US2414199A - Froth flotation of nonsulfide ores - Google Patents

Description

Patented Jan 14, 1947 UNITED STATES, PATENT OFFlCEf FROTH FLOTATION F NONSULFIDE ORES Gregoire Gutzeit, Westport, Conn.

No Drawing. Application September 8, 1943,

Serial No. 501,563

The present invention relates to flotation, and more particularly to therecovery of desired minerals from ores containing the same by application of froth flotation methods.

It is an object of the invention to provide an improved flotation procedure in which, through the application of a chemical principle not heretofore recognized in the flotation art, unwanted gangue materials are deactivated or depressed and thereby largely eliminated from the concentrate of desired minerals, thus improving the grade of the concentrate to a marked degree. It is also'an object of the invention to provide an improved flotation procedure in which, through the application of the same chemical principle, a selective separation can be made between two valuable minerals.

Froth-flotation is roughly based on the fact that the surface of a given mineral to be recov ered can be rendered, by the action of so-called collectors, more or less water repellent, i. e. aerophil, and a mineral-air complex, the specific gravity of which is lower than that of the pulp, is thus formed with the air bubbles introduced into the pulp. The binding of the collector to the mineral surface by chemical reaction, chemoadsorption, adsorption, etc., is due to e1ectrostatic forces, i. e. unsaturated valences, both of the collector itself and of the said surfaces.

It is the custom to speak about differential flotation, only in the case of polymetallic concentration, but most of the usual monometallic flotations are also differential ones, as the gangue has to be prevented from floating together with the wanted mineral. If the used collector has a tendency to be adsorbed by the gangue (which is particularly the case of paraflinic oils, fatty acids, fatty alcohols, sulfated= and sulfonated alkyl-compounds, etc., chiefly used in the flotation of metallic oxide ores and non-metallic ores), the latter must be depressed. Roughly, depression consists in the action of preventing the binding of the collecting reagent to the surface of a certain mineral which is not wanted in the concentrate. In the case of monometallic flotation, the gangue minerals which are mostly quartz and silicates, but which may also be carbonates of the alkaline earths, 'must be depressed. In the case of polymetallic flotation, the gangue, together with other valuable metallic minerals, have to be kept from floating, or a single mineral has to be collected, while others are prevented from concentrating in the froth.

Although the usual gangue minerals (with a few exceptions like talc, graphite, etc.) when pure, are naturally more hydrophilic than the valuable metal-bearing ones, they are easily floated after activation with metallic cations. Thus,'quartz and most other silicates may be activated by very small amounts of iron, copper, zinc,

1 lead, nickel, tin, titanium, barium, and some other 4 Claims. (01. 209-166) cations, and calcite by barium, copper, iron, and lead salts when floated with fatty acid or fatty alcohol collectors at pH values varying with each activating ion. Since in almost every pulp there are soluble metallic salts present such as dissolved .iron from the ball-mill, or copper, zinc, or iron sulfates from the oxidization of sulfide-minerals, the gangue is always more or less activated and tends to concentrate in the flotation froth. This is particularly true when anion active high molecular aliphatic acids and alcohols, or their derivatives are used as collectors. In order to keep the gangue from floating, it is usual to add alkalies such as sodium carbonate, sodium hydroxide and the like, or sodium silicate, or acids. Alkalies form easily wettable hydroxides with the activating cations and'increase the hydrophilic character of quartz and the silicates by their tendency to form soluble alkali-silicates. Sodium silicate forms insoluble metallic-silicates and hydrated metallic silica gels with the activating cations. The acidification of the pulp tends to replace the adsorbed metallic cations by more positive hydrogen ions which are hydrophilic, and increases the solubility of certain minerals. In addition to the effect of the alkalies, the use of alkali cyanide for the depression of the gangue has been proposed. Cyanide forms soluble complexes with some activating heavy metal cations, removing them by means ofthis reaction from the gangue material.

It will be seen, therefore, that in the flotation of ores, chemical and physical control is directed, flrstly, toward increasing the flotability of the wanted minerals and, secondly. towardminimizing any flotation tendency exhibited by theun- 'wanted gangue minerals contained in the admixture.

present so as to prevent the activation and flotation of unwanted gangue minerals by the agency of such cations.

Broadly, the invention embraces the addition to a flotation pulp of an organic compound able to form very stable, water soluble, or insoluble, but hydrophilic, inner complexes (chelate compounds) with the extraneous metallic cations in solution or adsorbed on the mineral particles, whereby such ions are prevented or inhibited from exerting an activating effect on the gangue particles.

Activation of thegangueminerals by metallic ions has been proved the fundamental condition for their flotation with cationic collectors of the fatty acid type. A. M. Gaudin and Alfonso Rizo fi 'l P..N.o. 1453, A. I. M. E., February 1942,

, ,latter has to be depressed.

have studied the mechanism of quartz activation takes place in alkaline pulp, after abstraction of barium ions, the optimum ratio of collector to activating ion being 1:1. The mechanism of this 1 cation adsorption is postulated to be a result of the ruptured bonds on the quartz surface, and the maximum barium-ion adsorption is calculated to be 1.7 micromol.

Following L. Kraeber and A. Boppel (Metal 8: Erz, XXXI, 19), the cations listed below will definitely activate quartz within the indicated pI-I'range:

pH range e s s??? Theyions Ll' Ce++++, Zn++ (ph 7 9 1++ are less effective. W. Halbich proved that cal-cite -barium salts using oleic acid as collector, and demonstrated that effective quartz flotation only' aeration:

iBroadly this second application of the invention embraces the addition to a flotation pulp of an organic compound able to form very stable,

water-soluble or insoluble but hydrophilic innerconiplexes- (chelate compounds) with the metal lic cations of one of the mineral-s,'whereby.suchminerals are prevented from being reacted upon by the collector, 'andthus inhibited from concentrating in-the flotationfrothl, -It is very. probable that" even normal collectionof; saypchalcocite (copper sulfide) is dueto the-presence'of adsorbed copper ions on the surface of the mineral (auto-activation). But even if, thistheory isnot generally admitted, the formation of a hydrophilic complex with the metal atoms of the lattice would cause depression.

According to the accepted theory of ionization, soluble salts are dissociated to a greater or lesser extent into their respective positively charged cations and negatively charged anions, thus:

cuc1iz= cii+i+2cr Furthermore, these elements are in ,a state of equilibrium and any change in the concentration of molecular (left) or ionic (right),-components results in more or less dissociation, depending upon the direction of displacement.

The Cu++ ions with their two positive, elementary charges are thus in a positionv not only to bind anions with an opposite chargeand so to form new compounds by the simple process of stoichiometric chemical reaction (by electro- -'valence), but also to'neutralize (by coordination ha been performed with collectors which-are mainly fatty acids, higher aliphatic alcohols, or derivatives thercofx; 'I'hese collector's, unlike for example, the xanthateshsed in the flotation of sulphides, are not very specific but have marked tendency to float the whole crude ore comprising .the gang'ue (provided activation tookplace). As

the aim of flotation is selective separation between the valuable mineral and the gangue, the

As stated above, silica, thesilicates, baryte and many light metal carbonates willunot bind the fatty acidcompounds chemicallyv by themselves, but only by the intervention of adsorbed cations. If these extraneous activating cations. can be rendered harmless by a chemical which will'tie them up and remove them asan active factor in the process, the gangue minerals will exhibit no tendency to contaminate the concentrate. As the binding of the cation in an undissociable inner complex is quite complete, the proposed .aim is fulfilled by the use of organic reagents able toform .suchcomplex compounds. However, at the same time, all excess cations are satisfled'and yielded into an undis-sociable complex wherebyreadsorption of the cations by the gangue i precluded.

In the field-of selectiveflotation, the present invention makes possible the specific depression v of one or several mineralsgby addition of an ex cess (over 0.2'5 kg./t.) of the organic compounds to be described, for reacting with the cations at the surface of the mineral so as to prevent flotation by rendering said surface hydrophilic or water-avid.

valence)- the charge which exists on dipolar compounds, that is, molecules possessing an unbalanced or asymmetric electric field. In the former case a. new ionic copper compound is formed; in the latter case a neutral structure known asa complex is formed, in which the copper, as such, possesses a minimum of chemical activity.

are therefore normally able to chemically comblue with, or be adsorbed at the surface of the g'ang'ue minerals, the presence of such molecular group as is mentioned above causes these same ions to be withdrawn from solution into nonreacting complexes where they become relatively harmless, thus:

It is well known that in the blue solution formed, the copper is tied up in the complex ion '('Cu(NHa) 4) which is relatively stable and only slightly ionized as compared with copperchloride itself. Nevertheless, a slight dissociation of complex cation does occur, thus:

(Cu(NH3) 4) ++2Cu+++4NHa as proved by the fact that the Cu++ canbe precipitated by Has. Instead of using inorganicdipolar molecules such'as NHa in order to bind-up 7 their molecule certain groups capable of uniting the actually or potentially activating cations, this invention is based upon the principle that dissociated metallic ions in solution in the pulp liquid, or adsorbed on the ganguelparticles, may

be caused to form much mofe stable, undissociable, water soluble or insoluble, but hydrophilic, inner complexes with specific organic chemicals, which will be set forth hereinafter, which are added to the pulp.

,These specific organic reagents mustpossessin with metals through the replacement ofv the acidic hydrogen, the metalin the resultant compounds being held in position by a primary or While-Cu, or other metallic ions, in solution this electro-valence, and, on the other hand, other groups being capable of combining with metals through the coordination bond, that is, without thereplacement of hydrogen. If these two functional groups are both attached to one single organic radical in theproper relative position such as to satisfy the Baeyer straintheory, acyclic structure will be formed which is known as an inner complex or chelate compound. The metal atom in these four, five or six membered rings is most frequently attached to a nitrogen, oxygen or a sulfur atom by electrovalence (salt formation), and it completes the cycle through coordinate valence linking it to another functional group containing nitrogen, oxygen or sulfur.

The conception inner complex may b defined for the purpose of this specification as a cyclic. chemical structure containingan inorganic cation-(o1 positively charged metal ion) that is bound simultaneously to severalatoms ina single organic molecule, on the one hand by means of the ordinary valence bonds, or electron exchange on the other hand through the action of an But, if instead of acetic acid, the amino derivative of the same (amino-acetic acid or glycocoll) is used, an inner complex results from the combination of the cation and the amino acid (copper glycine) thus:

zcmNrnooo- 211+ Cu"- This compound (complex copper glyconate) is soluble, but the copper atom is bound in such a complete'mann'er that no more dissociation is possible. As -a result, no measurable free Cu++ ions can be detected in the solution, no reaction occurs with HaS, carbonates, caustic or even ammonia, and the solution of the complex shows practically no electrical conductivity;

This class of organic chemicals outlined above is used as reagents in inorganic analysis (especially in the spot test method),'for they are or may be rendered specific toward certain cations. Some of them have also been proposed as flotation collectors, although mostly without a complete understanding of the fundamentals involved; for this last purpose they must form insoluble, hydrophobic coatings, i. e. an oriented water-repellent film, on the surface of the mineral particle. But, in order to fulfill the aim of disactivating or depressing the gangue by removal of the free or adsorbed metallic ions acting as actual or potential activators according to the present invention, the formed inner complexes or chelate compounds with said cations have to be water soluble or hydrophilic.

Thus, the present invention discloses the use of organic compound capable of forming specific soluble or hydrophilic inner complexes with metallic ions in solution or adsorbed on the mineral particles, and-thereby preventing such' ions from exerting an activating influence on the gangue.

In addition to these general conditions required to form a cyclic chelate compound, the latter must be water soluble or hydrophilic'in order to fulfill the desiredpurpose. The structural fea-v tures promoting water solubility-or hydrophilic character for an organic compound are not yet completely understood (Refer, in H. Gilman, fOrgaplc Chemistry, John Wiley and Sons, Inc., New

York, N.;Y., 1938, the chapter: Constitution and physical "properties of organic compounds, by

Wallace R. Brode and John A. Leermakers). Nevertheless, the following facts may help to clarify the relation between constitution and water aflinity:

' Water solubility is not merely a physical, but rather a chemical phenomenon, which depends upon the ability 'of the soluteto bind dipolar water molecules (dipole moment of water ,!L=1.84'10 1B e. s.). Hydrophily, .as will .be shown, is closely relatedto solubility.

,Thelsimilarity' between the dissoivee material,

and the molecules of the solvent appear to be very important to the whole problem of solution,

Because the combining power of the metal atom in a chelate compound is saturated by bonds and complex linkages with several atoms of the same organic molecule, inner complexes are mostly non-electrolytes and the attraction of. water molecules (consequently, the hydrationand the solubility) is inhibited as well as the dissociation. Thus, anthranilic acid (o-aminobenzoic acid) has asolubility of 230 grs. in 100 cc. of water at 107.8 0., while its cobalt complex is practically insoluble in boiling water.

Therefore, in addition to the structure required for the formation of a chelatecompound (i. e., salt-forming group, complex-forming group and steric disposition allowing the closure-of a four-, fiveor six-membered ring), the organic depressing reagents, in order to yield solubl or hydrophilic inner tional features which will promote the hydration,

-i. e. groups tending to bind water molecules (or an electric field due to distortion having the same effect).

Groups which promote afllnity towards water molecules for an organic compound are, for ,example, the amino, the carboxyl functions. (In the alkanes series, the amino group is generally more active than the carboxyl group, and the latter more active than thehydroxyl group.) But,

in addition to the presence of these hydration centers, two other factors play an important role: (a) the balance between the polar (lyophilic) function and the non-polar (lyophobic) hydrocarbon radical; (b) the configuration of the molecule. i

As a, broad rule,, 'itmay be pointed out that each of the followingstructural features will impart water soiubilityjprhydrophily to an inner complex: 5 1.

Firstly, the chelate "compound (aliphatic or aromatic) must have at least one free group containing one or both of the elements composing the water molecule (0 and H). This is particularly the case for the hydroxyand carboxyl-group, and, to a lesser extent, of the aldehyde and carbonyl-group. It shall be noted that the replacement. of the oxygen atom by sulfur will result complexes, ought to have addiin the formation of less soluble or insoluble complexes. As already pointed out, the length of the individual carbon chains of the radical in the aliphatic series must not overbalance the lyophilic function (i. e. contain, for example, less than '7 carbon atoms for a. hydroxyl group, and less than 8 carbon atoms for a carboxyl group in the nalkane series).

The configuration plays an important role, par- The above observations concerning structure hold true for all the following points.

Secondly, the chelate compounds containing free inorganic acid radicals like sul1o-, phospho-, arseno-radicals, and the hydrochlorides of arcmatic bases, etc., are generally soluble or hydrophilic. This is particularly the case for the aromatic sulfonates. 1

Thirdly, the trivalent nitrogen atom of amino groups (and heterocyclic compounds) promotes the solubility to an even higher degree than the hydroxyl function.

Thus, n-butane is slightly soluble in water (15 cc. at 17 C. and 772 mm..pressure in 100 gr. water); 7.9 gr. n-butyl alcohol (butanol 1) dissolve in 100 gr. water at 20 C.; 5.62 gr. nbutyric acid dissolve in '100 gr. water at 1 0.; whil'n-butylamine is completely miscible with water (solubility Acetic acid is completely miscible with water. Esterification of the carboxyl group gives insoluble compounds. But the introduction of an amino-group in an acetic ester brings back the solubility. :Substitution of the hydrogen atoms of the NHz group decreases the It should be noted that, in a-amino acids, esterification of the carboxyl group increases the solubility. This is due to the fact that, in the free acids, the ionizable hydrogen is linked by a secondary valence to the nitrogen (of the amino function), thus blocking a coordination center for water molecules. Esterification liberates the amino group.

EXAMPLE Aminoacetic acid Aminoacetic acid ethyl ester CH2OOO1 (1112000055 HzN Hm Soluble 1 gr. in 4.5 grs. water Misciblc with water A heterocyclic nitrogen atom, even acting as a center of coordination (complex forming group) yields soluble complexes if it belongs to a single ring (pyridine radical). Thus, a-picolinic acid forms colored, soluble iron (Fe++) complexes, (as well as a silver complex), while the complexes of 8-oxyquinoline or a-quinaldinic acid are generally insoluble.

Fourthly, if the lyophilic groups as mentioned above, especially the carboxyl and amino (primary, secondary or tertiary) functions, acting at the same time as salt-forming and complexforming functions, overbalance the'radical (i. e., the individual carbon chains) in a compound of the aliphatic series, the complex will be soluble even if no supplemental free lyophilic group is present. This is the case when no more than 4 carbon atoms are attached to the reactive grouping.

As shown above, the amino group (primary, secondary or tertiary) and the carboxyl group are very powerful solubility-promoting functions.

Solubility ,Simple m al) P 0n the other hand, the hydrogen of the carboxyl P but Increases 191115 P p y in a group is easily'dissociable (salt-forming group), acids. while the nitrogen of the amino function and EXAMPLE 0! hetercyclic N-compounds is one of the most (a) active centers of coordination (complex-forming group). Therefore, organic compounds with one solubijity Dipole mo amino nitrogen in alpha or beta position to one o vo Formula m g M 1 carboxyl group, and at least one additional amino X 0' or carboxyl group to impart water solubility, i. e. F l C H NE E +1 31 polycarboxylic amino acids, monocarboxylic polyfiidiiiliiiiiiitj .IIIII? (data-$111 I 81.5 +0194 amino c s, and p carboxylic po y mi o ac ds. Trim-lemme in which one amino group is in 1 or 2 position to one carboxyl function, will yield soluble or Compound Formula Solubility Amino acetic acid 11 0-0 0 OH 1 gr. in 4.3 gr./l5 O.

Acetic acid monoethylamine HC-C 0 OH Very soluble.

NH(C3H5) Acetic acid dietbylamine HC--C 0 OH Hygroseopic. N(C2Hs)z a-Amino ceprolc acid NH; 1 gr. in 48.8 sip 12 c.

CHa(CHi)2 JHCO0E Caproic acid u-monomethylaminc CH:(CH2)2CHC 0 0H 1 gr. in 9.8 gin/13 C.

NH(CH:)

hydrophilic inner complexes, and thus are excellent organic flotation depressants, through the binding of gangue activating cations into cyclic chelates.

These organic depressants, which are the 5 specific subject of the present invention, have the following structural characteristics:

acid derivative (sodium salt) of ethylene diamine is manufactured by the General lDyestufic Corporation, 435 Hudson Street, New York, N. Y.,

Class of Salt-form- Complex-form- Example oi Hydrophilic compounds ing group ing group reactive grouping group Examples Monoamino poly- CO0H -NH,, =NH, 0 H COOH Aspartic acid (aminosuccinic acid) carboxylic acids. EN g B H0zOOH1OH(NH )COnH H, H Glutamic acid -C('3 HO:C(CH1):CH(NH2)CO2H H NH:

g Iminodiacetlc acid HN- C=O CHSC 01H \CH:CO|H I] Ohelidamic acid (4 hydroxy Mine-2.6 C-N= dicarboxyllc we?" 6 OH g t i H H H C H HO C- CO H H0 (1- -00 C-N-(L 2 a N N OH Pyridine dicarboxylic acids 2.3 quinolinic 2.4 lutidinie-; I 2.6 dipicolinic-;H2.5 isocinchomeric acids N=J 0 HO- HO C-COOB;

- HO C-GOOH Polyamino mono- COOH NH:, =NH H -NH;, =NH Ornithlne a a diaminovaieric acid) carboxylic acids. EN 1 E mNwri-nonmncoom 11,1 1 6H Arginine (a amino-6-guanid lvnleiic acid) H H HaNC(NH)NI.( :)|CH&H:)C0::H ouamcmo acetic age -N -C=0 HaIi- O(=NH)NH -C 00 B:

Polyamino oiy- --CO0H -NH1, =NH, O H -NH: =NH, Uroxanic acid carboxylic acids. EN g 1 EN, (10011 coon f H HzNOOHN-l-eNHO ONE,"

H 0 K ureuine a 0 0H 1 0H H|N0|H =CH-CH(NH;)CO;H NH! 7 v -O 0 OH =NH, NE E: =NH, N Ethylene diamine tetra acetic acid i 4} COOH HOICHIG r H CHzCOrH -c=0 g 7 H 4 HOaHaC 1 I l CHzCOaH It should also be noted that, in addition to osand marketed under the trade name Nullapon the proper functional groups, the compounds belonging to the aliphatic series do not have individual non-polar radicals any longer than 4 carbons.

As is Well known, most of these aliphatic 7 amino-acids are present (decomposition products of proteins) in the hydrolysis liquor of vegetal matters (soy-bean, wheat-, sugar 'cane-, beet juices, etc.) and can be extracted therefrom.

amounts of approximately 0.05 kg. per metric ton of ore, and to condition (agitate) for several minutes.

Dispersants and pH regulators (sodium silicate, sodium carbonate, caustic, hydrofiuosilic acid, sulfuric acid) are then fed as Certain polyamlno polycarboxylic acids are arm 75 usual and finally the flotation is performed with 11 a properly selected collector such as a fatty acid emulsion. A frother may be added, if required.

f As the depressing effect of the organic compound is sufliciently strong, a paraflin oil (gas oil, kerosene, etc.) can be used in addition to the chemically active collector, reducing substantially the amount of the latter. This is a further advantage of the process.

In the following schematic tests, the collecting emulsion was chosen so as to be very unselective byitself, in order to emphasize the depressing action of the new reagents. This is evidently bad flotation practice, but a convenient experimental procedure. Synthetic ores" (i. e. mixtures of more or less pure minerals) were used, and the flotation performed on 30-grs. samples in a. small laboratory cell (capacity: 150 00.), the dilution being 1:5 (distilled water).

Tests I to V were run with a ---65 mesh mixture containing malachite, 30% limestoneand 60% quartz (3.77-3.80% C11). The collecting emulsion had the following composition:

The recovery is good, due to the strong collecting properties of the emulsiornbut the grade of the concentrate is naturally low, asa result of its lack of selectivity. Th limestone and fine quartz Comments The grade of concentrate is only' slightly better than in the foregoing test, as the depressant was added after the collector, and therefore could not properly react.

Tssr III Reagents 0.15 cc. 1% solution Nullapon 3---- Cond.? min. 0.1 cc. 10% soda ash solutions This test shows the high selectivity obtainable by the proper use of an organic complexing depressant. The grade of concentrate rose from 7.21% to 25%, while th tailings dropped from 0.37% to 0.18%.

Tnsr IV Reagents 0.15 cc. 1% solution glutamic acid Cond. 3 min. 0.1 00'. 10% soda ash so1ution sodlum s1h cate 33 B 0.2 cc. 10% vol. sodium silicate Cond. 4 min. 1.0 cc. emulsion C0nd1t. 2 mm. 38 B a (1) droplet frlother B-23 (Amer. Cyanamid Co.) 1.0 emulsion Cond 2 min.

- emu 5111 40 1 droplet frother 13-23 Results 0.3 cc. emulsion W h P R Results eig t er cent ecov. Products gm Cu Grs. Cu per cent W I h P Products eig t, er cent GT8 Cu Recov.

s. o 0011c 14. 7a 7.21 1.062 95.08 1 gr H per cent Tails 14. 84 0. 37 .055

Cone 5.24 19.70 1. 032 93.31 Calc.l1eads 22.51 a 78 1.111 T i 23.86 0.31 .014

Cale. heads 29. 09 1. 106 Comments Comments The grade of concentrate is 19.70% versus 7.21; the tailings are slightly better than in Test I, due to the use of an organic complexing departicles were floated. pressant TEST II Tasr V Reagents Reagents 0.1 cc. 10% soda ash solution..- 0.15 cc. solution d1. Aspartic 0.2 00. 10% vol. sodium silicate Cond. 4 min. acid Cond. 3 min.

38 B 0.1 cc. 10% soda ash solution 1.0 cc. emulsion Cond. 2 min. 0.2 cc. 10% vol. sodium silicate Cond. 4 min. 0.15 cc. 1% solution Nullapon B (Ethyl- 38 B ene diamine tetra acetic acid) Cond. 3 min. 1.0 cc. emulsion Cond. 2 min. 1 droplet frother B-23 5 1 droplet frother 3-23 0.3 cc. emulsion 0.3 cc. emulsion Results Results Products W35? a? Grs. Cu g f 'g Products WEE? bi Grs. Cu zsg Conc 12. 35 1. 053 94.18 00110 7.61 13.80 1. 050 04 45 Ta- 11. 23 0.38 .065 Tails 21. 0.28 .001

Cale. heads 29. 58 3. 78 l. 118 Cale. heads 29. 36 1. 111

Comments The grade of concentrate is 13.80 versus 7.21; better tailings are also obtained.

The next two tests were made with a 65 mesh mixture containing gr. rhodochrosite (manga- 5 nese carbonate) and 25 gr. of silica sand for each 30 gr. head sample.

Tnsrr VI Reagents 0.25 cc. 10% soda ash solution Cond.4 min. 0.10 cc. 10% vol. sodium silicate 38 B Cond.3min. 0.10 cc. 5% monopolsoap (sodium salt of highly sulfonated castor oil) 0.05 cc. oleic acid cond'zmm' 0.03 00. kerosene; 1 droplet frother 3-23 Results Products WEE? i fi Grs.Mn 32: 2

cont 12.38 10.2 1.2027 04.00 Tails 17.14 0.03 0. 079a Cale. heads .29. 52 4.54 1. 3425 Comments Good recovery, but the tailings are relatively high and the concentrate is contaminated with fine silica.

Tssr VII Reagents 0.1 cc. 1% solution of Nullapon B Cond. 3 min. 0.25 cc. 10% soda ash solution Cond. 4 min. 0.10 00. 10% vol. sodium silicate 38 B Cond.3min. 0.10 cc. 5% Monopolsoap 0.06 cc. oleic acid 0.03 cc. kerosene cond'2mm' 1 droplet frother B-23 Results Products gg i g Grs.Mn 2:32}

Cone 7.22 17.19 1.2411 94.55 Tails 22. 37 0.32 0.0715 Calaheads 29.59 4.44 1.8126

Comments Higher grade of concentrate (17.19% versus 10.2%) and better tailings, due to the use of an organic complexing depressant.

The next test was run with a 30-gr. sample containing 22.5 grs. of a mixture of 65% silica and 35% limestone, 2.5 grs. chalcosite (with some as chalcopyrlte), and 5 g'rs. galena. In this case,

an excess of the organic complexing depressant was added, in order to float selectively the lead sulfide from the copper mineral.

Tssr V111 Reagents 1.0 cc. 1% solution of Glutamic acid- Cond. 5 min. 0.15 cc. 10% soda ash solution 0.1 cc. 10% vol. sodium silicate Cond.2min.

38 B 0.2 cc. 1% sodium ethyl xanthate. 1 droplet frother 3-23.

Results Products g P ag Grs.Cu 553" 0 T335 it it 2.92% .6... Cale. heads 29. 49 0. 114 1. 803

The following example will further illustrate how the said invention may be carried out in practice, but the invention is not restricted to this example.

EXAMPLE A deslimed (+10 mu) oxide copper ore from Miami (Arizona) had been floated with ethyl xanthate, oleic acid, soda ash, sodium silicate and cyanide as specific depressant (following the Earl Fisher process). The results of the roughing operation werereported as follows by the operators:

Product Weight gg $9 eg 5312;

lstconc--- 13.9 7.1 0.9809 00.00 1:27 211d 00110.-.- 14.7 1.2 0.1704 11.80 1:0.8 3rd cone"--- 18.5 0.0 46 0.1203 v 8.05 Tails 52.0 0.40 0.2110 14.15 Heads 100.0 1.50 1.4952 100.00

The same are was floated without cyanide, but with an added amount 01' ethylene diamine tetra acetic acid (Nullapon B") as follows:

1000 grs. ore 65 mesh were deslimed at 10 microns, yielding 670 grs. of a sand product with 1.575% Cu. These sands were floated as follows in a laboratory Fagergreen cell:

Nullapon B, 2% solution, 1.0 cc.. Cond. 3min. Soda ash, 10% solution, 2.0 cc Silicate 38 B., 10% vol., 1.0 cc Sodium ethyl xanthate, 1% solution, 1.5 cc. Alkanol S. A., 1% (emulsifier), 0.5 cc. Oleic acid, 0.3 cc.

Parafiln 011, 0.1 cc.

Kerosene, 0.1 cc.

The results are tabulated below:

Product Weight $3 2 35 gg" Rea. per cent Ratio of c0110,

12. 31. 84 4. 1a. 40 17. 1%} 5 a. 230 14. 85 4. 28 0. 536 see. 10 0. a4 2. 002

Cond. 5 min. I

The 3rd concentrate can be considered as a contrate and 1.0% in the tails, thus raising the final recovery to 78.2%.

While in the norma flotation a concentrate with 7.1% Cu (Rec. 66.0%) is obtained, the ratio being 1:4.7, the flotation following the present invention yields a product with 23.5% Cu (Rec. 73.6%). The tailings are 0.46 versus 0.34, and the middlings of the operation first reported are lower than the heads,

Comparison of these results shows that the ratio of concentration is considerably raised by conditioning the pulp with a polyamino polycarboxylic acid.

Therefore, the use, according to the present invention, of organic reagents accomplishing the purpose of gangue depression through complexing detrimental cations into a water soluble or hydrophilic chelate compound constitutes a marked advance in the art of froth flotation, and is highly advantageous in improving the selectivity of the collectors, thus improving the grade of concentrate.

What is claimed is:

1. In the concentration by froth flotation oi non-sulfide ores, which includes the subjecting of such material when finely ground to flotation in the presence of an emulsion of mineral oil and fatty acid stabilized by a wetting agent as collector and by the addition of usual modifiers, the step of adding first to the pulp an amount of the order of 0.05 kg'. per metric ton of a noncollecting organic compound containing one amino nitrogen in alpha or beta (1 or 2) position to one carboxyl group and having the following general schematic formula:

o (Lt-la (Lila-R H811: Ht s:

where R is a substituted organic aliphatic, aromatic or heterocyclic radical with at least one carboxyl group or one amino nitrogen; said organic compound being adapted to react with the gangue activating cations of the pulp to yield a water soluble or hydrophilic chelate compound having the schematic general formula:

where Me is a metal atom (monovalent) replacing the hydrogen of the carboxyl group by electron exchange and linked to the negative amino nitrogen by the coordination bond (dative bond), while the free carboxylor amino-function or functions attached to R are imparting water solubility to the chelate compounds.

2. The process as claimed in claim 1, where the depressing organic compounds are polyvalent amino acids extracted from protein-rich natural hydrolytes.

3. The process as claimed in claim 1, where the depressing organic compounds are polyvalent amino acids extracted from protein-rich natural hydrolytes.

4. The process as claimed in claim 1, where the depressing organic compound is a polyamino polycarboxylic acid corresponding to the general formula:

Ac Ac H H /N-RN AcN--R-NAc Ac Ac where R is a lower alkylene radical and Ac the radical of an aliphatic organic acid with less than 9 carbon atoms in the chain.

GREGOIRE GUTZEIT.