerals by flotation, the step which comprises subjecting a mineral pulp to a froth flotation operation in the presence of an ester of a Xanthic acid havingthe probable formula ROCSSR wherein R is an alkyl or aralkyl group and R" is an aryl radical.

15. In the separation of minerals by flotation, the step which comprises subjecting a mineral pulp to a froth flotation operation in the presence ofv an ester of'a xanthic acid having the probable'formula ROCSSR wherein R is an alkyl or aralkyl group and R is a phenyl radical.

16. In the separation of minerals by flotation, the step which comprises subjecting a mineral pulp. to a froth flotation operation in the. presence'of an ester of an alkyl xanthic acid having the probable formula ROCSSR' wherein R is an alkyl group and R is an aryl or aralkyl radical.

17. In the separation of minerals by flotation, the step which comprises subjecting a mineral pulp to a froth flotation operation in the presence of an ester of an alkyl xanthic acid having the probable formula ROCSSR wherein R is an alkyl group and R is a hydrocarbon radical which contains a phenyl radical in its composition.

18. In the separation of minerals by flotation, the step which comprises subjecting a mineral pulp to a froth flotation operation in the presence of an ester of an alkyl xanthic acid having the probable formula nocssa" wherein R is analkyl group and R" is a phenyl radical. y

19. In the separation of minerals by flotation, the step which comprises subjecting a mineral pulp to a froth flotation operatlon in the presence of an ester of an alkyl xanthic acid having the probable formula ROGSSCBI-L wherein R is an alkyl group. a

20. In the separation of minerals by flotation, the step which comprises subjecting a copper sulfide mineral pulp to a froth. flotation operation in'- the presence of an ester of a xanthic" acid having the probable formula ROCSSR' wherein R is an alkyl or aralkyl radical,

and R is an aryl or aralkyl radical.

21. In the separation of minerals by flotation, the step which comprises subjecting a copper sulfide mineral pu p to a froth flotation operation in the presence of an ester of a xanthic acid having the probable formula ROCSSR" wherein R isan alkyl or aralkyl group and R is a phenyl radical.

22. In the separation of minerals by flotation, the step which comprises subjecting a copper sulfide mineral pulp to a froth flotation operation in the presence of an ester of an alkyl formula xanthic acid having the probable ROCSSR' wherein R is an alkyl group and R is a aryl or aralkyl radical.

23. In the separation of minerals by flotation, the step which comprises subjecting a copper sulfide mineral pulp to a froth flotation operation in the presence of an ester of an alkyl xanthic acid having the probable formula aocss can,

wherein R is an alkyl group. p

In testimony whereof I aflix my signature.

ROBERT L. PERKIN