Polysulfide compositions and methods for separation of ores

Abstract

A froth flotation composition for the separation of certain minerals in an ore is provided. The composition can comprise an aqueous medium, a frother, a collector formulation, and optionally a pH modifier, with the collector formulation specifically including at least a polysulfide collector having one or more -Sn- moieties in which n is at least 3 and comprising from 9 wt% to 45 wt% sulfur content, based on a total weight of the poly sulfide. A method for separation of minerals in an ore is also provided. The method can include introducing into a separation apparatus the components of the froth flotation composition and separating some or all of the ore into a plurality of minerals, such as to form a mineral concentrate.

Description

[0001] POLYSULFIDE COMPOSITIONS AND METHODS FOR SEPARATION OF ORES

[0002] FIELD OF THE INVENTION

[0003] This disclosure relates to compositions and methods useful for the froth flotation separation of minerals in ores.

[0004] BACKGROUND

[0005] Froth flotation, or flotation, is a process of extracting a metal from low-content ores by a stage of concentration. This stage comes before a subsequent treatment comprising the heat treatment (also known as smelting) or the leaching and the refining. This is in particular the case with ores of oxides and / or sulfides of lead, zinc, copper, silver, gold, molybdenum, nickel, cobalt, iron, arsenic, magnesium, cadmium, tellurium, and / or metals belonging to the platinum group: platinum, palladium, rhodium, ruthenium, iridium and osmium.

[0006] Flotation is a method that concentrates and separates the valuable components of an ore from the undesirable components, “gangue,” to produce a mineral concentrate that is fed to pyrometallurgical or hydro-metallurgical operations. The process of froth flotation starts by crushing ore into fine particles to provide separate particles of desirable minerals and the undesirable gangue components, and then frothing or “pulping” the ore particles with water. Before the frothing process, the aqueous ore particles are combined with a flotation composition, also referred to as a flotation agent or as a collector or collector agent, which comprises appropriate additives. These flotation agents selectively render the surfaces of the different types of particles hydrophobic and / or hydrophilic, based on their individual compositions. The frothing is done by passing stream of air or inert gas bubbles through the aqueous composition of ore and flotation agent, sometimes called “pulp,” in a flotation cell, such that the gas bubbles attach to and levitate the now-hydrophobic particles. These levitated particles, attached to the air bubbles, then collect in a froth layer which flows over the weir of the flotation cell. The undesirable gangue may be either unaffected by the flotation agent, or rendered hydrophilic and thus settles to the bottom of the flotation cell.

[0007] As discussed above, froth flotation works by separating minerals from gangue by exploiting differences in their hydrophobicity. Hydrophobicity differences between valuable minerals and waste gangue are increased through the use of surfactants and wetting agents which affect the various compounds in the crushed ore differently. The adhesion of the bubbles to the crystals is promoted by the action of the flotation agent or agents used. The crystals of the metal compounds then rise to the surface and are recovered in the form of a foam, also known as flotation concentrate. The gangue particles are recovered in the lower part of the flotation cell.

[0008] The flotation concentrate which flows over the weir at the top of the flotation cell has a content of desired metal which is therefore considerably higher than that in the starting ore. This content depends on the initial content in the ore and on the selectivity of the composition of the flotation agent.

[0009] After a stage of filtration and drying, the flotation concentrates are then introduced into the heat treatment (or smelting) stage. This stage is typically a furnace at temperatures which may exceed 1500° C. During this stage, the desired metal is separated in the molten state from the other substances, in particular from the impurities originating from the gangue of the ore, which have to be removed in the form of a slag.

[0010] U.S. Patent No. 2,012,446 discloses sulfurization of pine oil with elemental sulfur, but for addition to a lubricant so as to form a cutting oil.

[0011] U.S. Patent No. 2,111,882 discloses sulfurization of various organic compounds including pine oil and turpentine with elemental sulfur.

[0012] U.S. Patent No. 2,631,131 discloses sulfurization tall oil with elemental sulfur, but for addition to a mineral oil with the goal of making a cutting oil.

[0013] U.S. Patent No. 4,053,427 discloses sulfurization of mixtures of organic fatty acid esters and olefins, but specifically for use as an extreme pressure agent in lubricating oils.

[0014] U.S. Patent No. 4,211,644 discloses a collector composition for use in concentrating metallic mineral ores by froth flotation which comprises a mixture of a mercaptan and an emulsifying or wetting agent adapted to improve the dispersion of the mercaptan into the pulp, and a froth flotation method for concentrating metallic mineral ores wherein the above collector composition is employed as the collector. U.S. Patent No. 4,554,137 discloses a process of enrichment of minerals by flotation by use of a collector comprising a thio-compound, the thio compound being a straight or branched dialkyl or dialkenyl polysulphide.

[0015] U.S. Patent No. 4,556,500 discloses a composition and process for the recovery of the values of zinc, molybdenum, copper, lead, iron (pyrite), and iron-containing small amounts of gold or uranium, or both, from ores comprising these mineral sulfides. The aqueous composition is the impure form of an alkali metal alkyl trithiocarbonate compound. The process comprises employing the aqueous composition as a collection agent for the above minerals in an ore recovery process.

[0016] U.S. Patent No. 4,594,151 discloses a process of flotation of minerals, which consists of introducing the flotation collector into the mineral pulp to be treated in the form of a microemulsifiable composition. In general, the collector agents are organic compounds containing sulfur, particularly mercaptans, thioethers or polysulfides, which generally are very slightly soluble in water.

[0017] U.S. Patent No. 4,857,179 discloses a flotation agent made from sulfurizing dicyclopentadiene, but by reaction with hydrogen sulfide instead of elemental sulfur.

[0018] PCT Publication No. WO 90 / 004459 discloses collectors in the flotation of non-sulfidic ores obtained by reacting epoxidized fatty acid esters with sulfur trioxide instead of elemental sulfur.

[0019] U.S. Patent No. 7,014,048 discloses compositions intended for the flotation of ores, including a combination (A) of n-dodecyl mercaptan (or NDM) and of tert-dodecyl mercaptan (or TDM), the NDM / TDM ratio by weight of which is between 0.5 and 1.5, a product (B) composed of one or more aromatic or aliphatic compounds comprising from 4 to 100 carbon atoms, and having one or two -OH groups.

[0020] U.S. Patent No. 9,447,481 discloses mining collector compositions made from mercaptizing organic olefms including limonene.

[0021] U.S. Patent No. 9,522,975 discloses intermolecular (mono-)sulfides and thiols based on sulfurization of vinyl Norbomene. U.S. Patent No. 9,527,090 discloses a process for the recovery of a metal from an ore using a collector composition. The process includes contacting the ore with the collector composition. The collector composition includes specific sulfur-containing compounds.

[0022] U.S. Patent No. 9,597,693 discloses mercaptized and (mono-)sulfieded dicyclopentadiene compositions for use as mining chemical collectors.

[0023] U.S. Patent Application Publication No. 2018 / 0036742 discloses water-based mining collector compositions containing dodecylmethyl (mono-)sulfides.

[0024] Accordingly, it is important to use a flotation agent / collector that provides a flotation concentrate having a suitably high content of the desired metal, so as to facilitate the subsequent operations of treatment of the said concentrate and of final isolation of the metal.

[0025] SUMMARY

[0026] Provided herein are methods for separation of minerals in an ore, froth flotation separation compositions made therefor, as uses of such compositions specifically to undertake the methods.

[0027] A method for separation of minerals in an ore can comprise introducing into a separation apparatus a slurry comprising the ore to be separated and an aqueous medium comprising water, as well as an effective amount of a collector formulation comprising a polysulfide. The method can also comprise separating some or all of the ore into a plurality of minerals. The ore to be separated can comprise sulfide minerals and / or precious metals based on one or more of Cu, Mo, Pb, Zn, Ni, Co, Fe, As, Mg, Cd, Pd, Pt, Ru, Ir, Os, Te, Au, and Ag (in particular based on Cu, Mo, Fe, Au, Ag, or a combination thereof). The polysulfide can exhibit one or more -Sn- moieties in which n is at least 4 and can comprise from 9 wt% to 45 wt% sulfur content, in particular from 16 wt% to 40 wt%, based on a total weight of the poly sulfide. The collector formulation can optionally comprise an additional collector, a hydrocarbon diluent, a dispersant, or a combination thereof.

[0028] The separating step can comprise or be flotation separation. In many embodiments, the plurality of minerals from the separating step can comprise (directly or indirectly form) a mineral concentrate. The separating step can comprise sparging the slurry with a gas, optionally but preferably comprising nitrogen.

[0029] In some embodiments, the collector formulation can be added to the ore to be separated prior to formation of the slurry with the aqueous medium (termed “to the grind” herein).

[0030] In many embodiments, a frother can be introduced before or during the separating step, but typically separate from the collector formulation.

[0031] In some embodiments, the collector formulation can comprise a depressant, such as an Fe depressant, which can be added before, during or after the polysulfide collector.

[0032] In some embodiments, a pH of the slurry can be controlled, for example to be from 8 to 12, in particular from 9 to 11. The pH of the slurry can be controlled through addition of a basic compound, such as comprising a hydroxyl group and lithium, sodium, potassium, calcium, or a combination thereof.

[0033] In some embodiments, the polysulfide can be comprised of a sulfurized olefin, a sulfurized vegetable-based fatty acid, a sulfurized fatty acid C1-C4 alkyl ester, or a combination thereof.

[0034] In other embodiments, the polysulfide can be comprised from a reaction product of elemental sulfur and one or more unsaturated hydrocarbon and / or oxygen heteroatom-containing hydrocarbon compounds. In certain of these other embodiments, the reaction product can comprise substantially no residual mercaptan (e.g.. measurable by silver titration) and / or substantially no residual ethoxylate (e.g., as measurable by 'H NMR). In such embodiments, the one or more unsaturated hydrocarbon and / or oxygen heteroatom-containing hydrocarbon compounds comprises limonene, myrcene, ethylidene norbomene, vinyl norbomene, di cyclopentadiene, pine oil, tall oil, soybean oil, C10-C16 olefins, Cl 1 -Cl 8 unsaturated fatty acids and / or C1-C4 alkyl esters, or a combination thereof (in particular limonene, dicyclopentadiene, soybean oil, propylene tetramer, butylene trimer, Cl 1-C18 unsaturated fatty acids and / or C1-C4 alkyl esters, or a combination thereof). For such reaction products, the one or more unsaturated hydrocarbon and / or oxygen heteroatom-containing hydrocarbon compounds and the elemental sulfur can be reacted, in particular in the absence of a catalyst such as an amine catalyst, e.g., at a temperature ranging from about 130°C to about 200°C for a time period from about 5 minutes to about 1 day.

[0035] In some embodiments, the collector formulation can consist essentially of the poly sulfide collector, an additional collector, and a diluent. In other embodiments, the collector formulation can consist essentially of the polysulfide collector, one or more additional collectors, and optionally a dispersant.

[0036] A froth flotation separation composition can comprise an aqueous medium, a frother, a collector formulation, and optionally a pH modifier. In particular embodiments, the collector formulation can consist essentially of: a polysulfide collector disclosed herein; optionally an additional collector (e.g., comprising n-dodecyl mercaptan, tert-dodecyl mercaptan, isopropyl ethylthionocarbamate, potassium amyl xanthate, sodium dicresyl dithiophosphate, or a combination thereof); optionally a hydrocarbon diluent e.g., comprising kerosene); optionally a dispersant (e.g., comprising 2-ethylhexanol, a polypropylene glycol), or a combination thereof); and optionally a depressant (e.g., comprising dextrin). The optional pH modifier can comprise a hydroxyl group and lithium, sodium, potassium, calcium, or a combination thereof, but in some embodiments can comprise substantially no sodium cyanide nor potassium cyanide.

[0037] Such a froth flotation separation composition can be used in a froth flotation separation method (such as described herein) to separate minerals in an ore comprising sulfide minerals and / or precious metals (e.g., based on Cu, Mo, Fe, Au, Ag, or a combination thereof), such as to directly or indirectly form a mineral concentrate.

[0038] BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 shows a comparative ’H NMR analysis of limonene reactant and a sulfurized product of limonene and elemental sulfur (-35% sulfur) showing substantially complete reaction of limonene carbon-carbon double bonds.

[0040] Figure 2 shows comparative x-ray diffraction of sulfurized products using limonene reactant (bottom) and a limonene / dicyclopentadiene mixed reactant (top). The inset figure is the reference spectrum for elemental sulfur in the same wavespace, for comparison. Figure 3 shows a left-side Raman spectroscopy analysis of a sulfurized product of limonene with various peaks assigned to different sulfides / polysulfides, blown up on the rightside in the sulfide / polysulfide wavenumber region of interest to show peak deconvolution / baseline.

[0041] Figure 4 shows chalcopyrite recovery versus pH in Hallimond tube systems for polysulfide collector formulations based on sulfurized limonene (and comparative formulations containing no polysulfide).

[0042] Figure 5 shows chalcopyrite recovery versus pH in Hallimond tube systems for polysulfide collector formulations based on various sulfurized reactive compounds, as diluted in kerosene (and comparative formulations containing potassium amyl xanthate).

[0043] Figure 6 shows copper recovery versus copper grade for froth flotation separation involving polysulfide collector formulations based on sulfurized limonene (and comparative formulations containing no poly sulfide).

[0044] Figure 7 shows a graph of copper recovery versus copper grade for froth flotation separation involving various polysulfide collectors in a Cu- / Au- containing ore, as compared to a Standard.

[0045] Figure 8 shows a graph of cumulative copper recovery versus cumulative copper grade for froth flotation separation involving various polysulfide collectors in a Cu-containing ore, as compared to a Standard.

[0046] Figure 9 shows a graph of cumulative copper recovery versus cumulative copper grade for froth flotation separation involving various polysulfide collectors in a Cu- / Au- containing ore, as compared to a Standard.

[0047] Figure 10 shows a graph of copper recovery versus iron recovery for froth flotation separation involving various polysulfide collectors in a Cu- / Au- containing ore, as compared to a Standard.

[0048] Figure 11 shows a graph of copper recovery versus iron recovery for froth flotation separation involving various polysulfide collectors in a Cu-containing ore, as compared to a Standard. DETAILED DESCRIPTION

[0049] As used herein, typically with respect to one or more components having one or more enumerated functions, the phrase “effective amount” means an amount of a component that is effective to perform at least one of its stated functions as an improvement over performance in the absence of other components performing its function. For example, an “effective amount” of a collector (or of a collector formulation) can selectively increase froth flotation collection of an ore / mineral by at least 20%, in particular by at least 33% or at least 50%, as compared to no collector (or collector formulation) at all.

[0050] Collector formulations according to this disclosure may advantageously contain a polysulfide collector described below, as well as one or more other optional components, which can include but are not necessarily limited to an additional collector, a dispersant, a depressant, a diluent, a pH modifier, and a frother / surfactant (although this latter optional component may typically be added separately from the collector formulation - in many cases, whether added separately or together, the frother / surfactant may not always be strictly considered an element of the collector formulation). Various factors can be involved in whether to add any component other than a polysulfide collector described herein, which to add, and in what relative amounts. Such factors can typically include the type(s) of mineral(s) to be collected in the particular ore, but rarely is a single factor dispositive.

[0051] Polysulfide Collectors

[0052] As used herein, a “collector” is a compound that selectively reacts and / or complexes (physically and / or chemically associates) with certain minerals or ore components (usually particulate in a slurry medium), causing them to phase separate from other (usually particulate) minerals or ore components (e.g., to be more likely to be entrained on the surface of or within a gas bubble or other non-aqueous component in a froth flotation separation, such as within a flotation cell), usually by increasing the hydrophobicity of the certain minerals or ore components, relative to the other surrounding minerals or ore components.

[0053] Polysulfide collectors according to this disclosure can advantageously possess relatively long sulfur chains, e.g., having one or more -Sn- moieties in which n is at least 3, in particular at least 4. Additionally or alternatively, polysulfide collectors according to this disclosure can advantageously comprise an intermediate to high sulfur content (e.g., from ~9 wt% to ~45 wt% sulfur, from -9 wt% to ~40 wt% sulfur, from -9 wt% to ~35 wt% sulfur, from ~13 wt% to -45 wt% sulfur, from ~13 wt% to ~40 wt% sulfur, from ~13 wt% to ~35 wt% sulfur, from -16 wt% to ~45 wt% sulfur, from -16 wt% to -40 wt% sulfur, or from -16 wt% to ~35 wt% sulfur, based on a total weight of the polysulfide; in particular from -9 wt% to -45 wt% sulfur, from -16 wt% to ~40 wt% sulfur, or from -9 to -35 wt% sulfur, based on a total weight of the poly sulfide).

[0054] Some non-limiting examples of polysulfide compounds satisfying such standards can include, but are not necessarily limited to, sulfurized olefins, sulfurized vegetable-based fatty acids, sulfurized fatty acid C1-C4 alkyl esters, or combinations thereof (each of which may represent commercially available polysulfides).

[0055] Additional or alternative non-limiting examples of polysulfide compounds satisfying such standards can include, but are not necessarily limited to, reaction products of elemental sulfur and one or more unsaturated hydrocarbon and / or oxygen heteroatom-containing hydrocarbon compounds. In particular, such reaction products can comprise substantially no residual mercaptan content (e.g., measurable by silver titration) and / or substantially no residual ethoxylate content (e.g., as measurable by *H NMR) (in some embodiments, the presence of ethoxylates can be typical of a sulfidation mechanism for quenching residual mercaptans that may not fully disappear when a thiolated reactant is treated with elemental sulfur, as can be found in such commercially available polysulfides as TPS32 from Arkema, instead of unsaturated reactant, as can be typical of the poly sulfide collectors according to this disclosure).

[0056] In such non-limiting examples, the one or more unsaturated hydrocarbon and / or oxygen heteroatom-containing hydrocarbon compounds can comprise limonene, myrcene, ethylidene norbomene, vinyl norbomene, di cyclopentadiene, pine oil, tall oil, soybean oil, C10-C16 olefins, Cl 1 -Cl 8 unsaturated fatty acids and / or C1-C4 alkyl esters, or a combination thereof (in particular limonene, dicyclopentadiene, soybean oil, propylene tetramer, butylene trimer, Cl 1- C18 unsaturated fatty acids and / or C1-C4 alkyl esters, or a combination thereof; alternatively in particular propylene tetramer, butylene trimer, Cl 1 -Cl 8 unsaturated fatty acids and / or C1-C4 alkyl esters, or a combination thereof). Further additionally or alternatively, with respect to such reaction products, the sulfurization reaction can occur, in particular in the absence of a catalyst such as an amine catalyst, e.g., at a temperature ranging from about 125°C to about 225°C e.g., from about 125°C to about 200°C, from about 125°C to about 190°C, from about 125°C to about 185°C, from about 130°C to about 225°C, from about 130°C to about 200°C, from about 130°C to about 190°C, from about 130°C to about 185°C, from about 140°C to about 225°C, from about 140°C to about 200°C, from about 140°C to about 190°C, or from about 140°C to about 185°C; in particular from about 125°C to about 225°C, from about 130°C to about 200°C, or from about 140°C to about 185°C) for a time period from about 5 minutes to about 1 day (e.g, from about 5 minutes to about 16 hours, from about 5 minutes to about 12 hours, from about 5 minutes to about 10 hours, from about 5 minutes to about 8 hours, from about 5 minutes to about 6 hours, from about 5 minutes to about 4 hours, from about 10 minutes to about 1 day, from about 10 minutes to about 16 hours, from about 10 minutes to about 12 hours, from about 10 minutes to about 10 hours, from about 10 minutes to about 8 hours, from about 10 minutes to about 6 hours, from about 10 minutes to about 4 hours, from about 15 minutes to about 1 day, from about 15 minutes to about 16 hours, from about 15 minutes to about 12 hours, from about 15 minutes to about 10 hours, from about 15 minutes to about 8 hours, from about 15 minutes to about 6 hours, from about 15 minutes to about 4 hours, from about 30 minutes to about 1 day, from about 30 minutes to about 16 hours, from about 30 minutes to about 12 hours, from about 30 minutes to about 10 hours, from about 30 minutes to about 8 hours, from about 30 minutes to about 6 hours, or from about 30 minutes to about 4 hours; in particular from about 5 minutes to about 1 day, from about 10 minutes to about 12 hours, or from about 15 minutes to about 8 hours).

[0057] Additional Collector(s)

[0058] To complement and / or to provide additional collecting functionality in separation methods (such a froth flotation), to control mineral / metal selectivity, and / or for various other reasons, it may be desirable to supplement the collector formulation comprising the polysulfide collector disclosed herein with one or more additional collectors. In other embodiments, the collector formulation may contain substantially no additional collectors (or no intentionally added additional collectors), other than the polysulfide collector disclosed herein - for the purposes of this disclosure, a collector component made so as to encompass both a polysulfide fitting the relatively long sulfur chain description herein as well as a polysulfide containing only shorter sulfur chains (broadly, n < 3, but, when polysulfide collector n is at least 4, n < 4) shall not have the portion of the component containing shorter sulfur chains considered an “additional collector” herein. Non-limiting examples of additional collectors can include one or more of xanthates, xanthate esters, xanthogen formates, dithiophosphates, monothiophosphates, dithiophosphinates, dithiocarbamates, mercaptobenzothiazoles, thionocarbamates, or combinations thereof. Nonlimiting examples of specific compounds can include, but are not necessarily limited to, ethyl xanthate, butyl xanthate, sodium isobutyl xanthate (SIBX), potassium amyl xanthate (PAX), sodium di-ethyldithiophosphate, isobutyl dithiophosphate (IBDP), potassium di-isobutyl dithiophosphate, potassium di-sec-butyl dithiophosphate, diisobutyl monothiophosphate, sodium dicresyl dithiophosphate, sodium dicresyl monothiophosphate, sodium diisobutyl dithiophosphinate, sodium isobutyl dithiophosphinate, potassium n-decyl dithiocarbamate, isopropyl ethylthionocarbamate (IPETC), O-isopropyl thionocarbamates, and the like, and combinations thereof. Some tradenames of note can include, but are not necessarily limited to, AEROPHINE™ 3418A (Solvay / Syensqo), AERO™ 8989 (Solvay / Syensqo), and the like.

[0059] Additionally or alternatively, when an additional collector is present, the collector may comprise linear primary mercaptans such as n-dodecyl mercaptan (NDM), branched tertiary mercaptans such as tert-dodecyl mercaptan (TDM), other thiolated (mercaptized) C4-C8 olefins (such as sold under the tradename TPS44 from Arkema), other thiolated (mercaptized) C10-C16 olefins (such as sold under the tradename TPS20 from Arkema), or combinations thereof.

[0060] Further additionally or alternatively, when an additional collector is present, the additional collector may comprise, consist of, or consist essentially of at least one C6-C12 branched or straight chained alkane(s) and / or at least one branched or straight chained C6-C14 alkene, particularly dodecane, dodecene, and / or tetradecene.

[0061] Still further additionally or alternatively, when an additional collector is present, the collector may comprise, consist of, or consist essentially of one or more of the collectors described in U.S. Serial No. 63 / 434,110, the disclosure of which is incorporated by reference herein in its entirety for all purposes, but in particular for its disclosure relevant to the following collectors:

[0062] 1) a combination of at least one mercaptan (a) having a structure i) and / or ii): where R8and R9are independently selected from branched or straight chain C1-C23 alkyl groups, or from Cl -Cl 8, more preferably from Cl -Cl 5, or from Cl -CIO alkyl groups; and where R10is a C6-C24, or C6-C20, more preferably C6-C16, particularly C6-C14 branched alkyl group; wherein an average number of carbon groups in the a) mercaptan is from 6 to 24, or from 6-19, more preferably from 6-16, or from 6-14, where preferably a) is 2-butyl-l -octanethiol, 2- dodecanethiol and / or 2-ethyl-l -decanethiol; and one or more aromatic, aliphatic or polyalkylene oxide compounds (b) comprising from 4 to 100 carbon atoms, and having one or two -OH groups, particularly polypropylene glycol, pine oil, cresylic acid, and / or methyl isobutyl carbinol;

[0063] 2) at least one sulfide (c) having a structure Ru-S-R12, where R11and R12are independently selected from Cl -Cl 6, or Cl -Cl 4, or Cl -Cl 2, particularly Cl -CIO straight chain and branched alkyl groups, wherein an average number of carbons in the (c) sulfide is from 10- 24, or from 12-22, or from 12-20, particularly from 14-18; and / or

[0064] 3) a combination of at least one trithiocarbonate (d) having a structure: , r salt thereof; or combination thereof, where R13and R14are independently selected from branched or straight chain C1-C23 alkyl groups, preferably from C1-C18, more preferably from C1-C15, most preferably from Cl -CIO alkyl groups, wherein an average number of carbon groups in the mercaptan is from 6 to 24, preferably from 6-19, more preferably from 6-16, most preferably from 6-14; and where R15is a C6-C24 branched alkyl group, preferably C6-C20, more preferably C6-C16, most preferably C6-C14, branched alkyl group; and one or more aromatic, aliphatic or polyalkylene oxide compounds (e) comprising, consisting of, or consisting essentially of from 4 to 100 carbon atoms, and having one or two - OH groups.

[0065] In collectors (1) and (3), it is noted that the one or more aromatic, aliphatic or polyalkylene oxide compounds (b) and (e), respectively likely would be characterized as dispersants (and / or as frothers / surfactants) herein. To the extent that these are incorporated by reference from another publication, as noted above, they are listed here, but, to the extent that compounds (b) and (e) are characterized differently according to this disclosure, their listing in this section does not overrule their identification as a separate functional component from the colisted “additional collector(s)” according to this disclosure.

[0066] When present, mixtures and / or reaction products of any of these aforementioned additional collectors are also contemplated.

[0067] Depressants

[0068] As used herein, a “depressant” is a compound that selectively reacts and / or complexes (physically and / or chemically associates) with certain minerals or ore components (usually particulate in a slurry medium), causing them to phase separate from other (usually particulate) minerals or ore components (e. , to sink in slurry / emulsion and / or gravity-based separations, whether or not assisted by other separation means that can include but are not necessarily limited to centrifugation), usually by increasing hydrophilicity of the certain minerals or ore components, relative to the other surrounding minerals or ore components.

[0069] Depressants may be most useful when the ore to be separated is or substantially comprises a concentrate, where one or a number of initial separations has already been conducted to isolate out the undesirable components of a raw ore, as depressants that increase hydrophilicity can typically be chosen to enable a more specific selectivity toward one or more undesirable minerals / metals, such that they can specifically avoid being collected, e.g., in froth flotation. As such, when the ore to be separated is not a concentrate and / or is (or is closer to) a raw ore, depressants for one or more undesirable / less desirable minerals may be relatively ineffective and / or may complicate retrieval of sulfide (or other, such as “free”) minerals, such as by froth flotation. Thus, in certain circumstances such as when sulfide minerals are being separated, e.g., by froth flotation, it may be desired to use a Fe depressant, as iron is neither precious nor semiprecious and is thus rarely one of the desired minerals to collect. A non-limiting example of a Fe depressant can include dextrin, or the like. In some alternative embodiments, substantially no depressants (or substantially no Fe depressants) may be used in the introduction and / or separating steps.

[0070] Dispersants for the Collectors / Depressants

[0071] In some circumstances, such as when a polysulfide collector, optional additional collector, and / or optional depressant may have poor compatibility with the (aqueous) slurry medium, a dispersant may be included in the collector formulation, such as to specifically address that compatibility issue. In alternative circumstances, substantially no dispersant may be used in the introduction and / or separating steps.

[0072] The dispersant, when present, can advantageously bridge the compatibility gap between the specific collector(s) and / or optional depressant(s) in the collector formulation and the desirable mineral(s) in the ore to be collected. Non-limiting examples of such dispersants may include, but are not necessarily limited to, components (b) and / or (e) as mixed with the additional collectors ( .e., one or more aromatic, aliphatic or polyalkylene oxide compounds comprising from 4 to 100 carbon atoms, and having one or two -OH groups), 2-ethylhexanol (2EH), oligo / poly alkylene oxides (including homopolymers and block copolymers of different alkylene units, such as ethylene oxide / glycol and propylene oxide / glycol for example), and the like, and combinations thereof.

[0073] In some circumstances, compounds characterized herein as dispersants may also secondarily function as frothers / surfactants. However, at least as used herein, a compound acting primarily as a dispersant can typically be added with the collector formulation or shortly before or thereafter, while a compound acting primarily as a frother / surfactant can typically be added separately, at the time of the gas sparging step or shortly before or shortly thereafter. Additionally or alternatively, as known to an artisan of ordinary skill, it may also be possible to distinguish a compound meant to act primarily as a dispersant from the same compound meant to act primarily as a frother / surfactant by the amount in which it is added. Diluents for the Collectors

[0074] Although the polysulfide collectors (and optionally the additional collectors, when present) can be liquids at room (and other relevant) temperature(s), they can alternatively be solids. Even when liquid, their viscosity may be undesirably / relatively high.

[0075] Therefore, in some circumstances including but not limited to solid / high viscosity collector situations, a diluent may be added to dissolve / solubilize the collector(s) and / or to reduce their viscosity, e.g., to make them more facile within the separation methods disclosed herein. In alternative circumstances, substantially no diluent may be used in the introduction and / or separating steps.

[0076] Due to the organic nature of the collector(s) disclosed herein and the viscosity of the (aqueous) medium, such diluent(s), when added, may often be organic / hydrocarbon in nature. Although they may possess a desired function similar and / or complementary to the optional dispersant(s) disclosed herein, their specific lack of heteroatoms / polar functionality distinguishes them from dispersants herein.

[0077] Non-limiting examples of such diluents can include, but are not necessarily limited to, predominantly hydrocarbon-based compounds such as paraffins / waxes, naphtha, kerosene, (unadditized) motor gasoline, (unadditized) diesel fuel, (unadditized) jet fuel, light fuel oil, intermediate-cut fuel oil, (unadditized engine and / or transmission) lubricant oil, and the like, and combinations thereof. pH Modifiers

[0078] In some circumstances, it may be desirable to control a pH of the ore / mineral slurry in the (aqueous) medium. One potential reason to control the pH is to enable a more selective and / or more efficient separation of mineral(s) in the ore(s), e.g., because of the physico-chemical and / or electro-chemical condition of the ore(s) to be separated, the (aqueous) medium, or the slurry thereof and / or to improve the activity / selectivity of the collector formulation in the medium / slurry. In alternative circumstances, a pH of the ore / mineral slurry in the (aqueous) medium may be allowed to naturally develop / coalesce, without specific control and thus in the absence of added pH modifier. When a pH is controlled, such as in froth flotation, it can typically be controlled to be somewhat basic, e.g., from above 7 to 13, from above 7 to 12, from above 7 to 11, from above 7 to 10, from above 7 to 9, from 8 to 13, from 8 to 12, from 8 to 11, from 8 to 10, from 9 to 13, from 9 to 12, from 9 to 11, from 9 to 10, from 10 to 13, from 10 to 12, from 10 to 11, or from 11 to 13 (in particular, from above 7 to 12, from 8 to 12, or from 9 to 11). As a result of the basicity that can typically be desired, one way to control the pH is through addition of a basic compound, whether in the collector formulation or separately (regardless of togetherness or separateness, any pH modifier can typically be considered not to be a component of the collector formulation herein). While there are many basic compounds, non-limiting examples of a basic pH modifier can include, but are not necessarily limited to, ammonium hydroxide, lithium hydroxide, sodium hydroxide, potassium hydroxide, magnesium hydroxide, calcium hydroxide, magnesium oxide-hydroxide, calcium oxide-hydroxide, guanidine, sodium cyanide, potassium cyanide, and combinations thereof. In certain embodiments, the pH modifier can specifically not comprise sodium or potassium cyanide. Typically, a basic pH modifier can comprise a hydroxyl group and an alkali and / or alkali earth metal (e.g., comprising lithium, sodium, potassium, calcium, or a combination thereof; in particular comprising sodium, potassium, or a combination thereof).

[0079] Alternatively, a pH modifier can include an acidic compound, such as an inorganic acid (e.g., hydrochloric acid, nitric acid, phosphoric acid, a mono-metal di-hydrogen phosphate, a dimetal mono-hydrogen phosphate, sulfuric acid, a mono-metal mono-hydrogen sulfate, carbonic acid, a mono-metal mono-hydrogen carbonate, boric acid, a mono-metal di-hydrogen borate, a dimetal mono-hydrogen borate, or the like, or combination thereof) or an organic acid (e.g., methanesulfonic acid, benzenesulfonic acid, toluenesulfonic acid, 2-aminoethanesulfonic acid, benzoic acid, salicylic acid, formic acid, acetic acid, fluoroacetic acid, trifluoro acetic acid, butyric acid, citric acid, lactic acid, tartaric acid, or the like, or combinations thereof), or a combination thereof.

[0080] Frothers / Surfactants

[0081] In order to form the bubbles necessary for flotation separation, the process may typically involve sparging the slurry with a gas. The gas may comprise or be nitrogen or air; in particular, the gas may comprise or be nitrogen. If necessary or desired to stabilize the gas bubbles and / or to make them more hydrophobic in the (aqueous) medium, one or more frothers / surfactants or organic heteropolar compounds may be added, e.g., to lower the medium surface tension and / or to reinforce the surface tension of the gas bubble within the medium. In alternative circumstances, substantially no frother(s) / surfactant(s) may be used in the introduction and / or separating steps.

[0082] Non-limiting examples of frothers can include, but are not necessarily limited to, methyl isobutyl carbinol (MIBC), 2-ethylhexanol (2EH), oligo / poly alkylene oxides (including homopolymers and block copolymers of different alkylene units, such as ethylene oxide / glycol and propylene oxide / glycol for example), and the like, and combinations thereof.

[0083] Ore(s) / Mineral(s) to be Separated

[0084] Although the compositions and methods disclosed herein may be generically used to separate any of a variety of desired ores and / or minerals out from others (and / or gangue), a specific ore to be separated may comprise a Cu-bearing and / or Au-bearing mineral, with the collector selectively targeted to assist the Cu-bearing, Au-bearing, Mo-bearing, and / or Ag-bearing mineral(s) to phase separate in the separation step. In froth flotation, the phase separation may be to associate with hydrophobic bubbles, against the action of gravity, with the assistance of a collector formulation (among other optional additives) and to thus be collected from an upper surface of the mineral slurry, leaving less desirable and / or undesirable ore component within the slurry medium and / or to drop out by sinking (e.g., optionally with the assistance of a depressant) within the slurry medium (e.g., to the bottom, under the action of gravity).

[0085] In particular, the ore to be separated may comprise a Cu-bearing mineral and / or an Au- bearing mineral. The Cu-bearing mineral may comprise at least one of chalcopyrite (CuFeS ), bornite (CusFeS^, covellite (CuS), chalcocite (Cu?S), and a combination thereof; in particular comprising chalcopyrite. The Au-bearing mineral may comprise “free” gold (Au), silver-gold, gold pyrite (AujS). a gold telluride such as calaverite (AuTe ) and / or potash-zinc ore (AuAgTe4), gold mayenite, gold arsenopyrite, iron oxide copper gold ore, and combinations thereof.

[0086] Although ores from various places may contain different ratios of metal-bearing minerals, when both are present, a weight ratio of Cu-bearing mineral(s) to Au-bearing mineral(s) in the disclosed method(s) can be from about 5:1 to about 100000:1 w / w (e.g., from about 5:1 to about 50000:1, from about 5:1 to about 30000:1, from about 5:1 to about 20000:1, from about 5:1 to about 10000:1, from about 5:1 to about 7500:1, from about 5:1 to about 5000:1, from about 5:1 to about 2500:1, from about 5:1 to about 1000:1, from about 5:1 to about 500:1, from about 5:1 to about 250:1, from about 5:1 to about 100:1, from about 10:1 to about 100000:1, from about 10:1 to about 50000:1, from about 10:1 to about 30000:1, from about 10:1 to about 20000:1, from about 10:1 to about 10000:1, from about 10:1 to about 7500:1, from about 10:1 to about 5000:1, from about 10:1 to about 2500:1, from about 10:1 to about 1000:1, from about 10:1 to about 500:1, from about 10:1 to about 250:1, from about 10:1 to about 100:1, from about 50:1 to about 100000:1, from about 50:1 to about 50000:1, from about 50:1 to about 30000:1, from about 50:1 to about 20000:1, from about 50:1 to about 10000:1, from about 50:1 to about 7500:1, from about 50:1 to about 5000:1, from about 50:1 to about 2500:1, from about 50:1 to about 1000:1, from about 50:1 to about 500:1, from about 50:1 to about 250:1, from about 100:1 to about 100000:1, from about 100:1 to about 50000:1, from about 100:1 to about 30000:1, from about 100:1 to about 20000:1, from about 100:1 to about 10000:1, from about 100:1 to about 7500:1, from about 100:1 to about 5000:1, from about 100:1 to about 2500:1, from about 100:1 to about 1000:1, from about 100:1 to about 500:1, from about 500:1 to about 100000:1, from about 500:1 to about 50000:1, from about 500:1 to about 30000:1, from about 500:1 to about 20000:1, from about 500:1 to about 10000:1, from about 500:1 to about 7500:1, from about 500:1 to about 5000:1, from about 500:1 to about 2500:1, from about 1000:1 to about 50000:1, from about 1000:1 to about 30000:1, from about 1000:1 to about 20000:1, from about 1000:1 to about 10000:1, from about 1000:1 to about 7500:1, or from about 1000:1 to about 5000:1).

[0087] Non-limiting examples of ores and / or minerals that may be separated using the depressant disclosed herein are those that may include both Cu and Au. Additionally or alternatively, the ore(s) and / or mineral(s) may comprise Fe, Te, and / or Mo. It should be understood that these minerals may include mixtures of minerals, e.g., the Cu may be in one mineral and the Au may be in another mineral. Thus, the present method may recover as much Cu and Au as possible, and optionally Ag when present, from all other minerals (such as iron oxides / sulfide, carbonates, silicates, aluminates, combinations / co-products thereof, and / or other lower value minerals such as clays, etc.). In addition, Mo alone and / or Cu-Mo minerals may be recovered. The main targets can be Mo and Au when they are present with Cu and / or Ag, such that valuable streams of Mo, Au, Ag and / or Cu may be recovered. Non limiting examples of ores that may be separated by use of the present method can include, but are not necessarily limited to, chalcopyrite (CuFeSi), bornite (CusFeS4), covellite (CuS), chalcocite (CU2S), “free” gold (Au), silver-gold, gold pyrite (AU2S), a gold telluride such as calaverite (AuTe2) and / or potash-zinc ore (AuAgTe4), gold mayenite, gold arsenopyrite, iron oxide copper gold ore, and molybdenite (M0S2). The relative ratios of copper to gold, copper to molybdenum, silver to gold, and / or gold to molybdenum, in various embodiments, may be from 60:40 to 99.999:0.001 by weight (e.g., from 70:30 to 99.999:0.001 by weight, from 80:20 to 99.999:0.001 by weight, from 90: 10 to 99.999:0.001 by weight, from 95:5 to 99.999:0.001 by weight, from 99:1 to 99.999:0.001 by weight, from 99.9:0.1 to 99.999:0.001 by weight, from 60:40 to 99.99:0.01 by weight, from 70:30 to 99.99:0.01 by weight, from 80:20 to 99.99:0.01 by weight, from 90:10 to 99.99:0.01 by weight, from 95:5 to 99.99:0.01 by weight, or from 99:1 to 99.99:0.01 by weight).

[0088] In various embodiments, the ore to be separated can include, but are not necessarily limited to, sulfide minerals and / or precious metals based on one or more of Cu, Mo, Pb, Zn, Ni, Co, Fe, As, Mg, Cd, Pd, Pt, Ru, Ir, Os, Te, Au, and Ag (in particular, based on Cu, Mo, Fe, Au, Ag, or a combination thereof).

[0089] Methods for Separation

[0090] A method for separation of minerals in an ore, e.g., by (froth) flotation, is provided. The method can comprise: (A) introducing into a separation apparatus (i) a slurry comprising (appropriately sized particles of) the ore to be separated and an aqueous medium comprising water, and (ii) an effective amount of a collector formulation comprising the polysulfide collector according to this disclosure (and optionally comprising one or more additional collectors, a hydrocarbon diluent, a dispersant, or a combination thereof, all of which components as described in this disclosure); and (B) separating (such as via flotation, for example froth flotation) some or all of the ore into a plurality of minerals. In particular, the separation, whether directly or indirectly through one or more additional separation, purification, and / or treatment steps, can create / form a mineral concentrate.

[0091] Non-limiting examples of minerals that may be separated using collector formulations comprising the polysulfide collectors according to this disclosure can include those that can recover as much Cu and / or Mo as possible while selectively separating Fe (and other non- metallic minerals such as carbonates, silicates, etc.). Mo in general from all other minerals. In addition, Au alone or Cu-Au and Ag-Au minerals may be recovered while selectively separating Fe and other invaluable minerals. The main targets are Mo and Au when they are present with Cu or Ag. The flotation compositions disclosed herein may be used to separate Cu-Mo and / or Cu-Au and / or Au-Mo and / or Ag-Au ores. Non limiting examples of ores that may be separated by use of the flotation compositions are chalcopyrite, chalcocite, bornite, and molybdenite.

[0092] Advantageously, in particular for froth flotation, the separating step can comprise sparging the slurry with a gas, optionally but preferably comprising nitrogen (e.g., as air or a mixture of nitrogen containing less oxygen than is in air). Other (relatively inert) gases can be used in addition or instead, so long as the sparging generates bubbles (which can be made more hydrophobic, as a contrast to the hydrophilic aqueous medium, through the use of a frother / surfactant component). If desired, such as for stabilizing bubbles or for any other reason, a frother can be introduced before or during the separating step, but typically separate from the collector formulation.

[0093] In many embodiments, the collector formulation can be added to the already created slurry of the aqueous medium and the (appropriately sized particles of) the ore to be separated. However, in some embodiments, it may be desirable for the collector formulation to be added to the ore to be separated prior to formation of the slurry with the aqueous medium (“to the grind,” which includes addition immediately before, during, and / or immediately after steps to appropriately size the ore particles for slurrying).

[0094] Often, but not always, a pH of the slurry can be controlled using one or more pH modifiers, for example to be from above 7 to 13, from 8 to 12, in particular from 9 to 11. For basic pH’s, the pH of the slurry can often be controlled through addition of a basic compound, such as comprising a hydroxyl group and lithium, sodium, potassium, calcium, or a combination thereof. In some embodiments, however, acid pH’s can be targeted for control. In alternative embodiments to both acid and base control, it may be desired that the separation occur at a “natural” pH, with no particular pH control. Nevertheless, in embodiments where pH is controlled, it may be desirable to exclude sodium and / or potassium cyanide as pH modifiers, as they can potentially interfere with separations (see Example 54 below).

[0095] Thus, froth flotation separation compositions comprising an aqueous medium, optionally but generally a frother according to this disclosure, optionally a pH modifier according to this disclosure, and a collector formulation according to this disclosure are provided herein. And the froth flotation separation compositions according to this disclosure can be in a (froth flotation) separation method to separate minerals in an ore, also according to this disclosure.

[0096] Additional Embodiments

[0097] Additionally or alternatively, the invention may include, but is not necessarily limited to, the following non-limiting embodiments.

[0098] Embodiment 1. A method for separation of minerals in an ore, comprising: introducing into a separation apparatus a slurry comprising: the ore to be separated, the ore comprising sulfide minerals and / or precious metals based on one or more of Cu, Mo, Pb, Zn, Ni, Co, Fe, As, Mg, Cd, Pd, Pt, Ru, Ir, Os, Te, Au, and Ag; and an aqueous medium comprising water; and an effective amount of a collector formulation comprising a polysulfide having one or more -Sn— moieties in which n is at least 4 and wherein the polysulfide comprises from 9 wt% to 45 wt% sulfur content, in particular from 16 wt% to 40 wt%, based on a total weight of the poly sulfide, optionally an additional collector, optionally a hydrocarbon diluent, and optionally a dispersant; and separating some or all of the ore into a plurality of minerals.

[0099] Embodiment 2. The method of embodiment 1, wherein the separating step is flotation separation, and the plurality of minerals comprises a mineral concentrate.

[0100] Embodiment 3. The method of embodiment 1 or embodiment 2, wherein the separating step comprises sparging the slurry with a gas, optionally comprising nitrogen.

[0101] Embodiment 4. The method of any of embodiments 1-3, wherein the collector formulation is added to the ore to be separated prior to formation of the slurry with the aqueous medium.

[0102] Embodiment 5. The method of any of embodiments 1-4, wherein a frother is introduced before or during the separating step, but separately from the collector formulation.

[0103] Embodiment 6. The method of any of embodiments 1-5, wherein the collector formulation comprises a Fe depressant added before, during or after the polysulfide collector.

[0104] Embodiment 7. The method of any of embodiments 1-6, wherein a pH of the slurry is controlled to be from 8 to 12, in particular from 9 to 11. Embodiment 8. The method of embodiment 7, wherein the pH of the slurry is controlled through addition of a basic compound comprising a hydroxyl group and lithium, sodium, potassium, calcium, or a combination thereof.

[0105] Embodiment 9. The method of any of embodiments 1-8, wherein the polysulfide is comprised of a sulfurized olefin, a sulfurized vegetable-based fatty acid, a sulfurized fatty acid C1-C4 alkyl ester, or a combination thereof.

[0106] Embodiment 10. The method of any of embodiments 1-8, wherein the polysulfide is comprised from a reaction product of elemental sulfur and one or more unsaturated hydrocarbon and / or oxygen heteroatom-containing hydrocarbon compounds.

[0107] Embodiment 11. The method of embodiment 10, wherein the reaction product comprises substantially no residual mercaptan, for example measurable by silver titration, and / or no residual ethoxylate, for example as measurable by ’H NMR.

[0108] Embodiment 12. The method of embodiment 10 or embodiment 11, wherein the one or more unsaturated hydrocarbon and / or oxygen heteroatom-containing hydrocarbon compounds comprises limonene, myrcene, ethylidene norbomene, vinyl norbomene, dicyclopentadiene, pine oil, tall oil, soybean oil, C10-C16 olefins, Cl 1-C18 unsaturated fatty acids and / or C1-C4 alkyl esters, or a combination thereof, in particular limonene, dicyclopentadiene, soybean oil, propylene tetramer, butylene trimer, Cl 1 -Cl 8 unsaturated fatty acids and / or C1-C4 alkyl esters, or a combination thereof.

[0109] Embodiment 13. The method of any of embodiments 10-12, wherein the one or more unsaturated hydrocarbon and / or oxygen heteroatom-containing hydrocarbon compounds and the elemental sulfur are reacted, in particular in the absence of a catalyst, at a temperature ranging from about 130°C to about 200°C for a time period from about 5 minutes to about 1 day.

[0110] Embodiment 14. The method of any of embodiments 1-5 and 7-13, wherein the collector formulation consists essentially of the polysulfide collector, an additional collector, and a diluent. Embodiment 15. The method of any of embodiments 1-5 and 7-13, wherein the collector formulation consists essentially of the polysulfide collector, one or more additional collectors, and optionally a dispersant.

[0111] Embodiment 16. The method of any one of claims 1-15, wherein the ore to be separated comprises sulfide minerals and / or precious metals based on Cu, Mo, Fe, Au, Ag, or a combination thereof.

[0112] Embodiment 17. A froth flotation separation composition comprising an aqueous medium, a frother, a collector formulation, and optionally a pH modifier comprising a hydroxyl group and lithium, sodium, potassium, calcium, or a combination thereof, but comprising substantially no sodium cyanide nor potassium cyanide, the collector formulation consisting essentially of: a polysulfide having one or more -Sn- moieties in which n is at least 4 and comprising from 9 wt% to 45 wt% sulfur content, based on a total weight of the poly sulfide, wherein the poly sulfide is comprised from a reaction product of elemental sulfur and one or more unsaturated hydrocarbon and / or oxygen heteroatom-containing hydrocarbon compounds, said reactant hydrocarbon compounds comprising limonene, dicyclopentadiene, soybean oil, propylene tetramer, butylene trimer, Cl 1 -Cl 8 unsaturated fatty acids and / or C1-C4 alkyl esters, and combinations thereof; optionally an additional collector comprising n-dodecyl mercaptan, tert-dodecyl mercaptan, isopropyl ethylthionocarbamate, potassium amyl xanthate, sodium dicresyl dithiophosphate, or a combination thereof; optionally a hydrocarbon diluent comprising kerosene; optionally a dispersant comprising 2-ethylhexanol, a polyfpropylene glycol), or a combination thereof; optionally a depressant comprising dextrin;.

[0113] Embodiment 18. Use of the froth flotation separation composition according to embodiment 17 in a froth flotation separation method to separate minerals in an ore comprising sulfide minerals and / or precious metals based on Cu, Mo, Fe, Au, Ag, or a combination thereof, to form a mineral concentrate.

[0114] EXAMPLES

[0115] Preparation of Polysulfide Collectors - Examples 1-12

[0116] When not obtained, e.g., from a commercial source, in polysulfide component form, polysulfides in these Examples were prepared by reacting elemental sulfur with reactive (unsaturated and optionally oxygen-containing hydrocarbon) compounds under inert atmosphere (e.g., nitrogen gas), or in the presence of trace amounts of oxygen, at ~140°C or above.

[0117] Elemental sulfur and the reactive compound(s) at the desired composition were placed in a container equipped with a stirring device. The container was connected to a condenser to allow any gas that was not condensed and returned to the container to be caustic scrubbed for hydrogen sulfide (H2S) quenching, but only if desired. The reaction was initiated by exposing the container to specified temperatures at or above ~140°C for at least ~5 minutes but up to ~1 day (typically, —120 minutes was sufficient). The reaction was stopped by removing the container from heat, after which the sulfurized products were purged with nitrogen or exposed to vacuum, e.g., to remove residual H2S emanating from the reaction.

[0118] When necessary, purification of the sulfurized products (removal of H2S by-product dispersed in the final product as a gas) was by gas (e.g., nitrogen) sparging and / or by caustic washing. The gas sparging procedure involved a (glass) tube with frits (or a similar device) immersed in the sulfurized product(s) so as to dispense nitrogen directly thereinto. This gas sparging procedure was conducted at the reaction temperature (~140°C or above) and maintained for a few minutes to several hours, depending on the amount of H2S remaining in the sulfurized product(s). As desired, additional sparging may be applied at room temperature (~20-25°C) and / or under vacuum. The caustic washing purification involved using aqueous base solution (e.g., sodium and / or potassium hydroxide, such as in aqueous solution) to immerse the sulfurized product(s) under stirring for several minutes to hours, thus converting residual H2S, for instance, into water-compatible sodium hydrosulfide (NaSH), after which the purified sulfurized product was then separated from the aqueous base / NaSH solution via a separation funnel or centrifuge. Finally, the purified sulfurized product was optionally but preferably washed with dilute acetic acid solution (~1%, to remove base residue) and dried, typically under vacuum, to form the polysulfide collector.

[0119] Substantially complete consumption of (unsaturations in) the reactive compounds to form the polysulfide collectors were confirmed by ’H NMR analysis and / or by x-ray diffraction. For instance, the carbon-carbon double bonds in the reactive compound limonene are detected by ’H NMR, but, after reaction with sulfur, the peaks for the double bonds appear to be substantially (completely) absent. See Figure 1. Substantially complete reaction of elemental sulfur was confirmed by X-ray diffraction, which appears to show the crystalline peaks for orthorhombic sulfur, detected for elemental sulfur, were not visible for sulfurized products based on limonene and limonene / dicyclopentadiene mixtures (at ~35 wt% sulfur after reaction). See Figure 2.

[0120] Molecular characterization of sulfurized products appear to confirm that the resulting molecules were relatively low molecular weight (e.g., not polymers) as demonstrated by Gel Permeation Chromatography (GPC). A Waters 2695e instrument, coupled to a Wyatt T-rEX Differential Refractometer was used, in tandem with two PL Gel mixed E columns and a guard column (~7.8 mm I.D. x ~30 cm, ~3 pm). Solute was HPLC grade tetrahydrofuran, run at ~35°C using a flow rate of ~1 mL / min. Sample injection volume was -100 pL, with a sample concentration of -2.0 mg / mL (unfiltered). Nine polystyrene standards were used for calibration, ranging in Mp from -370 to -27,000 g / mol. Analysis using ASTRA 7 software, with calibration data fitted to a cubic polynomial with R2of at least 0.999. Number average molecular weight (Mn) and polydispersity index (PDI; ratio of weight average molecular weight, or Mw, to Mn) were obtained from GPC are shown in Table 1 below. Reaction temperatures and times utilized to achieve the indicated sulfurized product in liquid form is included in Table 1 below. Oleris® Esterol A is commercially available from Arkema.

[0121] Table 1.

[0122] Despite substantially complete reaction of elemental sulfur and reactive compound to form the sulfurized product(s), and in most cases the relatively low Mn by GPC, the products appear to retain long sulfide chains that seem to differentiate them from certain commercial products that contain only mono-, di-, and / or tri- sulfides (n = 1-3). To delve further into the - Sn- moieties in the polysulfide products, a sulfurized product made from limonene containing ~35 wt% sulfur was characterized by Raman spectroscopy. The analysis included a deconvolution into distinct peaks for monosulfides (C-S-C), disulfides (C-S-S-C), tri- / tetra- sulfides (C-S-S-S-C / C-S-S-S-S-C), and pentamer and higher (n > 4) sulfides. The analyzed spectrum is shown in Figure 3 on the left; right side focuses on the relevant sulfide wavenumbers and shows the peak deconvolution / baseline. Peak assignment for sulfurized limonene (based on Figure 3) were as follows: monosulfides at -589 cm'1; disulfides at -506 and -493 cm'1; tri- and tetra- sulfides at -464 and -430 cm'1, respectively; and higher order sulfides at — 430 cm'1. These peak assignments were also validated against Raman spectra (not shown) of well-known molecules such as elemental sulfur (Ss), dodecyl mercaptan, dioctyl sulfide, and dicyclohexyl disulfide, as well as various other commercially available mercaptans / sulfides / polysulfides.

[0123] Froth Flotation Systems with Limonene-Based Collector Formulations - Examples 13-18

[0124] Use of the sulfurized products as poly sulfide collectors for froth flotation of relevant minerals / ores was validated by floating —2 grams of chalcopyrite in a -200-ml Hallimond tube. Different collector formulations of the polysulfide based on limonene (Example 1) were evaluated as Examples 15-18, with the “control” formulations of Comparative Examples 13 and 14 containing no poly sulfide, as detailed in Table 2 below (Example 1 product is abbreviated as “SM-limonene” in Table 2).

[0125] Table 2.

[0126] The collector formulations of Examples 13-18 were tested for chalcopyrite recovery at pH values between -4 and -12. pH was controlled with an appropriate pH modifier, based on the respective pH value(s), which pH modifiers / content are not reflected in the collector formulations or component percentages thereof in Table 2. At each pH value, flotation was carried out for -5 minutes using nitrogen gas sparging at a flow rate of -40 ml / min. The chalcopyrite was ground and screened to a particle size range of -75-150 pm. Collector formulations were dosed at -4 pL (except for absent Comparative Example 13), with the frother in each case (methyl isobutyl carbinol) being dosed at -2 pL. Results can be seen in Figure 4.

[0127] Froth Flotation Systems with Various Polysulfide Collector Formulations - Examples 19-28

[0128] Hallimond tube experiments like to those in Examples 13-18 were repeated for a variety of polysulfides synthesized using the reaction described in Examples 1-12. However, upon x-ray diffraction of the chalcopyrite mineral used in these Hallimond tube experiments, the ore to be separated was determined to be only -78% chalcopyrite, with Franklinite (-15%), quartz (-4%), and pyrite (-3%) components.

[0129] In these Examples, also in contrast to previous Examples, the collector formulations containing the various polysulfide products were diluted with an equivalent amount of kerosene diluent - only the comparative collector formulation based on the potassium amyl xanthate (PAX) collector (Comparative Example 28) was used without organic diluent (the PAX collector was diluted in water and added as an aqueous solution, but, because the medium is aqueous, water added to dissolve or emulsify a component is not considered a “diluent” of the collector formulation). Also in these Examples, the pH was controlled to values from -9 to -11 using NaOH as a pH modifier, with the amount of NaOH (or solution containing same) being varied to attain each respective pH value. Table 3 below shows the collector formulation systems. As in Examples 13-18, methyl isobutyl carbinol (MIBC) was used as a frother in each case. Results are shown in Figure 5.

[0130] Table 3.

[0131] Froth Flotation Separation in Cu- / Mo- / Fe- Containing Minerals / Ore based on Limonene -based Polysulfide Collector Formulations - Examples 29-32

[0132] The following experiments were carried out in a 2.5 L Denver-type flotation cell. These experiments were performed using different collector formulations / separation systems to evaluate the impact of various collector / frother components on performance of the recovery of a mineral that was rich in copper (Cu), molybdenum (Mo) and iron (Fe).

[0133] In these Examples, ~500 g of the ore in —330 ml of water were ground in a rod mill for ~30 minutes in the presence of kerosene and varying amounts of lime (to maintain pH at ~10). The pulp was then transferred from the mill to the ~2.5 L flotation cell for testing. Different reagent combinations were added at different amounts, with percentages indicated in Table 4 being exclusive of the amount of pH modifier used to control pH. The results, as shown graphically in Figure 6, appear to show that the formulations / systems containing polysulfide collectors (Examples 30-32) improved Cu recovery and grade, as compared to a benchmark collector formulation / system containing potassium amyl xanthate (PAX). The polysulfide collector formulation including additional collector NDM and diluent kerosene appeared to show the best combination of Cu recovery and Cu grade in this grouping. In these systems, AERO™ 8989 is commercially available from Solvay / Syensqo; NDM is commercially available from Arkema; PPG 425 is polypropylene glycol) with Mw of -425 g / mole, which was obtained from Sigma-Aldrich; and PGE 9225 was an oligomeric propylene glycol ether obtained from ArrMaz.

[0134] Table 4. The results, as shown in the Cu grade versus Cu recovery graph of Figure 6, appear to show that the formulations / systems containing polysulfide collectors (Examples 30-32) improved Cu recovery and grade, as compared to benchmark collector formulations / systems. The polysulfide collector formulation including additional collector NDM and diluent kerosene appeared to show the best combination of Cu recovery (collective percentage of copper collected, relative to the amount in the ore to be separated) and Cu grade (the percentage of copper relative to other mineral components in whatever was collected) in this grouping.

[0135] Froth Flotation of Cu-Au Ore with Various Collector Formulations - Examples 33-41

[0136] Examples 33-41 involve froth flotation separation experiments a Cu-Au ore from an unidentified mine. The collector formulation system identified as “Standard” was a blend of ~1 part isopropyl ethylthionocarbamate (IPETC) to ~4 parts dithiophosphate (by weight). Total collector formulation dosage was -30 g / ton, and experiments were controlled to attain pH -9. In these experiments, polysulfide collectors according to the disclosure were substituted in equal dosage for the dithiophosphate in the “Standard” and thus the non-comparative collector formulations in these Examples each included 1 part IPETC to 4 parts of poly sulfide collector at a total dosage of collectors of ~30 g / ton of ore. DSF-004A, commercially available from Orica, was used as a frother at ~20 g / ton dosage in each Example.

[0137] In some cases, the collector formulation containing the polysulfide collector was added to the ore immediately before, during, or immediately after the sizing (crushing) of the ore to attain particle sizes suitable for slurrying (referred to as being added “to [the] grind” herein). Without being bound by theory, adding a collector formulation to the grind can allow complexation / association of the collector components with the freshly exposed ore surfaces, instead of after the slurrying of the ore with the (aqueous) medium, which can (sometimes) kinetically improve the surface modification of the ore, thereby allowing more effective / efficient separation. If no annotation is specifically made, the collector formulations were added to the already slurried ore. Collector formulations are delineated in Table 5.

[0138] Table 5.

[0139] Figure 7 graphically shows that only polysulfide based on sulfurized propylene tetramer added to the grind appeared to approximate the Cu recovery-grade curve of the Standard for this ore. In Figure 7, “Tetramer” refers to the reactant Propylene Tetramer; “EA” refers to the reactant Oleris® Esterol A; “DCPD” refers to the reactant dicyclopentadiene; and the percentage refers back to the sulfur content delineated in Table 1.

[0140] In these Examples, furthermore, adding polysulfide collector to the grind typically tended to outperform addition during conditioning (z.e., to the slurried ore). While most collector formulation additions to the slurry occurred over about a 1 minute (conditioning) time frame, certain Examples included tripling the usual exposure / conditioning period to ~3 minutes. Even with that additional exposure / conditioning, some collector formulations still preformed rather poorly (e.g., the polysulfide collector based on sulfurized dicyclopentadiene), relative to the Standard. According to Figure 7, high sulfur content in the polysulfide collector did not appear to be a simple pre-requisite for Cu recovery (noting with the polysulfide collectors based on sulfurized Oleris® Esterol A that the one with 23 wt% sulfur content performed consistently worse in this Cu-Au ore system than the one with 9 wt% sulfur content).

[0141] In addition, when assessing Fe recovery versus Cu recovery (not shown), similar performance gains were seen in adding the polysulfide collectors to the grind versus adding to the slurry. Notably, the polysulfide collectors of this disclosure seemed to recover more Fe than the Standard collector (also not shown).

[0142] Furthermore, it is noted that the Standard collector formulation appeared to attain an Au recovery of at least 95% (graphic not shown), whereas only the collector formulations containing the sulfurized Propylene Tetramer added to the grind (Example 36) and the -9 wt% sulfurized Oleris® Esterol A added to the grind (Example 38) appeared to attain more than a 50% Au recovery (-84% and -63%, respectively).

[0143] Froth Flotation of Cu Ore with Various Collector Formulations - Examples 42-53

[0144] Examples 42-53 involve froth flotation separation experiments a Cu-containing ore from an unidentified Australian mine. The collector formulation system identified as “Standard” was a dithiophosphinate (AEROPHINE™ 3418A). Total collector formulation dosage was -30 g / ton (“g / T”), unless otherwise specified, and experiments were controlled to attain pH -10. In these experiments, polysulfide collectors according to the disclosure were substituted for the dithiophosphinate in the “Standard,” although, in some Examples, a dispersant was incorporated into the collector formulation, in addition to the polysulfide collector. MIBC was used as a frother at —30 g / ton dosage in each Example.

[0145] In some cases, the collector formulation containing the polysulfide collector was added to the ore immediately before, during, or immediately after the sizing (crushing) of the ore to attain particle sizes suitable for slurrying (referred to as being added “to [the] grind” herein). Without being bound by theory, adding a collector formulation to the grind can allow complexation / association of the collector components with the freshly exposed ore surfaces, instead of after the slurrying of the ore with the (aqueous) medium, which can (sometimes) kinetically improve the surface modification of the ore, thereby allowing more effective / efficient separation. Sometimes, however (inexplicably), the collector formulation added to the slurry can outperform the one added to the grind (e.g., compare Examples 47 and 48 in Figure 8). If no annotation is specifically made, the collector formulations were added to the already slurried ore. Collector formulations are delineated in Table 6.

[0146] Table 6.

[0147] Figure 8 graphically shows that several polysulfide collector formulations appeared to approximate the Cu recovery-grade curve of the Standard for this ore, although it was noteworthy that the collector formulation containing the lower sulfur content (~9 wt%) sulfurized EA component, ~30 g / ton added to the slurry instead of to the grind (Example 46) had the best performance, and indeed even outperformed the same formulation added in slightly greater quantity to the grind (Example 47; ~35 g / ton), particularly regarding Cu grade. Also surprisingly, the collector formulations based on the sulfurized Propylene Tetramer (Examples 43-45) behaved similarly regardless of whether added to slurry or grind, and even regardless of addition of PPG dispersant.

[0148] In Figure 8, “Tetramer” refers to the reactant Propylene Tetramer; “EA” refers to the reactant Oleris® Esterol A, in which the “9%” and “23 %” refer back to the sulfur content delineated in Table 1.

[0149] In addition, when assessing Fe recovery versus Cu recovery (not shown), similar performance gains were seen in adding the polysulfide collectors to the grind versus adding to the sluny. Surprisingly, however, the same ~9 wt% sulfurized EA collector (Example 46; added to slurry, not grind) that exhibited superior performance on the Cu grade-recovery curve also exhibited a higher selectivity against Fe than the Standard collector (also not shown).

[0150] Froth Flotation of Cu Ore with Various Collector Formulations - Example 54

[0151] In this Example, froth flotation separation was conducted on a Cu-containing ore from a mine in Queensland, Australia. In this separation, an initial carbon pre-float was conducted using sodium cyanide (NaCN), prior to froth flotation separation. The collector formulation system identified as “Standard” for the froth flotation separation was a sodium isobutyl xanthate (SIBX), with dextrin included as an Fe depressant. Total collector formulation dosage was ~80 g / ton (“g / T”), and experiments were performed with “natural” (uncontrolled) pH. In these experiments, polysulfide collectors according to the disclosure were substituted for the SIBX in the “Standard.”

[0152] The results for this separation, trying various polysulfide collectors according to the disclosure (in addition to the dextrin depressant), were discouraging. Nothing performed well. Because of the pre-float in this process, there was not an option to try adding any collector formulations to the grind. Without being bound by theory, it may have been that the sodium cyanide in the pre-float may have had a negative impact on the complexation / association of the polysulfide collectors on this particular ore.

[0153] Froth Flotation of Cu-Au Ore with Various Collector Formulations - Examples 55-64

[0154] In these experiments, froth flotation separation was conducted on a Cu- and Au- containing ore from a mine in Queensland, Australia. The collector formulation system identified as “Standard” was a combination of isopropyl ethylthionocarbamate (IPETC) and potassium amyl xanthate (PAX). Total collector formulation dosage was ~13 g / ton, and experiments were performed with “natural” (uncontrolled) pH. In these experiments, polysulfide collector formulations according to the disclosure were substituted for the IPETC in the “Standard” at a dosage of ~3 g / ton, although, in some Examples, a dispersant was incorporated into the collector formulation, in addition to the poly sulfide collector. Interfroth™ IF50, commercially available from Interchem, was used as a frother at ~28 g / ton dosage in each Example. In some cases, the collector formulation containing the polysulfide collector was added to the ore immediately before, during, or immediately after the sizing (crushing) of the ore to attain particle sizes suitable for slurrying (referred to as being added “to [the] grind” herein). If no annotation is specifically made, the collector formulations were added to the already slurried ore. Collector formulations are delineated in Table 7.

[0155] Table 7.

[0156] Figure 9 graphically shows that each polysulfide collector formulation appeared to approximate the cumulative Cu recovery-grade curve of the Standard for this ore, although it was noteworthy that the collector formulations containing the lower sulfur content (~9 wt%) sulfurized EA component outperformed the Standard in Cu recovery, while the higher sulfur content (~23 wt%) sulfurized EA component outperformed all collectors with respect to cumulative Cu grade. Notably, the collector formulations containing Polypropylene glycol) dispersant seemed to enable additional Cu recovery / grade performance gains for this ore.

[0157] In Figure 9 “Tetramer” refers to the reactant Propylene Tetramer; “EA” refers to the reactant Oleris® Esterol A, in which the “9%” and “23 %” refer back to the sulfur content delineated in Table 1; and “2EH” refers to 2-ethylhexanol dispersant.

[0158] Also notably, when assessing Fe recovery versus Cu recovery (not shown), the collector formulations containing the lower sulfur content (~9 wt%) sulfurized EA component outperformed the Standard and exhibited superior selectivity against Fe. And when assessing performance regarding Au, the same ~9 wt% sulfurized EA collector also exhibited almost 90% Au recovery, which approximated that of the Standard collector (also not shown).

[0159] Froth Flotation of Cu-Au Ore with Various Collector Formulations - Examples 65-70 In these experiments, froth flotation separation was conducted on a Cu- and Au- containing ore from a mine in New South Wales, Australia. The collector formulation system identified as “Standard” was a combination of isopropyl ethylthionocarbamate (IPETC), isobutyl dithiophosphate (IBDP), and potassium amyl xanthate (PAX). Total collector formulation dosage was -24.5 g / ton, and experiments were controlled to attain pH ~8. In these experiments, polysulfide collector formulations according to the disclosure were substituted for the IBDP in the “Standard” at a dosage of ~15 g / ton, although, in one Example, a dispersant was incorporated into the collector formulation, in addition to the polysulfide collector. Interfroth™ IF6810B, which was obtained from Interchem, was used as a frother at -50 g / ton dosage in each Example.

[0160] In all cases other than the Standard, the collector formulation containing the polysulfide collector was added to the ore immediately before, during, or immediately after the sizing (crushing) of the ore to attain particle sizes suitable for slurrying (referred to as being added “to [the] grind” herein). If no annotation is specifically made, the collector formulations were added to the already slurried ore. Collector formulations are delineated in Table 8.

[0161] Table 8. Figure 10 graphically shows that each polysulfide collector formulation, when added to the grind, appeared to approximate the Fe and Cu recoveries of the Standard for this ore, although it was noteworthy that the sulfurized Propylene Tetramer poly sulfide collector appeared to show the highest selectivity against Fe (even better than the Standard) when recoveries are about 85% or below. All polysulfide collectors seemed to exhibit roughly the same Au recovery as the standard, in the 80-83% range.

[0162] In Figure 10, “Tetramer” refers to the reactant Propylene Tetramer; “EA” refers to the reactant Oleris® Esterol A, in which the “9%” and “23%” refer back to the sulfur content delineated in Table 1; and “2EH” refers to 2-ethylhexanol dispersant.

[0163] Froth Flotation of Cu-Au Ore with Various Collector Formulations - Examples 71-79

[0164] In these experiments, froth flotation separation was conducted on a Cu- containing ore from a mine in Queensland, Australia. The collector formulation system identified as “Standard” was a combination of isopropyl ethylthionocarbamate (IPETC) and isobutyl dithiophosphate (IBDP). Total collector formulation dosage was ~35 g / ton, and experiments were controlled to attain pFI ~11. In these experiments, polysulfide collector formulations according to the disclosure were substituted for the IBDP in the “Standard” at a dosage of ~30 g / ton, although, in some Examples, a dispersant was incorporated into the collector formulation, in addition to the polysulfide collector. In addition, Polyfroth W34, commercially available from Indorama, was used as a frother at ~20 g / ton dosage in each Example.

[0165] In some cases, the collector formulation containing the polysulfide collector was added to the ore immediately before, during, or immediately after the sizing (crushing) of the ore to attain particle sizes suitable for slurrying (referred to as being added “to [the] grind” herein). If no annotation is specifically made, the collector formulations were added to the already slurried ore. Collector formulations are delineated in Table 9.

[0166] Table 9.

[0167] Figure 11 graphically shows that each poly sulfide collector formulation appeared to perform almost as well as the Standard for this ore, with slightly lower Cu recoveries but also with lower Fe recoveries, indicating favorable selectivity against Fe in comparison to the Standard. In addition, particularly with respect to the sulfurized Polypropylene Tetramer polysulfide collector, the PPG dispersant seemed to markedly improve Cu recovery with roughly equivalent Fe recovery (thereby appearing to show enhanced selectivity against Fe).

[0168] In Figure 11, “Tetramer” refers to the reactant Propylene Tetramer; “EA” refers to the reactant Oleris® Esterol A, in which the “9%” and “23 %” refer back to the sulfur content delineated in Table 1; and “2EH” refers to 2-ethylhexanol dispersant.

[0169] Within this specification, embodiments have been described in a way which enables a clear and concise specification to be written, but it is intended and will be appreciated that embodiments may be variously combined or separated without departing from the invention. For example, it will be appreciated that all preferred features described herein are applicable to all aspects of the invention described herein.

[0170] In some embodiments, the invention herein can be construed as excluding any element or process step that does not materially affect the basic and novel characteristics of the compositions, methods for making the compositions, methods for using the compositions, and articles prepared from the compositions. Additionally, in some embodiments, the invention can be construed as excluding any element or process step not specified herein.

[0171] Although the invention is illustrated and described herein with reference to specific embodiments, the invention is not intended to be limited to the details shown. Rather, various modifications may be made in the details within the scope and range of equivalents of the claims and without departing from the invention.

[0172] In some embodiments, the invention herein can be construed as excluding any element or process step that does not materially affect the basic and novel characteristics of the compositions, methods for making the compositions, methods for using the compositions, and articles prepared from the compositions. Additionally, in some embodiments, the invention can be construed as excluding any element or process step not specified herein.

[0173] Although the invention is illustrated and described herein with reference to specific embodiments, the invention is not necessarily intended to be limited to the details shown. Rather, various modifications may be made in the details within the scope and range of equivalents of the claims and without departing from the invention.

Claims

CLAIMSWhat is claimed is:

1. A method for separation of minerals in an ore, comprising: introducing into a separation apparatus a slurry comprising: the ore to be separated, the ore comprising sulfide minerals and / or precious metals based on one or more of Cu, Mo, Pb, Zn, Ni, Co, Fe, As, Mg, Cd, Pd, Pt, Ru, Ir, Os, Te, Au, and Ag; and an aqueous medium comprising water; and an effective amount of a collector formulation comprising a polysulfide having one or more -Sn- moieties in which n is at least 4 and wherein the polysulfide comprises from 9 wt% to 45 wt% sulfur content, in particular from 16 wt% to 40 wt%, based on a total weight of the polysulfide, optionally an additional collector, optionally a hydrocarbon diluent, and optionally a dispersant; and separating some or all of the ore into a plurality of minerals.

2. The method of claim 1, wherein the separating step is flotation separation, and the plurality of minerals comprises a mineral concentrate.

3. The method of claim 1 or claim 2, wherein the separating step comprises sparging the slurry with a gas.

4. The method of claim 3, wherein the gas comprises nitrogen.

5. The method of any of claims 1-4, wherein the collector formulation is added to the ore to be separated prior to formation of the slurry with the aqueous medium.

6. The method of any of claims 1-5, wherein a frother is introduced before or during the separating step, but separately from the collector formulation.

7. The method of any of claims 1 -6, wherein the collector formulation comprises a Fe depressant added before, during or after the polysulfide collector.

8. The method of any of claims 1-7, wherein a pH of the slurry is controlled to be from 8 to 12.

9. The method of claim 8, wherein the pH of the slurry is controlled to be from 9 to 11.

10. The method of claim 8 or claim 9, wherein the pH of the slurry is controlled through addition of a basic compound comprising a hydroxyl group and lithium, sodium, potassium, calcium, or a combination thereof.

11. The method of any of claims 1-10, wherein the poly sulfide is comprised of a sulfurized olefin, a sulfurized vegetable-based fatty acid, a sulfurized fatty acid C1-C4 alkyl ester, or a combination thereof.

12. The method of any of claims 1-10, wherein the polysulfide is comprised from a reaction product of elemental sulfur and one or more unsaturated hydrocarbon and / or oxygen heteroatomcontaining hydrocarbon compounds.

13. The method of claim 12, wherein the reaction product comprises substantially no residual mercaptan, for example measurable by silver titration, and / or no residual ethoxylate, for example as measurable by ’H NMR.

14. The method of claim 12 or claim 13, wherein the one or more unsaturated hydrocarbon and / or oxygen heteroatom-containing hydrocarbon compounds comprises limonene, myrcene, ethylidene norbomene, vinyl norbomene, dicyclopentadiene, pine oil, tall oil, soybean oil, C10- C16 olefins, C11-C18 unsaturated fatty acids and / or C1-C4 alkyl esters, or a combination thereof, in particular limonene, dicyclopentadiene, soybean oil, propylene tetramer, butylene trimer, Cl 1 -Cl 8 unsaturated fatty acids and / or C1-C4 alkyl esters, or a combination thereof.

15. The method of any of claims 12-14, wherein the one or more unsaturated hydrocarbon and / or oxygen heteroatom-containing hydrocarbon compounds and the elemental sulfur are reacted, in particular in the absence of a catalyst, at a temperature ranging from about 130°C to about 200°C for a time period from about 5 minutes to about 1 day.

16. The method of any of claims 1-5 and 7-15, wherein the collector formulation consists essentially of the poly sulfide collector, an additional collector, and a diluent.

17. The method of any of claims 1-5 and 7-15, wherein the collector formulation consists essentially of the poly sulfide collector, one or more additional collectors, and optionally a dispersant.

18. The method of any one of claims 1-17, wherein the ore to be separated comprises sulfide minerals and / or precious metals based on Cu, Mo, Fe, Au, Ag, or a combination thereof.

19. A froth flotation separation composition comprising an aqueous medium, a frother, a collector formulation, and optionally a pH modifier comprising a hydroxyl group and lithium, sodium, potassium, calcium, or a combination thereof, but comprising substantially no sodium cyanide nor potassium cyanide, the collector formulation consisting essentially of: a polysulfide having one or more -Sn- moieties in which n is at least 4 and comprising from 9 wt% to 45 wt% sulfur content, based on a total weight of the polysulfide, wherein the polysulfide is comprised from a reaction product of elemental sulfur and one or more unsaturated hydrocarbon and / or oxygen heteroatom-containing hydrocarbon compounds, said reactant hydrocarbon compounds comprising limonene, dicyclopentadiene, soybean oil, propylene tetramer, butylene trimer, Cl 1 -Cl 8 unsaturated fatty acids and / or C1-C4 alkyl esters, and combinations thereof; optionally an additional collector comprising n-dodecyl mercaptan, tert-dodecyl mercaptan, isopropyl ethylthionocarbamate, potassium amyl xanthate, sodium dicresyl dithiophosphate, or a combination thereof; optionally a hydrocarbon diluent comprising kerosene; optionally a dispersant comprising 2-ethylhexanol, a polypropylene glycol), or a combination thereof; and optionally a depressant comprising dextrin.

20. Use of the froth flotation separation composition according to claim 19 in a froth flotation separation method to separate minerals in an ore comprising sulfide minerals and / or precious metals based on Cu, Mo, Fe, Au, Ag, or a combination thereof, to form a mineral concentrate.

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