This invention concerns compositions useful as collectors for the recovery of metal-containing sulfide minerals, sulfidized metal-containing oxide minerals, metal-containing oxide minerals, and metals occurring in the metallic state, all four mineral groups referred to herein as metal-containing minerals, from ores by froth 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 is separated from other finely divided solids, e.g., clays and other like materials present in the ore, by introducing a gas (or providing a gas in situ) in the liquid to produce a frothy mass containing certain of the solids on the top of the liquid, and leaving suspended (unfrothed) other solid components of the ore. Flotation is based on the principle that introducing a gas into a liquid containing solid particles of different mater- ials 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, these particles rise to the top of the liquid to form a froth.

Various flotation agents have been admixed with the suspension to improve the frothing process.

Such added agents are classed according to the function to be performed: collectors, such as xanthates, thio- nocarbamates and the like; frothers, which facilitate the forming of a stable froth, e.g., natural oils such as pine oil and eucalyptus oil; modifiers, such as activators, e.g., copper sulfate to induce flotation in the presence of a collector; depressants, e.g., sodium cyanide, which tend to prevent a collector from func¬ tioning as such on a mineral which it is desired to retain in the liquid, and thereby discourage a sub¬ stance from being carried up and forming a part of the froth; pH regulators to produce optimum metallurgical results, e.g., lime, soda ash; and the like.

An understanding of the phenomena which makes flotation a particularly valuable industrial operation is not essential to the practice of this invention. The phenomena which render flotation a particularly valuable industrial operation 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 the one hand, the gas on the other. The specific additives used in a flotation operation are selected according to the nature of the ore, the mineral(s) sought to be recovered and the other addi¬ tives which are to be used in combination therewith.

Flotation is employed in a number of mineral separation processes including the selective separation of such metal-containing minerals as those containing copper, zinc, lead, nickel, molybdenum, and other metals from iron-containing sulfide minerals, e.g. pyrite and pyrrhotite.

Among collectors commonly used for the recovery of metal-containing sulfide minerals or sul¬ fidized metal-containing oxide minerals are xanthates, dithiophosphates, and thionocarbamates.

The conversion of metal-containing sulfide minerals or sulfidized metal-containing oxide minerals to the more useful pure metal state, is often achieved by smelting processes. Such smelting processes can result in the formation of volatile sulfur compounds. These volatile sulfur compounds are often released to the atomsphere through smokestacks, or are removed from such smokestacks by expensive and elaborate scrubbing equipment. Many nonferrous metal-containing sulfide minerals or metal-containing oxide minerals are formed naturally in the presence of iron-containing sulfide minerals, such as pyrite and pyrrhotite. When the iron- -containing sulfide minerals are recovered in flotation processes along with the nonferrous metal-containing sulfide minerals and sulfidized metal-containing oxide minerals, there is excess sulfur present which is released in the smelting processes. What is needed is a process for selectively recovering the nonferous metal- -containing sulfide minerals and sulfidized metal-con- taining oxide minerals without recovering the iron- -containing sulfide minerals such as pyrite and pyrr¬ hotite.

Of the commercial collectors, the xanthates, thionocarbamates, and dithiophosphates do not selec¬ tively recover nonferrous metal-containing sulfide minerals in the presence of iron-containing sulfide minerals. On the contrary, such collectors collect and recover all metal-containing sulfide minerals. The mercaptan collectors have an environmentally undesirable order and are very slow kinetically in the flotation of metal-containing sulfide minerals. The disulfides and polysulfides, when used as collectors, give low recoveries with slow kinetics. Therefore, the mercaptans, disulfides, and poly¬ sulfides are not generally used commercially. Furthermore, the mercaptans, disulfides and poly- sulfides do not selectively recover nonferrous metal- -containing sulfide minerals in the presence of iron-containing sulfide minerals.

In view of the foregoing, what is needed is a flotation collector which will selectively recover, at relatively good recovery rates, a broad range of metal-containing minerals from ores in the presence of iron-containing sulfide minerals such as pyrite and pyrrhotite.

The present invention, in one aspect, is a collector composition which comprises:

(a) a compound of the formula:

wherein is

-N(R ) _a (H) _b where a + b equals 2,

-N=Y where Y is S, 0, a hydrocarbylene radical or a substituted hydrocarbylene radical,

≡N, or

-N cyclic ring where the cyclic ring is saturated or unsaturated and may contain additional hetero atoms, but must contain the N;

R 1 and R2 are independently a C, ₂₂ hydro- carbyl radical, a C- ₂₂ substituted hydrocarbyl radical, or a saturated or unsaturated heterocyclic ring;

0

II

R is {C} _y -(CH ₂ -) _p CHOH-) _m

where y + p + m = n, where n is an integer from 1 to 6, and y, p and m are independently 0 or an integer from 1 to 6, and each moiety can occur in a random sequence;

X is -S-, -0-, -N-R ³

0 0 R ³ 0

II II ! II

C-S- , -C-N- , or -C-0- ,

3 where R is hydrogen, a C., ₂₂ hydrocarbyl radical or a substituted C ₁ _ ₂₂ hydrocarbyl radical; and

(b) an alkyl thiocarbonate, a thionocar- bamate, a thiophosphate, a thiocarbanilide, a thio- phosphinate, a mercaptan, a xanthogen formate, a xanthic ester or mixture thereof.

In another aspect, the invention also con¬ cerns a process for recovering metal-containing sulfide minerals from an ore which comprises subjecting the ore, in the form of an aqueous pulp, to a froth flota¬ tion process in the presence of a flotating amount of a flotation collector under conditions such that the metal-containing minerals are. recovered in the froth.

The collector compositions of this invention are capable of floating a broad range of metal-contain¬ ing minerals. Furthermore, such collector compositions also give good recoveries and selectivity towards the desired metal-containing minerals. The novel collector composition of this invention often gives higher recov¬ eries, often with better grade, than can be achieved with the use of either collector component alone.

In a preferred process of the present inven¬ tion, the described collector composition is employed in a process for recovering metal-containing sulfide minerals on sulfidized metal-containing oxide minerals from an ore, which comprises subjecting the ore, in the form of an aqueous pulp, to a froth flotation process in the presence of a flotating amount of the collector composition at conditions sufficient to cause the

metal-containing sulfide mineral or sulfidized metal- containing oxide mineral particles to be driven to the air/bubble interface and recovered in the froth.

The collector composition of this invention results in a surprisingly high recovery of nonferrous metal-containing minerals and a higher selectivity toward such nonferrous metal-containing minerals when such metal-containing minerals are found in the presence of iron-containing sulfide minerals

Component (a) of the collector composition of this invention is a component of formula (I) above. Although not specifically set forth in formula (I), it should be understood that in aqueous medium of low pH, preferably acidic, component (a) can exist in the form of a salt. In this formula, R is advantageously (-CH,-) ,

-s P

or mixtures thereof where p + m + y = n, where n is an integer from 1 to 6, preferably 2 or 3. R 1 and each R2 are advantageously a _ ₂₂ hydrocarbyl radical or a

^G _l -22 ⁿ Ydrocarbyl radical substituted with one or more hydroxy, amino, phosphonyl, alkoxy, imino, carbamyl, carbonyl, thiocarbonyl, cyano, halo, ether, carboxyl, hydrocarbylthio, hydrocarbyloxy, hydrocarbylamino or hydrocarbylimino groups. If substituted, R 1 or R2 i•s advantageously substitued with one or more hydroxy, halo, amino, phosphonyl or alkoxy moiety. Q is pre- ferably -N(R 2) _a (H) _b where a + b equals 2.

More advantageously, the carbon atoms in R

2 . 1 and R total 6 or more with R preferably being a C ₂ -i4 hydrocarbyl, or a C ₂ , ₄ hydrocarbyl substituted with one or more hydroxy, amino, phosphonyl, or alkoxy

2 groups, more preferably a C ₄ ,, hydrocarbyl; and R preferably being a C-, ₆ alkyl, C. _g alkylcarbonyl or

C- g-substituted alkyl or alkylcarbonyl, more preferably a C, ₄ alkyl or C ₁ _ ₄ alkylcarbonyl or a C, ₆ alkyl or , ₆ alkylcarbonyl substituted with an amino, hydroxy or phosphonyl group, and most preferably a C, ₂ alkyl or C,_ ₂ alkylcarbonyl. In addition, R is preferably

(-CH ₂ -) _p or

more preferably (-CH ₂ -) ; n is preferably an integer from 1 to 4, most preferably 2 or 3; X is preferably -S-, -N '-R3, or -0-, more preferably -S- or -N'-R3, most preferably -S-; and R 3 i.s preferably hydrogen or C- ₁₄ hydrocarbyl, more preferably hydrogen or C, ... hydro¬ carbyl, most preferably hydrogen.

As described, the component (a) includes compounds such as —

the S-(omega-aminoalkyl) hydrocarbonthioates:

0

R ¹ -C-S _T CH Δ nNifR ² )i

(Hk,

II

the omega-(hydrocarbylthio)alkylamines and omega- (hydrocarbylthio)alkyl amides:

R ¹ -S CH ₂ ^N R ² ) _a ; < ^H >b

III the N-(hydrocarbyl)-alpha,omega-alkanediamines:

IV the N-(omega-aminoalkyl) hydrocarbon amides:

0

V the omega-(hydrocarbyloxy-)alkylamines:

R ¹ -O CH ₂ - _n N R ² ) _a

(H) _b

VI and the omega-aminoalkyl hydrocarbonoates:

0

R ¹ -CO CH ₂ ^ _n N R ² ) _a (H) _b

VII

wherein R 1, R , R 3, a, b and n are as hereinbefore defined. In formulas II—VII, when X is -S- or

0

II

-C-S-

R is preferably a C ₄ _ _1Q hydrocarbyl; when X is

0 R ³

II I

-N- or -C-N-

the total carbon content of the groups R 1 and R3 is preferably between 1 and 23, more prefer¬ ably 2 and 16, and most preferably 4 and 15; and when X is

0

II

-CO- or -0-

R is most preferably C _g ... hydrocarbyl.

Of the foregoing, the preferred component

(a) compound includes omega-(hydrocarbylthio)alkyl- amine, N-(hydrocarbyl)-alpha,omega-alkanediamine,

omega-(hydrocarbyloxy-)alkylamines, N-(omega-amino¬ alkyl)hydrocarbon amide, omega-(hydrocarbylthio)- alkylamide or mixtures thereof. More preferred com¬ ponent (a) compounds include omega-(hydrocarbylthio)- alkylamines, N-(hydrocarbyl)-alpha,omega-alkanediamines, N-(omega-aminoalkyl)hydrocarbon amides, omega-(hydrocar¬ bylthio)alkylamide or mixtures thereof. The most pre¬ ferred class of component (a) compounds are the omega- -(hydrocarbylthio)alkylamines and omega-(hydrocarbyl- thio)alkylamide. Especially preferred compounds are 2-(hexylthio)ethylamine and ethyl 2-(hexylthio)ethyl- amide.

The omega-(hydrocarbylthio)alkylamines of formula III can be prepared by the processes disclosed in Berazosky et al. , U.S. Patent 4,086,273; French

Patent 1,519,829; and Beilstein, 4, 4th Ed., 4th Supp., 1655 (1979).

The N-(omega-aminoalkyl) hydrocarbon amides of formula V can be prepared by the processes described in Fazio, U.S. Patent 4,326,067; Acta Polon Pharm, 19, 277 (1962); and Beilstein, 4, 4th Ed., 3rd Supp., 587 (1962).

The omega-(hydrocarbyloxy)alkylamines of formula VI can be prepared by the processes described in British Patent 869,409; and Hobbs, U.S. Patent 3,397,238.

The S-(omega-aminoalkyl) hydrocarbon thioates of formula II can be prepared by the processes described in Faye et al. , U.S. Patent 3,328,442; and Beilstein, 4, 4th Ed., 4th Supp., 1657 (1979).

The omega-aminoalkyl hydrocarbonoates of formula VII can be prepared by the process described in J. Am. Chem. Soc, 83, 4835 (1961); Beilstein, 4, 4th Ed., 4th Supp., 1413 (1979); and Beilstein, 4, 4th Ed., 4th Supp., 1785 (1979).

The N-(hydrocarbyl)-alpha,omega-alkanedi- amines of formula IV can be prepared by the process well-known in the art. One example is the process described in East German Patent 98,510.

The second component (b) of the collector composition of this invention is an alkyl thiocarbonate, a thionocarbamate, a thiocarbanilide, a thiophosphate, thiophosphinates, mercaptan, xanthogen formate, xanthic ester and mixtures thereof. Preferred second component (b) collectors are an alkyl thiocarbonate, a thionocar¬ bamate, a thiophosphate or mixtures thereof.

As used herein, the term "thiocarbonate" includes compounds which contain a thiocarbonyl moiety (-C=S) and one or more hydrocarbyl moieties wherein the hydrocarbyl moiety is of a hydrophobic character, preferably having at least 2 carbon atoms, so as to cause a metal-containing sulfide mineral or sulfidized metal-containing oxide mineral particles associated therewith to be driven to an air/bubble interface. Preferred thiocarbonates are the alkyl thiocarbonates represented by the structural formula:

z ²

IX wherein

4 is a C _1->20 , preferably C ₂ -16' more preferably C, _, alkyl group; Z 1 and Z2 are independently a sulfur or oxygen atom; and M is an alkali metal cation.

The compounds represented by formula IX include the alkyl thiocarbonates (both Z 1 and Z2 are oxy- gen), alkyl dithiocarbonates (Z 1=0, Z2=S) and the alkyl tnthiocarbonates (both Z 1 and Z2 are sulfur)

Examples of preferred alkyl monothio- carbonates include sodium ethyl monothiocarbonate, sodium isopropyl monothiocarbonate, sodium isobutyl monothiocarbonate, sodium amyl monothiocarbonate, potassium ethyl monothiocarbonate, potassium iso- propyl monothiocarbonate, potassium isobutyl mono¬ thiocarbonate, and potassium amyl monothiocarbon¬ ate. Preferred alkyl dithiocarbonates include potassium ethyl dithiocarbonate, sodium ethyl di- thiocarbonate, potassium amyl dithiocarbonate, sodium amyl dithiocarbonate, potassium isopropyl dithiocarbonate, sodium isopropyl dithiocarbonate, sodium sec-butyl dithiocarbonate, potassium sec- -butyl dithiocarbonate, sodium isobutyl dithio¬ carbonate, potassium isobutyl dithiocarbonate,

and the like. Examples of alkyl trithiocarbon¬ ates include sodium isobutyl trithiocarbonate and potassium isobutyl trithiocarbonate. It is often preferred to employ a mixture of an alkyl monothiocarbonate, alkyl dithiocarbonate and alkyl trithiocarbonate.

Preferred thionocarbamates correspond to the formula

(R ⁵ ) - -NN--C-Y

(H)

X wherein

R ,5" is independently a C-,_ _1Q , preferably a C. ₄ , more preferably a C, ₃ , alkyl group;

Y is -S —M+ or -OR6, wherein R6 is a

^C 2-1 ₀ ' P ^re f ^era blY ^{a C} 2- ₆ ' ^more preferably a C ₃ _ ₄ , alkyl group; c is the integer 1 or 2; and d is the integer 0 or 1, wherein c+d must equal 2.

Preferred thionocarbamates include dialkyl dithiocarbamates (c=2, d=0 and Y is S~M ) g and alkyl thionocarbamates (c=l, d=l and Y is -OR )

Examples of preferred dialkyl dithiocarbamates include methyl butyl dithiocarbamate, methyl iso- butyl dithiocarbamate, methyl sec-butyl dithiocar¬ bamate, methyl propyl dithiocarbamate, methyl iso-

propyl dithiocarbamate, ethyl butyl dithiocarba¬ mate, ethyl isobutyl dithiocarbamate, ethyl sec- -butyl dithiocarbamate, ethyl propyl dithiocarba¬ mate, and ethyl isopropyl dithiocarbamate. Exam- pies of preferred alkyl thionocarbamates include N-methyl butyl thionocarbamate, N-methyl isobutyl thionocarbamate, N-methyl sec-butyl thionocarbamate, N-methyl propyl thionocarbamate, N-methyl isopropyl thionocarbamate, N-ethyl butyl thionocarbamate, N-ethyl isobutyl thionocarbamate, N-ethyl sec-butyl thionocar¬ bamate, N-ethyl propyl thionocarbamate, and N-ethyl isopropyl thionocarbamate. Of the foregoing, N-ethyl isopropyl thionocarbamate and N-ethyl isobutyl thiono¬ carbamate are most preferred.

Thiophosphates useful herein generally cor¬ respond to the formula

XI wherein R 7 i.s independently hydrogen or a ^c -ι ₁₀ / pre¬ ferably ₂ _ ₈ , alkyl group or an aryl, preferably an aryl group having from 6-10 carbon atoms, most pre- ferably cresyl; Z is oxygen or sulfur; and M is an alkali metal cation.

Of such compounds, of formula XI, those preferably employed include the monoalkyl dithio- phosphates (one R 7 is hydrogen and the other R7 i.s a

^C l-10 ^alk y ^{1 and z} ^ ^{s s} ~)' dialkyl dithiophosphates

₇ -

(both R are C ₁ _ _1Q alkyl and Z is S ), dialkyl mono-

7 - thiophosphate (both R are a C-. _1Q alkyl and Z is 0 ), aanndd ddiiaryl dithiophosphate (both R '7 are aryl and Z is s ^" )

Examples of preferred monoalkyl dithiophos- phates include ethyl dithiophosphate, propyl dithio¬ phosphate, isopropyl dithiophosphate, butyl dithio¬ phosphate, sec-butyl dithiophosphate, and isobutyl dithiophosphate. Examples of dialkyl or diaryl dithio- phosphates include sodium diethyl dithiophosphate, sodium di-sec-butyl dithiophosphate, sodium diisobutyl dithiophosphate, sodium diisoamyl dithiophosphate and sodium dicresyl dithiophosphate. Preferred onothio- phosphates include sodium diethyl monothiophosphate, sodium di-sec-butyl monothiophosphate, sodium diisobutyl monothiophosphate, and sodium diisoamyl monothiophos¬ phate.

Thiocarbanilides (dialkyl thioureas) are represented by the general structural formula:

H

(R ₁₁ -N^ ₂ C=S

XII wherein R.,-, is individually H or a C. _g , preferably a C._ ₃ , hydrocarbyl.

Thiophosphinates are represented by the general structural formula:

wherein M ⁺ is as hereinbefore described and R. ₂ is independently an alkyl or aryl group, preferably an alkyl group having from 1 to 12, more preferably an alkyl group having from 1 to 8 carbon atoms. Most preferably, each R-, ₂ is isobutyl.

Mercaptan collectors are preferably alkyl mercaptans represented by the general struc¬ tural formula:

R ₁₃ -S-H XIV wherein R-, ₃ is an alkyl group, preferably an alkyl group having at least 10, more preferably from 10 to 16, carbon atoms.

Xanthogen formates are represented by the general structural formula:

XV wherein R ₁₄ is an alkyl group having from 1 to 7, preferably from 2 to 6 carbon atoms and R ₁₅ is an alkyl group having 1 to 6, preferably 2 to 4, more preferably 2 or 3, carbon atoms.

Xanthic esters are preferably compounds of the general structural formula:

XVI wherein R., _g is an allyl group having from 2 to 7 7 ccaarrbboonn aattoommss,, aanndd RR ₁₁₇₇ is an alkyl group having from 1 to 7 carbon atoms

Preferred compounds for use as compo¬ nent (b) herein are the thiocarbonates, thionocar- bamates and the thiophosphates due to the surpris¬ ingly high recoveries and selectivities towards metal-containing minerals which can be achieved!

Hydrocarbon means herein an organic compound containing carbon and hydrogen atoms. The term hydrocarbon includes the following organic com¬ pounds: alkanes, alkenes, alkynes, cycloalkanes, cyclo- alkenes, cycloalkynes, aromatics, aliphatic and cyclo- aliphatic aralkanes and alkyl-substituted aromatics.

Aliphatic refers herein to straight and branched-chain, and saturated and unsaturated, hydrocarbon compounds, that is, alkanes, alkenes or alkynes. Cycloaliphatic refers herein to satu¬ rated and unsaturated cyclic hydrocarbons, that is, cycloalkenes and cycloalkanes.

Cycloalkane refers to an alkane containing one, two, three or more cyclic rings. Cycloalkene refers to mono-, di- and polycylic groups containing one or more double bonds.

Hydrocarbyl means herein an organic radical containing carbon and hydrogen atoms. The term hydrocarbyl includes the following organic radicals: alkyl, alkenyl, alkynyl, cycloalkyl, cyclo- alkenyl, aryl, aliphatic and cycloaliphatic aralkyl and alkaryl. The term aryl refers herein to biaryl, biphenylyl, phenyl, naphthyl, phenanthrenyl, anthra- cenyl and two aryl groups bridged by an alkylene group. Alkaryl refers herein to an alkyl-, alkenyl- or alkynyl-substituted aryl substituent, wherein aryl is as defined hereinbefore. Aralkyl means herein an alkyl group, wherein aryl is as defined hereinbefore.

^C l-20 ^{a k} yl includes straight and branched- chain methyl, ethyl, propyl, butyl, pentyl, hexyl, neptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl and eicosyl groups.

Halo means herein a chloro, bromo, or iodo group.

Hydrocarbylene means herein an organic radical containing carbon and hydrogen atoms which must be attached to the nitrogen atom by a double bond. The term hydrocarbylene includes the following organic compounds alkenyl, cycloalkenyl and aralkylene where aryl is defined as before.

A heterocyclic ring means herein both satur¬ ated and unsaturated heterocyclic rings, including an -N-cyclic ring. The heterocyclic ring may include one or more N, 0 or S atoms. Examples of suitable hetero- cyclic rings are pyridine, pyrazole, furan, thiophene,

indole, benzofuran, benzothiophene, quinoline, iso uino- line, coumarin, carbazole, acridine, imidazole, oxazole, thiazole, pyridazine, pyrimidine, pyrazine, purine, ethylenimine, oxirane, azetidine, oxetane, thiethane, pyrrole, pyrrolidine, tetrahydrofuran, isoxazole, piperidine, azepine and others.

The composition of the present invention is prepared using sufficient amounts of component (a) and component (b) to prepare an effective collector for metal-containing minerals from ores in a froth flota¬ tion process. The amounts of each component most advantageously employed in preparing the composition will vary depending on the specific components (a) and (b) employed, the specific ore being treated and the desired rates of recovery and selectivity. The compo¬ sition preferably comprises from about 10 to about 90, more preferably from 20 to 80, percent by weight, of component (a), and from about 10 to about 90, more preferably from 20 to 80, percent by weight, of compo- nent (b). The composition of this invention even more preferably comprises from about 30 to about 70 percent by weight of component (a) and from about 30 to about 70 percent by weight of component (b). Within these compositional limitations, the amount of components (a) and (b) are selected such that the recovery of metal- -containing minerals in a froth flotation process is higher than either component could recover at the same weight dosage.

A particularly preferred composition of the present invention comprises (a) an omega-(hydrocarbyl¬ thio)alkylamine, N-(hydrocarbyl)-alpha,omega-alkanedi- amine, N-(omega-aminoalkyl)hydrocarbon amide, omega- (hydrocarbylthio)alkylamide or mixtures thereof; and

(b) an alkyl thiocarbonate which comprises an alkyl monothiocarbonate, alkyl di hiocarbonate or alkyl tri¬ thiocarbonate.

The process of this invention is useful for the recovery by froth flotation of metal-containing minerals from ores. An ore refers herein to the metal as it is taken out of the ground and includes the desired metal-containing minerals in admixture with the gangue. Gangue refers herein to that portion of the material which is of little or no value and needs to be separated from the desired metal-containing minerals.

The collector composition of this invention is preferably employed in the recovery, in a froth flotation process, of metal-containing minerals In a more preferred embodiment of this invention minerals containing copper, nickel, lead, zinc, or molybdenum are recovered. In an even more preferred embodiment, minerals containing copper are recovered.

Ores for which these compounds are useful include sulfide mineral ores containing copper, zinc, molybdenum, cobalt, nickel, lead, arsenic, silver, chromium, gold, platinum, uranium, and mixtures thereof. Examples of metal-containing sulfide minerals which may be concentrated by froth flotation using the process of this invention include copper-bearing minerals such as, for example, covellite (CuS), chalcocite (Cu ₂ S), chalco- pyrite (CuFeS ₂ ), valleriite (Cu ₂ Fe ₄ S ₇ or Cu ₃ Fe ₄ S ₇ ), bornite (Cu ₅ FeS ₄ ), cubanite (Cu ₂ SFe ₄ S ₅ ), enargite [Cu ₃ (As ₁ Sb)S ₄ ] , tetrahedrite (Cu ₃ SbS ₂ ), tennantite (Cu ₁₂ As ₄ S ₁₃ ), brochantite [Cu ₄ (0H)gS0 ₄ ], antlerite

[Cu ₃ S0 ₄ (OH) ₄ ] , famatinite (Cu ₃ (SbAs)S ₄ ), and bournonite

(PbCuSbS-); lead-bearing minerals such as, for example, galena (PbS); antimony-bearing minerals such as, for example, stibnite (Sb ₂ S ₃ ); zinc-bearing minerals such as, for example, sphalerite (ZnS); silver-bearing minerals such as, for example, stephanite (Ag ₅ SbS ₄ ) and argentite (Ag ₂ S); chromium-bearing minerals such as, for example, daubreelite (FeSCrS ₃ ); nickel-bearing minerals such as, for example, pentlandite [(FeNi)Sg]; molybdenum-bearing minerals such as, for example, molybdenite (MoS ₂ ); and platinum- and palladium-bearing minerals such as, for example, cooperite [Pt(AsS) ₂ ]. Preferred metal-containing sulfide minerals include molybdenite (MoS ₂ ), chalcopyrite (CuFeS ₂ ), galena (PBS), sphalerite (ZnS), bornite (Cu ₅ FeS ₄ ), and pent- landite [(FeNi) _g SgJ.

Sulfidized metal-containing oxide minerals are minerals which are treated with a sulfidization chemical, so as to give such minerals sulfide mineral characteristics, so the minerals can be recovered in froth flotation using collectors which recover sulfide minerals. Sulfidization results in oxide minerals having sulfide mineral characteristics. Oxide minerals are sulfidized by contact with compounds which react with the minerals to form a sulfur bond or affinity. Such methods are well-known in the art. Such compounds include sodium hydrosulfide, sulfuric acid and related sulfur containing salts such as sodium sulfide.

Sulfidized metal-containing oxide minerals and oxide minerals for which this process is useful include oxide minerals containing copper, aluminum, iron, titanium, magnesium, chromium, tungsten, moly¬ bdenum, manganese, tin,, uranium, and mixtures thereof.

Examples of metal-containing oxide minerals which may be concentrated by froth flotation using the process of this invention include copper-bearing minerals, such as cuprite (Oi O), tenorite (CuO), malachite [Cu ₂ (OH) ₂ C0 ₃ ] , azurite [Cu ₃ (OH) ₂ (C0 ₃ ) ₂ ] , atacamite [Cu ₂ Cl(OH) ₃ ], chrysocolla (CuSi0 ₃ ); aluminum-bearing minerals, such as corundum; zinc-containing minerals, such as zincite (ZnO) and smithsonite (ZnC0 ₃ ); tungsten-bearing minerals such as wolframite [(Fe,Mn)W0 ₄ ] ; nickel-bearing minerals such as bunsenite (NiO); molybdenum-bearing minerals such as wulfenite (PbMo0 ₄ ) and powellite (CaMo0 ₄ ); iron-containing minerals, such as hematite and magnetite; chromium-containing minerals, such as chromite (FeOCr ₂ 0 ₃ ), iron- and titanium-containing ores, such as ilmenite; magnesium- and aluminum-containing minerals, such as spinel; iron-chromium-containing minerals, such as chromite; titanium-containing minerals such as rutile; manganese-containing minerals, such as pyrolusite; tin- containing minerals, such as cassiterite; and uranium- containing minerals, such as uraninite; and uranium- bearing minerals, such as, for example, pitchblende [U ₂ 0 ₅ (U ₃ 0g)] and gummite (U0 ₃ nH ₂ 0).

Other metal-containing minerals for which this process is useful include gold-bearing minerals, such as sylvanite (AuAgTe ₂ ) and calaverite (AuTe); platinum- and palladium-bearing minerals, such as sperrylite (PtAs ₂ ); and silver-bearing minerals, such as hessite (AgTe ₂ ). Also included are metals which occur in a metallic state, e.g., gold, silver and copper.

The collector compositions of this invention can be used in any concentration which gives the desired

recovery of the desired minerals. In particular, the concentration used is dependent upon the particular minerals to be recovered, the grade of the ore to be subjected to the froth flotation process, the desired quality of the minerals to be recovered, and the par¬ ticular mineral which is being recovered. Preferably, the collector compositions of this invention are used in concentrations of 5 grams (g) to 1000 g per metric ton of ore, more preferably between about 10 g and 200 g of collector per metric ton of ore to be subjected to froth flotation. In general, to obtain optimum syner- gistic behavior, it is most advantageous to begin at low dosage levels and increase the dosage level until the desired effect is achieved. Synergism is defined herein as when the measured result of a blend of two or more components exceeds the weighted average results of each component when used alone. This term also implies that the results are compared under the condition that the total weight of the collector used is the same for each experiment.

During the froth flotation process of this • invention, the use of frothers is preferred. Frothers are well-known in the art and reference is made thereto for the purposes of this invention. Any frother which results in the recovery of the desired metal-containing mineral is suitable. Frothers useful in this invention include any frothers known in the art which give the recovery of the desired mineral. Examples of such frothers include C ₅ _ _g alcohols, pine oils, cresols, C,_ ₄ alkyl ethers of polypropylene glycols, dihydroxyl- ates of polypropylene glycols, glycols, fatty acids, soaps, alkylaryl sulfonates, and the like. Furthermore, blends of such frothers may also be used. All frothers

which are suitable for beneficiation of ores by froth flotation can be used in this invention.

In addition, in the process of this invention it is contemplated that the collector combination which makes up the composition of this invention can be used in mixtures with other collectors well-known in the art.

The collector composition of this invention may also be used with an amount of other collectors known in the art which give the desired recovery of desired minerals. Examples of such other collectors useful in this invention include dialkyl and diaryl thiophosphonyl chlorides, mercapto benzothiazoles, fatty acids and salts of fatty acids, alkyl sulfuric acids and salts thereof, alkyl and alkaryl sulfonic acids and salts thereof, alkyl phosphoric acids and salts thereof, alkyl and aryl phosphoric acids and salts thereof, sulfosuccinates, sulfosuccinamates, primary amines, secondary amines, tertiary amines, quaternary ammonium salts, alkyl pyridinium salts, guanidine, and alkyl propylene diamines.

Specific Embodiments

The following examples are included for the purposes of illustration only and are not to be con- strued to limit the scope of the invention. Unless otherwise indicated, all parts and fractions are by weight.

In the examples, the performance of the frothing processes described is shown by giving the fractional amount of recovery at a specified time.

Example 1 - Froth Flotation of a Cu/Ni Ore

A series of samples of copper/nickel ore, containing chalcopyrite and pentlandite minerals, from

Eastern Canada having a high amount of iron sulfide in the form of pyrrhotite were drawn from feeders to plant rougher bank and placed in buckets. Each bucket held approximately 1200 g of solid. The contents of each bucket which had a pH of about 9 were used to generate a series of time-recovery profiles using the various collectors set forth in Table I. The profiles were made using a Denver cell equipped with an automated paddle and constant pulp level device. A frother and collector were added once with a condition time of one minute before froth removal was started. The dosage of the collectors was 0.028 kg/metric ton of flotation feed. A Dowfroth ® 1263 frother was also employed at a concentration of 0.0028 kg/metric ton. During the testing, individual concentrates were selected at 1, 3,

6 and 12 minutes for subsequent evaluation. The col- lected concentrates were dried, weighed, ground and statistically representative samples prepared for assay. Time-related recoveries and overall head grades were calculated using standard calculation procedures.

Results are presented in Table I.

TABLE I

Pyrrho- Cu Ni Gangue tite

Collector R-12 ² R-12 ² R-12 ² R-12 ² sodium amyl xanthate ¹ 0.939 0.842 0.039 0.333 ethyl 2-(hexylthio)- ethy1amide ¹ 0.936 0.830 0.048 0.477

ethyl 2-(hexylthio)- ethyl amide (75 weight percent) and sodium amyl 0.942 0.880 0.068 0.391 xanthate (25 weight percent)

N,N-dibutyl-l,2- ethane diamine ¹ 0.926 0.849 0.042 0.473

N,N-dibutyl-1,2-ethane diamine (75 weight percent) and sodium 0.957 0.883 0.062 0.466 amyl xanthate (25 weight percent) nonyl N-(2-amino- ethyl)amide ¹ 0.900 0.814 0.034 0.400

nonyl N-(2-aminoethyl)- amide (75 weight per- cent) and sodium 0.937 0.872 0.037 0.369 amyl xanthate (25 weight percent)

¹ l ^~ ot an example of the invention.

² R-12 is the fractional recovery after 12 minutes.

The 95 percent confidence levels of statistical error associated with Cu R-12 and Ni R-12 experimental values in Table I are ± 0.008 and ± 0.013, respectively. Thus the statistical range of R-12 values for Ni in Table I is 0.842 ± 0.013 Or 0.829 to 0.855. Applying

these limits clearly indicates that the recoveries of Cu and Ni with the collector blends of this invention exceed the 12 minute recoveries that would be expected from a weighted average effect of the individual co - ponents used alone. Synergism has occurred in the metal recovery with the additional benefit of getting lower undesired pyrrhotite recovery.

Example 2 - Froth Flotation of a Complex Pb/Zn/Cu/Ag Ore A series of uniform 1000 g samples of a complex Pb/Zn/Cu/Ag ore from Central Canada were pre¬ pared. The ore contained galena, sphalerite, chalco- pyrite and argentite. For each flotation run, a sample was added to a rod mill along with 500 ml of tap water and 7.5 ml of S0 ₂ solution. Six and one-half minutes of mill time were used to prepare the feed such that 90 percent of the ore had a particle size of less than 200 mesh (75 microns). After grinding, the contents were transferred to a cell fitted with an automated paddle for froth removal, and the cell was attached to a standard Denver ® flotation mechanism.

A two-stage flotation was then performed - Stage I being a copper/lead/silver rougher float and Stage II being a zinc rougher float. To start the Stage I flotation, 1.5 g/kg of Na ₂ C0 ₃ was added (pH of 9 to 9.5), followed by the addition of the collector(s). The pulp was then conditioned for 5 minutes with air and agitation. This was followed by a 2-minute condi¬ tion period with agitation only. A methyl isobutyl carbinol (MIBC) frother was then added (standard dose of 0.015 ml/kg). The concentrate was collected for 8 minutes of flotation and labeled as copper/lead rougher concentrate.

The Stage II flotation consisted of adding 0.5 kg/metric ton of CuS0 ₄ to the cell remains of Stage I. The pH was then adjusted to 10.5 with lime addition. This was followed by a condition period of 5 minutes with agitation only. The pH was then rechecked and adjusted back to 10.5 with lime. At this point, the collector(s) were added, followed by a five-minute condition period with agitation only. A methyl iso¬ butyl carbinol frother was then added (standard dose of 0.020 ml/kg). Concentrate was collected for 8 minutes and labeled as zinc rougher concentrate.

The concentrate samples were dried, weighed, and appropriate samples prepared for assay using X-ray techniques. Using the assay data, fractional recoveries and grades were calculated using standard mass balance formulae. The results are compiled in Table II.

TABLE II

Dosage

Run Stage Col¬ (kg/metric Ag Cu Pb Zn No. [Rougher) lector ton) pH R-8 R-8 R-8 R-8

9.5 0.463 0.332 0.264 0.026

10.5 0.313 0.405 0.437 0.672

D 0.016 9.5 0.188 0.150 0.027 0.011 D 0.023 10.5 0.615 0.457 0.806 0.866

D 0.007

Cu/Pb 9.5 0.549 0.444 0.288 0.035 B 0.009 D 0.008

Zn 10.5 0.297 0.373 0.531 0.899 0.015

*Not an example of the present invention

Collector A - sodium ethyl xanthate

Collector B - dithiophosphate

Collector C - thionocarbamate

Collector D - C ₆ H ₁₃ S(CH ₂ ) ₂ NH ₂

R-8 is the actual fractional recovery after 8 minutes

The 95 percent confidence levels of statis¬ tical error in the 8 minute recovery data of the Cu/Pb flotation (Stage I) are for Ag, ± 0.01; Cu, ± 0.01; and Pb, ± 0.02. Run 2 represents the test where single components were used in each stage.

In Stage I of Run 3, the addition of the two component blend of this invention as compared to the single component collector of Stage I of Run 2 gave significantly more Ag, Cu and Pb recovery. Ag, Cu and Pb values not recovered in Stage I were lost to this process and discarded.

The confidence region for Zn recovery in Stage II is ± 0.01. It is clear from the data of Run 3, Stage II, that the blend of this invention gave much higher Zn recovery than the individual component collectors.

Thus, significant recovery of all four metal-containing minerals has occurred.

Example 3 - Froth Flotation of CuO Ore Uniform 500 g samples of copper oxide ore, containing malachite mineral, from Western Australia were prepared as a slurry, previously adjusted to a pH of 10.4 by lime, using an Agitar 1500 ml cell. A series of initial floats (denoted as a sulfide float) were performed on these samples using the various col¬ lectors set forth in Table II at a dosage of 350 g/metric ton of ore. One minute of conditioning time was employed. The concentrate was removed for 3 minutes using a triethoxy butane frother as required. The recovered concentrate was then analyzed.

Oxide floats were then conducted on the samples by first adding 500 g/metric ton of sodium hydrosulfide to the cell residue. Following this addition, there was a two-minute condition period. A one-minute concentrate and a two- to five-minute concentrate were collected using a triethoxy butane frother as required. Twenty grams of potassium amyl xanthate and 35 grams of sodium hydrosulfide were added per ton of ore to the cell residue and conditioned for one minute. A five-minute concen¬ trate was then collected. An additional 20 grams of potassium amyl xanthate and 35 grams of sodium hydrosulfide per ton of ore were added to the cell residue and conditioned for one minute. A five- -minute concentrate was then collected. The col¬ lected concentrates and tails were dried, weighed and analyzed for total copper content using stand¬ ard analytical techniques. The results are pre¬ sented in Table III.

TABLE III

Sulfide Float Oxide Float 3 minutes 15 minutes Total Float 18 minutes

Collector Cu Recovery ³ Cu Recovery ³ Cu Grade ² Cu Recovery ³ potassium amyl xanthate ¹ 0.178 0.670 0.227 0.484

2-(hexylthio)ethyl amine ¹ 0.155 0.681 0.146 0.836

2-(hexylthioethyl)amine and potassium amyl xan¬ thate (both 50 weight 0.130 0.739 0.260 0.869 percent) ethyl 2-(hexy1thio)ethyl amide ¹ 0.111 0.618 0.179 0.729

ethyl 2-(hexylthio)ethyl amide and potassium amyl xanthate (both 50 weight 0.167 0.687 0.183 0.854 percent)

^x Not an example of the invention

² Grade is the fractional content of the specified metal in total weight collected in the froth fractional recoveries of metal-containing minerals

The statistical confidence levels of the experimental Cu recovery values in the 15 minute oxide float is ± 0.018. It is clear that the collector blends of this invention gave copper recoveries in the oxide float that significantly exceed those recoveries that would be expected from a weighted average effect of each component used alone. In addition, there are desirable benefits in improving the grade of the copper mineral floated with the blends of this invention.

Example 4 - Froth Flotation of a Ni/Co Ore

A large dry feed sample of nickel/cobalt ore, containing pentlandite and cobalt-containing mineral, from Western Australia was collected from which a series of test samples (750 grams) were pre- pared in slurry form. For the testing, an Agitar 1500 ml cell outfitted with a froth removal paddle was employed except for the final cleaner float which was done with a smaller cell and froth removed by hand. . The flotation procedure employed consisted of first adding 0.2 kg of CuS0 ₄ per metric ton of ore, conditioning the resulting mixture for 7 min¬ utes, adding 0.1 kg/ton collector and conditioning for 3 minutes. The mixture was then transferred from the conditioning vessel to the cell. Subse- quently, 0.14 kg of guar depressant (for talc) and 0.16 kg of collector per ton of ore and triethoxy butane frother as required to form a reasonable froth bed were added. The concentrate was collected for 5 minutes. The rougher concentrate was then transferred to a smaller cell and 0.08 kg of col¬ lector and 0.14 kg of guar per ton of ore was added to the cell. The concentrate was collected for 3 minutes. The collector content was denoted as

Cleaner Concentrate. The cell content was denoted as tails. Samples were filtered, dried, and pre¬ pared for assays. Recoveries were calculated using standard metallurgical procedures. The results are compiled in Table IV.

TABLE IV

Ni Rec ² Co Rec2

Cleaner Cleaner

Concen- Concen¬ Ni Co Collector trate trate Tails ³ Tails ³

¹ sodium ethyl 0.642 0. 687 0 .071 0 . 099 xanthate ¹

^s ai4)4&?fsaa€ 0.738 0.698 0.080 0.110

ethyl (2-hexyl- thio)ethylamide and sodium ethyl 0.801 0.768 0.065 0.099 xanthate (50 weight percent of each)

¹ Not an embodiment of this invention, fractional recovery of metal at end of flotation. ³ Tails are fraction of metal content remaining in cell after flotation.

The statistical confidence levels of the Ni and Co experimental recovery data were ± 0.013 and ± 0.019, respectively. Clearly, the Ni and Co recoveries associated with the blends of this invention significantly exceed those recoveries associated with the individual recoveries alone. Synergism has occurred.