WO1987003221A1

WO1987003221A1 - Novel collectors for froth flotation of minerals

Info

Publication number: WO1987003221A1
Application number: PCT/US1986/000341
Authority: WO
Inventors: Richard R. Klimpel; Robert D. Hansen
Original assignee: The Dow Chemical Company
Priority date: 1985-11-29
Filing date: 1986-02-18
Publication date: 1987-06-04
Also published as: ES552034A0; AU586471B2; PL147930B1; PL257990A1; SE8702988L; BR8607003A; SE8702988D0; RU1837985C; CN86101573A; FI873287A; ZM1486A1; AU5459886A; YU22986A; ZW4286A1; FI873287A0; PH24537A; JPS62129161A; YU45765B; ZA861171B; ES8706047A1

Abstract

A collector composition for use in froth flotation processes comprises two collectors. One of the collectors is preferably an omega-(hydrocarbylthio)-alkylamine, S-(omega-aminoalkyl) hydrocarbyl thioate, N-(hydrocarbyl)-alpha, omega-alkanediamine, (omega-aminoalkyl) hydrocarbon amide, omega-(hydrocarbyloxy)-alkylamine, omega-aminoalkyl hydrocarbonate, omega-(hydrocarbylthio)alkylamide or mixture thereof. The second collector is a thiocarbonate, a thionocarbamate, a thiophosphate, thiocarbinilide, thiophosphinate, mercaptan, xanthogen formate, xanthic ester or mixture thereof. The collector composition floats a broad range of metal-containing minerals.

Description

NOVEL COLLECTORS FOR FROTH FLOTATION OF MINERALS

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 materials suspended therein causes adherence of some gas to certain suspended solids and not to others and makes the particles having the gas thus adhered thereto lighter than the liquid. Accordingly, 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, thionocarbamates 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 functioning as such on a mineral which it is desired to retain in the liquid, and thereby discourage a substance from being carried up and 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 additives 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 sulfidized 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-containing oxide minerals without recovering the iron-containing sulfide minerals such as pyrite and pyrrhotite. Of the commercial collectors, the xanthates, thionocarbamates, and dithiophosphates do not selectively 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 polysulfides are not generally used commercially. Furthermore, the mercaptans, disulfides and polysulfides 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:

R¹-x-(R)_n-Q wherein Q is

-N(R²)_a(H)_b where a + b equals 2,

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

≡N, or

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_1-22 hydrocarbyl radical, a C_1-22 substituted hydrocarbyl radical, or a saturated or unsaturated heterocyclic ring;

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;

3 where R is hydrogen, a C_1-22 hydrocarbyl radical or a substituted C_1-22 hydrocarbyl radical; and (b) an alkyl thiocarbonate, a thionocarbamate, a thiophosphate, a thiocarbanilide, a thiophosphinate, a mercaptan, a xanthogen formate, a xanthic ester or mixture thereof.

In another aspect, the invention also concerns 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 flotation 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-containing 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 recoveries, often with better grade, than can be achieved with the use of either collector component alone.

In a preferred process of the present invention, 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 metalcontaining 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 (-CH₂-)_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 C_1-22 hydrocarbyl radical or a C_1-22 hydrocarbyl 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, R¹ or R² is advantageously substitued with one or more hydroxy, halo, amino, phosphonyl or alkoxy moiety. Q is preferably -N(R²)_a(H)_b where a + b equals 2. More advantageously, the carbon atoms in R¹ and R² total 6 or more with R¹ preferably being a C_2-14 hydrocarbyl, or a C_2-14 hydrocarbyl substituted with one or more hydroxy, amino, phosphonyl, or alkoxy groups, more preferably a C_4-11 hydrocarbyl; and R² preferably being a C_1-6 alkyl, C_1-6 alkylcarbonyl or C_1-6-substituted alkyl or alkylcarbonyl, more preferably a C_1-4 alkyl or C_1-4 alkylcarbonyl or a C_1-6 alkyl or C_1-6 alkylcarbonyl substituted with an amino, hydroxy or phosphonyl group, and most preferably a C_1-2 alkyl or C_1-2 alkylcarbonyl. In addition, R is preferably

(-CH₂-)_p or

more preferably (-CH₂-)_p; n is preferably an integer from 1 to 4, most preferably 2 or 3; X is preferably -S-, -N '-R³, or -O-, more preferably -S- or -N'-R³, most preferably -S-; and R ³ is preferably hydrogen or C_1-14 hydrocarbyl, more preferably hydrogen or C_1-11 hydrocarbyl, most preferably hydrogen.

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

the S-(omega-aminoalkyl) hydrocarbonthioates:

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

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

the N-(omega-aminoalkyl) hydrocarbon amides:

the omega-(hydrocarbyloxy-)alkylamines: f > f

and the omega-aminoalkyl hydrocarbonoates: f f

wherein R¹, R², R³, a, b and n are as hereinbefore defined. In formulas II-VII, when X is -S- or

R¹ is preferably a C_4-10 hydrocarbyl; when X is

the total carbon content of the groups R¹ and R³ is preferably between 1 and 23, more preferably 2 and 16, and most preferably 4 and 15; and when X is

R¹ is most preferably C_6-11 hydrocarbyl.

Of the foregoing, the preferred component

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

omega-(hydrocarbyloxy-)alkylamines, N-(omega-aminoalkyl)hydrocarbon amide, omega-(hydrocarbylthio)- alkylamide or mixtures thereof. More preferred component (a) compounds include omega-(hydrocarbylthio)- alkylamines, N-(hydrocarbyl)-alpha,omega-alkanediamines, N-(omega-aminoalkyl)hydrocarbon amides, omega-(hydrocarbylthio)alkylamide or mixtures thereof. The most preferred class of component (a) compounds are the omega-(hydrocarbylthio)alkylamines and omega-(hydrocarbylthio)alkylamide. Especially preferred compounds are 2-(hexylthio)ethylamine and ethyl 2-(hexylthio)ethylamide.

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-alkanediamines 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 thionocarbamate, 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: (VII

wherein

R⁴ is a C_1-20, preferably C_2-16, more preferably C_3-12 alkyl group; Z¹ 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 Z¹ and Z² are oxygen), alkyl dithiocarbonates (Z¹=0, Z²=S) and the alkyl trithiocarbonates (both Z¹ and Z² are sulfur)

Examples of preferred alkyl monothiocarbonates include sodium ethyl monothiocarbonate, sodium isopropyl monothiocarbonate, sodium isobutyl monothiocarbonate, sodium amyl monothiocarbonate, potassium ethyl monothiocarbonate, potassium isopropyl monothiocarbonate, potassium isobutyl monothiocarbonate, and potassium amyl monothiocarbonate. Preferred alkyl dithiocarbonates include potassium ethyl dithiocarbonate, sodium ethyl dithiocarbonate, potassium amyl dithiocarbonate, sodium amyl dithiocarbonate, potassium isopropyl dithiocarbonate, sodium isopropyl dithiocarbonate, sodium sec-butyl dithiocarbonate, potassium sec-butyl dithiocarbonate, sodium isobutyl dithiocarbonate, potassium isobutyl dithiocarbonate, and the like. Examples of alkyl trithiocarbonates 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

wherein

R⁵ is independantly a C_1-10, preferably a C_1-4, more preferably a C_1-3, alkyl group;

Y is -S -M⁺ or -OR⁶, wherein R⁶ is a C_2-10, Preferably 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⁺) and alkyl thionocarbamates (c=1, d=1 and Y is -OR⁶)

Examples of preferred dialkyl dithiocarbamates include methyl butyl dithiocarbamate, methyl isobutyl dithiocarbamate, methyl sec-butyl dithiocarbamate, methyl propyl dithiocarbamate, methyl iso propyl dithiocarbamate, ethyl butyl dithiocarbamate, ethyl isobutyl dithiocarbamate, ethyl sec- -butyl dithiocarbamate, ethyl propyl dithiocarbamate, and ethyl isopropyl dithiocarbamate. Exampies 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 thionocarbamate, N-ethyl propyl thionocarbamate, and N-ethyl isopropyl thionocarbamate. Of the foregoing, N-ethyl isopropyl thionocarbamate and N-ethyl isobutyl thionocarbamate are most preferred.

Thiophosphates useful herein generally correspond to the formula

wherein R⁷ is independently hydrogen or a C_1-10, preferably C_2-8, alkyl group or an aryl, preferably an aryl group having from 6-10 carbon atoms, most preferably 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 dithiophosphates (one R⁷ is hydrogen and the other R⁷ is a C_1-10 alkyl and Z is S-), dialkyl dithiophosphates (both R⁷ are C_1-10 alkyl and Z is S-), dialkyl monothiophosphate (both R⁷ are a C_1-10 alkyl and Z is O-), and diaryl dithiophosphate (both R⁷ are aryl and Z is S-)

Examples of preferred monoalkyl dithiophosphates include ethyl dithiophosphate, propyl dithiophosphate, isopropyl dithiophosphate, butyl dithiophosphate, sec-butyl dithiophosphate, and isobutyl dithiophosphate. Examples of dialkyl or diaryl dithiophosphates include sodium diethyl dithiophosphate, sodium di-sec-butyl dithiophosphate, sodium diisobutyl dithiophosphate, sodium diisoamyl dithiophosphate and sodium dicresyl dithiophosphate. Preferred monothiophosphates include sodium diethyl monothiophosphate, sodium di-sec-butyl monothiophosphate, sodium diisobutyl monothiophosphate, and sodium diisoamyl monothiophosphate.

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

wherein R₁₁ is individually H or a C_1-6, preferably a C_1-3, hydrocarbyl.

Thiophosphinates are represented by the general structural formula:

wherein M⁺ is as hereinbefore described and R₁₂ 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 R₁₂ is isobutyl.

Mercaptan collectors are preferably alkyl mercaptans represented by the general structural formula:

wherein R₁₃ 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:

wherein R₁₄ is an alkyl group having from 1 to 7, preferably from 2 to 6 carbon atoms and R₁₅ 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 R₁₆ is an allyl group having from 2 to 7 carbon atoms, and R₁₇ is an alkyl group having from 1 to 7 carbon atoms

Preferred compounds for use as component (b) herein are the thiocarbonates, thionocar- bamates and the thiophosphates due to the surprisingly 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 compounds: alkanes, alkenes, alkynes, cycloalkanes, cycloalkenes, cycloalkynes, aromatics, aliphatic and cycloaliphatic 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 saturated 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, cycloalkenyl, aryl, aliphatic and cycloaliphatic aralkyl and alkaryl. The term aryl refers herein to biaryl, biphenylyl, phenyl, naphthyl, phenanthrenyl, anthracenyl 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_1-20 alkyl includes straight and branchedchain 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 saturated and unsaturated heterocyclic rings, including an -N-cyclic ring. The heterocyclic ring may include one or more N, O or S atoms. Examples of suitable heterocyclic rings are pyridine, pyrazole, furan, thiophene, indole, benzofuran, benzothiophene, quinoline, isoquinoline, 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 flotation 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 composition 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 component (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-(hydrocarbylthio)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 dithiocarbonate or alkyl trithiocarbonate.

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 (Cu₂S), chalco- pyrite (CuFeS₂), valleriite (Cu₂Fe₄S₇ or Cu₃Fe₄S₇), bornite (Cu₅FeS₄), cubanite (Cu₂SFe₄S₅), enargite [Cu₃(As₁Sb)S₄], tetrahedrite (Cu₃SbS₂), tennantite (Cu₁₂As₄S₁₃), brochantite [Cu₄(OH)gSO₄], antlerite

[Cu₃SO₄(OH)₄], famatinite (Cu₃(SbAs)S₄), and bournonite (PbCuSbS₃); lead-bearing minerals such as, for example, galena (PbS); antimony-bearing minerals such as, for example, stibnite (Sb₂S₃); zinc-bearing minerals such as, for example, sphalerite (ZnS); silver-bearing minerals such as, for example, stephanite (Ag₅SbS₄) and argentite (Ag₂S); chromium-bearing minerals such as, for example, daubreelite (FeSCrS₃); nickel-bearing minerals such as, for example, pentlandite [(FeNi)S₈]; molybdenum-bearing minerals such as, for example, molybdenite (MoS₂); and platinum- and palladium-bearing minerals such as, for example, cooperite [Pt(AsS)₂]. Preferred metal-containing sulfide minerals include molybdenite (MoS₂), chalcopyrite (CuFeS₂), galena (PBS), sphalerite (ZnS), bornite (Cu₅FeS₄), and pent- landite [(FeNi)₉S₈].

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, molybdenum, 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 (Cu₂O), tenorite (CuO), malachite [Cu₂(OH)₂CO₃], azurite [Cu₃(OH)₂(CO₃)₂], atacamite [Cu₂Cl(OH)₃], chrysocolla (CuSiO₃); aluminum-bearing minerals, such as corundum; zinc-containing minerals, such as zincite (ZnO) and smithsonite (ZnCO₃); tungsten-bearing minerals such as wolframite [(Fe,Mn)WO₄]; nickel-bearing minerals such as bunsenite (NiO); molybdenum-bearing minerals such as wulfenite (PbMoO₄) and powellite (CaMoO₄); iron-containing minerals, such as hematite and magnetite; chromium-containing minerals, such as chromite (FeOCr₂O₃), 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; tincontaining minerals, such as cassiterite; and uraniumcontaining minerals, such as uraninite; and uraniumbearing minerals, such as, for example, pitchblende [U₂O₅(U₃O₈)] and gummite (UO₃nH₂O).

Other metal-containing minerals for which this process is useful include gold-bearing minerals, such as sylvanite (AuAgTe₂) and calaverite (AuTe); platinum- and palladium-bearing minerals, such as sperrylite (PtAs₂); and silver-bearing minerals, such as hessite (AgTe₂). 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 particular 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 synergistic 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_5-8 alcohols, pine oils, cresols, C_1-4 alkyl ethers of polypropylene glycols, dihydroxylates 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 construed 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 collected 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.

¹ Not an example of the invention.

²R-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 components 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 prepared. The ore contained galena, sphalerite, chalcopyrite 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 SO₂ 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 Na₂CO₃ 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 condition 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 CuSO₄ 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 isobutyl 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.

The 95 percent confidence levels of statistical 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 collectors 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 concentrate 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 collected concentrates and tails were dried, weighed and analyzed for total copper content using standard analytical techniques. The results are presented in Table III.

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 prepared 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 CuSO₄ per metric ton of ore, conditioning the resulting mixture for 7 minutes, adding 0.1 kg/ton collector and conditioning for 3 minutes. The mixture was then transferred from the conditioning vessel to the cell. Subsequently, 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 collector 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 prepared for assays. Recoveries were calculated using standard metallurgical procedures. The results are compiled in Table IV.

¹Not an embodiment of this invention, 2Fractional recovery of metal at end of flotation. 3Tails 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.

Claims

1. A composition for the flotation of metal-containing minerals which comprises: (a) a compound of the formula:

R¹-X-(R)_n-Q

I wherein Q is

-N(R²)_a(H)_b where a + b equals 2,

≡N, or

R¹ and R² are independently a C_1-22 hydrocarbyl radical, a C_1-22 substituted hydrocarbyl radical, or a saturated or unsaturated heterocyclic ring;

where R³ is hydrogen, a C_1-22 hydrocarbyl radical or a substituted C_1-22 hydrocarbyl radical; and

(b) an alkyl thiocarbonate, a thionocarbamate, a thiophosphate, a thiocarbanilide, thiophosphinate, mercaptan, xanthogen formate, xanthic ester or mixtures thereof.

2. The collector composition of Claim 1 wherein component (a) and component (b) are employed in amounts such that the composition is an effective collector for minerals in a froth flotation process.

3. The composition of Claim 2 wherein the component (a) is a compound of the structural formula:

la wherein R¹ is a C_2-14 hydrocarbyl radical or a C_2-14 hydrocarbyl substituted with one or more hydroxy, amino, phosphonyl, or alkoxy moieties and R² is a C_1-6 alkyl, C_1-6 alkylcarbonyl, or a C_1-6 alkyl or a C_1-6 alkylcarbonyl group substituted with an amino, hydroxy or phosphonyl moiety, a is 0 or 1 and b is 1 or 2 and a + b = 2.

4. The composition of Claim 3 wherein component (b) is an alkyl thiocarbonate of the structural formula:

IX a thionocarbamate of the structural formula:

X a thiophosphate of the structural formula:

XI or mixtures thereof, where R⁴ is a C_1-20 alkyl group; R⁵ is independently a C_1-10 alkyl group; Y is -S-M⁺ or

-OR⁶; R⁶ is a C_2-10 alkyl group; R⁷ is independently hydrogen, a C_1-10 alkyl group or an aryl group; M is an alkali metal cation; Z, Z¹ and Z² are independently

S or O; c is the integer 1 or 2; and d is the integer 0 or 1, with the proviso that the sum of c plus d equal

2.

5. The composition of Claim 4 wherein component (a) is an omega-(hydrocarbylthio)alkyl- amine; S-(omega-aminoalkyl) hydrocarbon thioate; N- -(hydrocarbyl)-alpha, omega-alkanediamine; (omega- -aminoalkyl) hydrocarbon amide; omega- (hydrocarbyl- oxy)alkylamine; omega-aminoalkyl hydrocarbonoate; omega-(hydrocarbylthio)alkylamide or mixture thereof.

6. The composition of Claim 5 which comprises:

(a) from about 10 to about 90 percent by weight of omega-(hydrocarbylthio)alkyl- amine, S-(omega-aminoalkyl) hydrocarbon thioate, N- (hydrocarbyl)-alpha,omega-alkanediamine, (omega-aminoalkyl) hydrocarbon amide, omega-(hydrocarbyloxy)alkylamine, omega-

-aminoalkyl hydrocarbonoate, omega- (hydrocarbylthio)alkylamide or mixture thereof; and

(b) from about 10 to about 90 percent by weight of an alkyl thiocarbonate, thionocarbamate, thiophosphate or mixture thereof.

7. The composition of Claim 6 which comprises:

(a) from about 20 to about 80 percent by weight of omega-(hydrocarbylthio)alkyl- amine, S-(omega-aminoalkyl) hydrocarbon thioate, N-(hydrocarbyl)-alpha, omega-alkanediamine, (omega-aminoalkyl) hydrocarbon amide, omega-(hydrocarbyloxy)alkylamine, omega- -aminoalkyl hydrocarbonoate, omega-(hydrocarbylthio)alkylamide or mixture thereof; and (b) from about 20 to about 80 percent by weight of an alkyl thiocarbonate, thionocarbamate, thiophosphate or mixture thereof.

8. The composition of Claim 7 wherein

R is -CH₂- or

R¹ is C_1-14 hydrocarbyl; R² is C_1-6 alkyl or C_1-6 alkylcarbonyl; R³ is hydrogen or C_1-14 hydrocarbyl; R⁴ is C_1-16 alkyl; R⁵ is C_1-4 alkyl; R⁶ is C_2-6 alkyl; R⁷ is cresyl or C_2-6 alkyl; M is sodium or potassium; a is the integer 0 or 1; b is the integer 1 or 2; and n is an integer of from 1 to

4.

9. The composition of Claim 8 wherein

R¹ is C_4-11 hydrocarbyl; R² is C_1-4 alkyl or C_1-4 alkylcarbonyl; R³ is hydrogen or C_1-11 hydrocarbyl; n is the integer 2 or 3; X is -S-, -N-R³ or -0-;

R⁴ is C_3-12 alkyl; R⁵ is C_1-3 alkyl; and R⁶ is C_3-4 alkyl.

10. The composition of Claim 9 which comprises:

(a) an omega-(hydrocarbylthio)alkyl- amine, an N-(hydrocarbyl)-alpha, omega-alkane- diamine, an N-(omega-aminoalkyl)hydrocarbon amide, omega-(hydrocarbyloxy)alkylamine omega- -(hydrocarbylthio)alkylamide or mixture thereof; and (b) comprises a mixture of an alkyl monothiocarbonate, alkyl dithiocarbonate or alkyl trithiocarbonate.

11. The composition of Claim 10 which comprises:

(a) an omega-(hydrocarbylthio)alkylamine, or omega-(hydrocarbylthio)alkylamide; and

(b) a mixture of an alkyl monothiocarbonate, alkyl dithiocarbonate or alkyl trithiocarbonate.

12. The composition of Claim 9 wherein X is

13. The composition of Claim 12 wherein X is -S-.

14. The composition of Claim 1 wherein component (a) is omega-(hydrocarbylthio)alkylamide or omega-(hydrocarbylthio)alkylamine.

15. The composition of Claim 14 wherein component (a) is 2-(hexylthio)ethylamine or ethyl 2-(hexylthio)ethylamide.

16. A process for recovering metal-containing 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 flotation collector composition of any one of Claims 1 to 15.

17. The process of Claim 16 wherein a metal-containing sulfide mineral is recovered in the froth.

18. The process of Claim 16 wherein the metal-containing mineral recovered in the froth contains copper, zinc, molybdenum, cobalt, nickel, lead, arsenic, silver, chromium, gold, platinum, uranium, or mixture thereof.

19. The process of Claim 17 wherein the metal-containing sulfide mineral recovered in the froth is molybdenite, chalcopyrite, galena, sphalerite, bornite, or pentlandite.

20. The process of Claim 16 wherein the collector composition is present in a concentration of from 0.001 to 1.0 kg of collector/metric ton of ore to be subjected to froth flotation.