OA16574A - Separation of copper minerals from pyrite using air-metabisulfite treatment. - Google Patents

Abstract

Embodiments of the present invention are directed to flotation of sulfidic materials following aerating by an oxidizing gas and contacting by a sulfoxy reagent.

Description

The présent application claims the benefits of U.S. Provisional Application Serial No. 61/266,770, filed December 4, 2009, entitled Séparation of Copper Minerais from Pyrite in Buffered Water Solutions Using Air-Metabisulfite Treatment, which is incorporated herein by this reference in its entirety.

FIELD

The invention relates generally to métal recovery and particularly to recovery of copper, molybdenum and/or gold minerais by flotation in waters with a range of buffering capacities and/or salinities.

BACKGROUND

The employment of flotation to upgrade valuable minerais from pyrite and other gangue minerais is generally performed at an alkaline pH. Alkalinity is controlled by the addition of lime or other alkaline compounds. Lime is normally employed as it is a relatively inexpensive reagent; however, large amounts of lime and other reagents are required when the water available to the flotation circuit possesses a high buffering capacity. In other words, a large amount of lime is necessary to alter and maintain the pH at the optimal operating conditions. The addition of lime can also depress the flotation of minerais such as chalcopyrite, sphalerite, molybdenite, pyrite, pyrrhotite, and gold and other precious metals via the déposition of calcium on the métal surface.

Commonly, in sulfide flotation, the effectiveness of flotation agents is controlled by the level of alkalinity or acidity in the flotation feed or pulp pH regulators such as lime, soda ash and, to a lesser extent, caustic soda, are often employed as the pH controlling agents. Lime is the most commonly used agent because of its cost, availability and ability to maintain pH values of pH 10.5 and above. Adjustment of the pH of the pulp to pH 11.0 is required to depress the gangue sulfide minerais of iron, such as pyrite and pyrrhotite. The costs associated with adding lime can be significant and the effectiveness of lime as a depressant has been shown herein to be reduced in waters containing high levels of dissolved salts or are highly buffered.

Other sulfide depressants hâve been employed to depress pyrite, such as cyanide or sodium hydrosulfîde, in conjunction with pH modification. They cannot be used over a wide pH range and require high pH values, so that high lime consumption remains an issue. In addition these depressants may not be sufficiently sélective at économie dosages.

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The use of sulfoxy compounds to improve the recovery of sulfide minerais was described as far back as US 2,154,092 to Hunt. This patent describes a process to treat ores containing carbonaceous or graphitic substances associated with gangue components. These carbonaceous substances may either remain with the valuable ore minerai during flotation and reduce the grade or coat the valuable minerais, thereby reducing their recovery by flotation. To prevent this, sulfur dioxide or any other reducing gas, is added to the pulp, without mixing it with air, to inliibit the flotation of the deleterious gangue and carbon coated minerais.

When the sulfur dioxide gas is added, Hunt states that the resulting pH of the pulp water is usually on the acid side (<pH 7). In some cases, depending on the natural alkalinity of both the 10 ore and the milling water, the pulp may remain alkaline. The process can be carried out when the pulp is either acid or alkaline.

Hunt teaches that the reducing gas may also be intemally generated in the ore pulp itself by the action of one or more suitable chemicals. For example, when sulfuric acid and an alkaline (base) or alkaline earth sulfite, bisulfite, or thiosulfate are added to an ore pulp, sulfur dioxide 15 will be one of the products resulting from the interaction.

A number of other patents hâve employed sulfoxy compounds in sulfide flotation circuits.

US Patent 5,171,428 to Beattie, et al., describes a process to separate arsenopyrite from a mixture with pyrite by contacting the mixture with a sulfitic agent providing HSO3· ion, The 20 process is performed at an elevated température and a pH below about pH 8 for a period sufficient to impart a sélective dépréssion of arsenopyrite.

US Patents 6,032,805, and 6,092,666 to Clark, et al., disclose a method for reducing the consumption of alkaline pH modifiers by using a sulfoxy radical-containing reagent. Prior to or simultaneously with the introduction of the sulfoxy radical-containing reagent, a non-oxidizing 25 gas (such as an inert or reducing gas) is added in a quantity sufficient to achieve a chemical environment conducive to the flotation séparation of minerais. Prior to collecter and frother addition but after contact with the non-oxidizing gas, the slurry, only when necessary, is aerated by an oxidizing gas to a particular dissolved oxygen concentration or electrochemical potential suitable for flotation.

US Patent 6,041,941 to Newell, et al., présents a similar process to Clark, et al., with the aim of reducing reagent consumption and minerai scale formation in flotation circuits. In the process of Clark, et al., the non-oxidizing gas is added to prevent the oxidation of the sulfoxy radical. The non-oxidizing gas is introduced during the reagent conditioning and flotation stages.

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At these stages, the dissolved oxygen in the slurry is most likely to dégradé the sulfoxy compounds and resuit in scale formation.

There is a need for a process that can separate valuable metal-containing sulfide minerais from other sulfide minerais, particularly sulfidic gangue minerais, while controliing levels of reagent consumption in waters with a significant range of buffering capacities and/or salinities, without the addition of lime or other pH modifiers.

SUMMARY

These and other needs are addressed by the various embodiments and configurations of the présent invention. The invention is directed generally to sulfoxy reagent-assisted flotation séparation of valuable métal sulfide minerais from other sulfides, particularly pyrite, marcasite, pyrrhotite, arsenopyrite, and other gangue minerais.

In an embodiment, a sulfoxy reagent, preferably an ammonium, hydrogen, alkali métal, and/or alkaline earth métal metabisulfite, is added to an aerated, slurried valuable metalcontaining sulfidic feed material prior to flotation. The process is particularly applicable to the flotation séparation of copper sulfides, such as chalcocite (Cu₂S), bomite (CusFeS;}), chalcopyrite (CuFeSi), covellite (CuS), tetrahedrite (Cui₂Sb4S]3), tennantite (CU12AS4S13), and enargite (CU3ASS4) and/or molybdenum sulfide (e.g., as molybdenite (M0S2)), on the one hand from pyrite (FeS₂), marcasite (FeS₂), pyrrhotite (Fej._sS), arsenopyrite (FeAsS) on the other. The sulfoxy reagent acts as a depressant of the gangue sulfide minerais. In this manner, a highly sélective flotation séparation of different sulfide minerais can be realized.

Unlike conventional flotation processes which strip molecular oxygen from the slurry prior to sulfoxy reagent addition, the sulfoxy reagent is added to an aerated valuable metalcontaining feed material. The aération step is operated to the extent that a thin layer of surface oxidation is formed on copper sulfide minerais to promote the adsorption of the collecter and therefore flotation of the copper minerais. To promote the formation of this layer, the slurried valuable metal-containing feed material is preferably not contacted with an extemally generated non-oxidizing gas to lower the dissolved molecular oxygen content, prior to the floating step.

In some embodiments, tire sulfoxy reagent is introduced after aération and before pulp conditioning with the collecter and frother.

In some embodiments, the sulfoxy reagent is introduced not only after aération but additionally in the primary and/or secondary grinding circuit. While not wishing to be bound by any theory, this enables the sulfoxy reagent to contact freshly exposed and unoxidized minerai sulfide surfaces, thereby enhancing the effectiveness of the reagent.

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In some embodiments, the flotation process is performed at natural pH and in the substantial absence of pH modification. Stated another way, no acid or base is added to adjust the pH of the slurried feed material at any stage in the comminution and flotation circuits unless pH modification is performed for économie reasons, such as to reduce sulfoxy reagent dosage, reduce any corrosion effect, and/or to avoid a lower pH situation when high sulfoxy reagent dosage is needed. pH modification, however, must be carefully controlled to avoid adversely impacting valuable métal recovery or concentrate grade.

The process can use, in pulp formation, any quality of water, whether fresh, brackish, or sait water and regardless of the degree of buffering.

The combination of the aération stage followed by a sulfoxy reagent addition stage, and in the absence of pH adjustment, can resuit in increased copper sulfide minerai flotation rate and recovery and improved copper sulfide minerai concentrate grade. Although the dissolved molecular oxygen level produced by aération may, in certain situations, increase sulfoxy reagent consumption, the substantial improvement in kinetics and élimination of lime reagent requirements can more than offset any increase in sulfoxy reagent costs. This process is particularly useful when the water available to form the flotation pulp eontains significant buffering capacity and is effective over a broad pulp pH range. In fact, the process can be more cost effective in terms of recovery and reagent consumption than conventional processes using lime addition and cyanide. The process has demonstrated superior performance when used in water containing negligible to significant buffering capacity or salinity. Accordingly, the process is particularly useful for concentrator operations whose only available source of water is sea water or brackish ground water.

These and other advantages will be apparent from the disclosure of the invention(s) contained herein.

The term a or an entity refers to one or more of that entity. As such, the terms a (or an), one or more and at least one can be used interchangeably herein. It is also to be noted that the terms “comprising”, “including”, and “having” can be used interchangeably.

The phrases at least one, one or more, and and/or are open-ended expressions that are both conjunctive and disjunctive in operation. For example, each of the expressions at least one of A, B and C, at least one of A, B, or C, one or more of A, B, and C, one or more of A, B, or C and A, B, and/or C means A alone, B alone, C alone, A and B together, A and C together, B and C together, or A, B and C together. When each one of A, B, and C in the above expressions refers to an element, such as X, Y, and Z, or class of éléments, such as XI-Xn, YlYm, and Zl-Zo, the phrase is intended to refer to a single element selected from X, Y, and Z, a

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* combination of éléments selected from the same class (e.g., XI and X2) as well as a combination of éléments selected from two or more classes (e.g., Y1 and Zo).

The term “brackish water” refers to water having more salinity than fresh water but not as much as sait water. Typically, brackish water has a salinity ranging from about 0.1 parts per thousand (0.01%) to about 25 parts per thousand (2.5%).

The term “buffering capacity” refers to the degree to which a solution can resist the alteration of its pH when extemal pH modifiers are added.

The term “dissolve” and variations thereof refer to is the process by which a solid or liquid enters its aqueous phase (solution).

The term “metabisulfite” refers to the oxyanion of sulfur S2O52- or any sait containing this ion. Metabisulfïte usually is in the form of a métal and the bisulfite anion (S2O5), usually in the form of an alkali or alkaline earth métal metabisulfïte.

The term “minerai” and variations thereof refer to any naturally formed chemical substance having a definite chemical composition and characteristic crystal structure.

The term “natural pH” refers to the pH of a solution in the substantial absence of intentional pH modification. Intentional pH modification occurs when an acid or base is added to a solution for the purpose of adjusting the pH. An example of unintentional pH modification is when pH is adjusted by aération, pulp conditioning with a dotation reagent (such as a collecter, frother, activator, depressant, dispersant, and the like), or sulfoxy reagent addition.

The term “precious métal” refers generally to gold and silver.

The term “solution derived therefrom” refers to a solution having at least one common component with tire source solution from which the solution is derived, directly or indirectly. For example, a solution having a leaching agent, contaminant, or valuable métal found in the source solution is deemed to be derived therefrom. Thus, a raffinate or barren solution is deemed to be a solution derived from a prégnant leach solution. Likewise, a loaded extractant or electrolyte, which contains the valuable métal, or strip solution are deemed to be derived, directly or indirectly, from the prégnant leach solution. Likewise, a slurried concentrate or tailings is deemed to be derived from the feed material to the flotation stage.

The term “sulfide minerai” refers to a minerai containing métal as the cation and sulfide (S2-) as the major anion.

The term “sulfoxy reagent” refers to a composition containing an ingrédient in which oxygen is directly bonded to S, such as S=O, SO3X, SO4, etc., or which acts as a source for the sulfoxy radical.

The term “sait water” refers to water, typically océan or seawater, having a salinity of t

* about 25 parts per thousand (2.5%) or more, more typically of about 30 parts per thousand (3.0%) or more, and even more typically of about 35 parts per thousand (3,5%) or more. Sait water typically has a total dissolved solids of about 10,000 mg/L or more, even more preferably of about 20,000 mg/L or more, and even more preferably of about 25,000 mg/L or more. Although seawater contains more than 70 éléments, most seawater salts are ions of six major éléments: chloride, sodium, sulfate, magnésium, calcium, and potassium.

The term “salinity” refers to the dissolved sait content of a body of water. It describes the levels of different salts such as sodium chloride, magnésium and calcium sulfates, and bicarbonates.

The term “sulfite” are compounds that contain the sulfite ion SO (additive IUP AC name: trioxidosulfate(2- )). The sulfite ion is the conjugate base of sulfurous acid.

The term “valuable métal” refers to silver, gold, a nonferrous base métal (nickel, lead, copper, and zinc), cobalt, molybdenum and mixtures thereof, with copper being a common métal in the sulfide matrix.

The preceding is a simplified summary of the invention to provide an understanding of some aspects of the invention. This summary is neither an extensive nor exhaustive overview of the invention and its various embodiments. It is intended neither to identify key or critical éléments of the invention nor to delineate the scope of the invention but to présent selected concepts of the invention in a simplified form as an introduction to the more detailed description presented below. As will be appreciated, other embodiments of the invention are possible utilizing, alone or in combination, one or inore of the features set forth above or described in detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are incorporated into and form a part of the spécification to illustrate several examples of the présent invention(s). These drawings, together with the description, explain the principles of the invention(s). The drawings simply illustrate preferred and alternative examples of how the invention(s) can be made and used and are not to be construed as limiting the invention(s) to only the illustrated and described examples. Further features and advantages will become apparent from the foliowing, more detailed, description of the various embodiments of the invention(s), as illustrated by the drawings referenced below.

Fig. 1 is a flowchart of a process according to an embodiment;

Figs. 2A-B are a flowchart of a process according to an embodiment;

Fig. 3 is a flowchart of a process according to an embodiment;

Fig. 4 is a flowchart of a process according to an embodiment;

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Fig. 5 is a copper recovery curve for various flotation reagent schemes in tap water and plots copper grade (%) against copper recovery (%);

Fig. 6 is a copper recovery curve for various flotation reagent schemes in sait water and plots copper grade (%) against copper recovery (%);

Fig. 7 is a copper recovery curve for various flotation reagent schemes in tap water and plots copper grade (%) against copper recovery (%);

Fig. 8 is a copper recovery curve for various flotation reagent schemes in sait water and plots copper grade (%) against copper recovery (%);

Fig. 9 is a copper recovery curve in sait water and tap water with MBS addition, with and without aération, and plots copper grade (%) against copper recovery (%); and

Fig. 10 is a copper recovery curve in brackish site water and tap water with MBS addition, with and without aération, and plots copper grade (%) against copper recovery.

DETAILED DESCRIPTION

The process described herein employs the addition of a sulfoxy reagent, preferably a metabisulfite, to one or more points in a flotation circuit. In one process configuration, the addition of the sulfoxy reagent is preceded by a period of, typically intense, aération, in which an oxidizing atmosphère and dissolved molecular oxygen is actively promoted, rather than prevented or inhibited. The combination of aération with sulfoxy reagent addition, without adjustment of the pH of the resulting pulp with a base, such as lime, caustic soda, or soda ash, or an acid, such as sulfuric acid, and in the absence of sulfide depressants, such as cyanide or hydrosulfide, can show a marked improvement over the addition of a sulfoxy reagent without, or in the absence of, the aération step and can be more cost effective in terms of recovery and reagent consumption than conventional processes that employ base and/or sulfide depressant addition. In addition, the process can hâve superior performance when used in water containing negligible to a significant amount of salinity. This process can be particularly useful for concentrator operations whose only available source of water is sea water or brackish ground water. In other embodiments, the sulfoxy reagent is introduced not only after aération but additionally in a grinding circuit, particularly the secondary grinding circuit..

Referring to Fig. 1, a valuable metal-containing feed material 100 can be any suitable copper- and/or molybdenum containing material, particularly mined ore, tailings, concentrate, or other residue of a métal recovery process. The feed material 100 includes not only one or more copper and/or molybdenum sulfide minerais but also one or more other sulfide minerais (particularly sulfidic gangue minerais) to be separated from the valuable métal sulfide mineral(s)). Typically, the feed material 100 is polymetallic, with some or ail of the metals £

t being present as a sulfîde, A common feed material 100 includes copper in the form of one or more of chalcopyrite, chalcocite, bomite, covellite, tennantite, enargite, and tetrahedrite and/or molybdenum in the form of molybdenite as the valuable métal sulfîde minerai and an iron sulfîde minerai that is one or more of pyrite, marcasite, arsenopyrite, and pyrrhotite, as a sulfidic gangue minerai. Gold or silver is typically present. In many applications, iron sulfîde is the primary (e.g., more than 50% of the) sulfidic gangue minerai in the feed material 100.

In step 104, the material 100 is slurried and comminuted in an open or closed milling circuit. The comminuted feed material 108 is forwarded to an aération step 112 prior to the sulfoxy reagent addition step 114.

The water used in forming the slurry of the material 100 can be fresh water, brackish groundwater, saltwater, or any mixture thereof. The process is surprisingly effective in floating valuable métal sulfîde minerais whether or not the water is saline and contains dissolved solids or is fresh water. In one process configuration, for example, the water has a salinity of about 0.1 parts per thousand (0.01%) or more.

The optimum libération size of the material 100 dépends on ore type, an understanding of the ore libération and solution chemistry of the ore, and power and media costs.

The comminuted feed material 108 is in the form of a slurry, preferably having a feed pulp density ranging from about 20 to about 45 wt.%.

The comminuted feed material 108 is subjected to aération in step 112 in a suitable vessel to form an aerated feed material 132. Aération is typically performed by sparging, under agitation, an oxidizing gas, preferably a molecular oxygen-containing gas (such as air, substantially pure molecular oxygen, and molecular oxygen-enriched air) through the feed material 108. The oxidizing gas preferably includes at least about 20 vol. % molecular oxygen. Aération is performed for a time sufficient to allow a thin layer of surface oxidation to form on the surface of the copper and/or molybdenum sulfîde minerais 108. The résidence time requîred to produce the desired oxidized film ranges preferably from about 15 to about 120 minutes and more preferably from about 30 to about 60 minutes. In most applications, the pH is not adjusted during aération or any steps subséquent to aération.

While not wishing to be bound by any theory, the thin layer of surface oxidation on the copper and/or molybdenum sulfîde minerais allows better collecter adsorption by the minerai. This is surprising to one of ordinary skill in the art, who would believe that aération leads to oxidation of the copper and molybdenum sulfîde minerais causing reduced floatability and reduced stability of the sulfoxy compound.

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In step 114, the sulfoxy reagent 118 is added to the aerated feed material 132 to form a treated feed material 122. Sulfoxy reagent 118 can be added in any suitable manner. Unlike conventional processes, the sulfoxy reagent 118 is added while the aerated feed material 132 is oxygenated. In other words, dissolved molecular oxygen is not removed from the comminuted feed material prior to sulfoxy reagent 118 addition. The dissolved molecular oxygen level in the aerated feed material 132 during conditioning is preferably at least about 3 ppm, more preferably at least about 5 ppm, and even more preferably at least about 10 ppm.

The sulfoxy reagent 118 can be any sulfoxy compound, such as an ammonium, hydrogen, alkali métal, or alkaline earth métal sulfite, bisulfite, metabisulfite, sulfide, polysulfide, thiosulfate, polythionate, or bisulfide, sulfur dioxide, and mixtures and dérivatives thereof. The preferred sulfoxy reagent 118 is one or more of an ammonium, hydrogen, alkali métal, or alkaline earth métal sulfite, bisulfite, or metabisulfite, and/or sulfur dioxide, with an ammonium, hydrogen, alkali métal, or alkaline earth métal metabisulfite being even more preferred. While not wishing to be bound by any theory, the sulfoxy reagent 118 is believed to act as a depressant of other sulfide minerais (e.g., iron sulfide gangue minerais, particularly pyrite). As will be appreciated by one of ordinary skill in the art, sulfite ion can be added or formed in situ by a suitable chemical reaction between sulfite ion precursors.

There are a number of different process configurations for sulfoxy reagent 118 addition. In one process configuration, a portion of the sulfoxy reagent 118 is added in one stage, optionally during grinding, with additional amounts being added after aération and before each of the cleaning, recleaning or scavenging flotation stages. In another process configuration, the majority of the sulfoxy reagent 118 is added in one or more stages after aération, with additional smaller amounts being optionally added before each of the cleaning, recleaning or scavenging flotation stages. In another process configuration, no sulfoxy reagent 118 is added during any grinding stage but only after aération. The typical cumulative sulfoxy reagent 118 addition rate, for ail addition points, is at least about 50 g/t, more typically at least about 100 g/t, more typically more than 200 g/t, and even more typically from more than 200 g/t to about 1,000 g/t.

While not wishing to be bound by any theory, it is believed that the sulfoxy reagent and oxidizing gas act synergistically to enhance substantially séparation selectively and effectiveness, particularly in highly buffering and/or saline waters. While aération is believed to oxidize sulfide minerai surfaces, which increases floatability of the valuable métal sulfide minerai, the addition of sulfoxy reagent after aération is believed to control optimally the dépréssion of the other sulfide minerai to be removed as tailings. The increase in floatability, for example, of copper sulfide minerais with aération while depressing pyrite with the sulfoxy reagent can allow a much improved flotation selectivity than is possible in the absence of aération. This synergistic effect is best realized when aération and sulfoxy reagent addition occur sequentially, with aération preceding sulfoxy reagent addition.

In step 116, the treated feed material 122 is conditioned to form an aerated and conditioned feed material 134, Conditioning is performed in a suitable vessel, or pulp conditioning tank, prior to flotation. In flotation, the amount of agitation and conséquent dispersion during conditioning are closely associated with the time required for physical and chemical reactions to take place.

A number of reagents can be added during conditioning, including a collecter 120, a frother 124, and other reagents 128. Any suitable collecter 120 and frother 124 may be employed. Other reagents 128 include activators, depressants (such as a carbon depressant to depress the flotation of carbonaceous and/or graphitic material), clay dispersants, modifiers, lime (in limited situations as a low cost dispersant or viscosity modifier as examples), and reagents to control electro potential (Eh) and/or pH. Depending on the type of agitation during conditioning, the level of oxygénation may increase. For a downflow agitator, additional molecular oxygen will likely be entrained in the slurry. Conditioning typically occurs for a period between about 0.5 to about 60 minutes and even more typically between about 2 to about 30 minutes.

The aerated and conditioned feed material 134 is floated in step 136, preferably in the presence of sparged air, to form a concentrate fraction 144 commonly containing about 25% or more, more commonly about 40% or more, and even more commonly more than about 50% of the valuable métal sulfide minerais and a tailings fraction 140 commonly containing about 25% or more, more commonly about 40% or more, and even more commonly more than about 50% of the sulfide mineral(s) to be removed as tailings. In the flotation circuit, the aerated and conditioned feed material 134 is floated in a bank, or sériés, of flotation machines. The flotation machines can be aerated flotation cells.

Flotation may include one or more stages, depending on the application. The number and configuration of roughing, scavenging, and cleaning stages are determined based on criteria known to those skilled in the art.

The sélection of the collecter 120, frother 124, and other reagents 128 for a spécifie feed material as well as the pulp density, addition rates of the reagents, order of reagent addition, rate of air addition during flotation, Eh, and other flotation conditions and parameters are also well known to those of ordinary skill in the art.

In one process configuration, the comminution step 104, aération step 112, conditioning step 116, and flotation step 136 are performed in the substantial or complété absence of pH

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adjustment by an acid or base (e.g., in the absence of acid or base (e.g., lime, soda ash, and/or caustîc soda) addition). In other words, the steps are performed at natural pH., which, for many ores and makeup water, is an alkaline pH of no more than about pH 11, more typically a pH of less than pH 8.5, more typically a pH of no more than about pH 8, and even more typically a pH ranging from about pH 3 to about pH 8. The Eh will typically be greater than about 5 mV and less than about 155 mV and more typically range from about 10 to about 120 mV.

In one process configuration, the comminution step 104, aération step 112, conditioning step 116, and flotation step 136 are performed in the substantial or complété absence of dissolved molecular oxygen réduction by sparging the slurried feed material with a nonoxidizing gas. The non-oxidizing gas has little, if any, oxidant content and is primarily, if not entirely, an inert gas (e.g., nitrogen and argon), a reducing gas (e.g., a reducing gas other than sulfur dioxide such as carbon dioxide, carbon monoxide, methane, ethane, and/or propane), or a mixture thereof. In one process configuration, the added sulfoxy reagent 118 is substantially free of sulfur dioxide gas. By eliminating sparging by the non-oxidizing gas, a relatively high level of dissolved molecular oxygen can be maintained in the slurry before and after aération.

Another process configuration will now be discussed with reference to Figs. 2A-B. In this example, the valuable métal sulfide minerai is a copper sulfide and the other sulfide minerai (or sulfidic gangue minerai) is one or more of pyrite, marcasite, pyrrhotite, and arsenopyrite.

The valuable metal-containing feed material 100 is comminuted in step 104 to form a comminuted feed material 108.

The comminuted feed material 108 is conditioned in step 116 to form a conditioned feed material 132. The reagents added during conditioning are the collecter 120, frother 124, and other reagents 128. No sulfoxy reagent 118 is added.

The conditioned feed material 132 is subjected to rougher flotation in step 200 to form rougher tailings 204 and rougher concentrate 208. While most of the valuable métal sulfide minerais remain in the rougher concentrate 208, the rougher tailings 204 contain a signifïcant portion of the sulfide gangue minerais. As can be seen from Fig. 2A, no sulfoxy reagent 118 has been added prior to rougher flotation.

In step 228, the rougher and scavenger concentrate 208 and 220, respectively, are combined, pulp density adjusted, and recomminuted, in a closed or open comminution circuit, to form a recomminuted concentrate 232. As will be appreciated, the floated iron sulfide minerais in the concentrate fraction 208 are more difficult to separate and require further comminution for effective libération to be realized. .

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Sulfoxy reagent 118 may optionally be added during secondary comminution and after aération. Addition of the sulfoxy reagent in the mill can allow immédiate adsorption of the sulfoxy radical on fresh and unoxidized sulfide minerai surfaces. In one configuration, more sulfoxy reagent 118 is added before cleaner flotatîon than at any other point during the process.

In step 212, the rougher tailings 204 are further conditioned by the addition of collecter 120, and, in step 216, the conditioned rougher tailings are subjected to scavenger flotation 216 te produce a scavenger concentrate 220 and scavenger tailings 224. Slower floating copper sulfide minerais are floated during scavenger flotation. The scavenger concentrate 220 is combined with the rougher concentrate 208 and subjected to secondary comminution.

Following secondary comminution step 228, the recomminuted concentrate 232 is subjected, in step 112, to aération to form an aerated concentrate 236.

In optional step 114, sulfoxy reagent 118 is added to form a treated rougher concentrate 238.

In step 116, the aerated or treated rougher concentrate 236 (as appropriate) is conditioned to form a conditioned concentrate 240. Reagents added during conditioning are the collecter 120, frother 124, and other reagents 128. Typically, aération, sulfoxy reagent addition, and conditioning occur in different vessels, and the dissolved molecular oxygen after aération is not, prior to sulfoxy reagent addition, reduced by introduction of a non-oxidizing gas.

In step 248, the conditioned concentrate 240 is subjected to cleaner flotation to form cleaner tailings 252 and cleaner concentrate 250. While most of the valuable métal sulfide minerais in the conditioned concentrate 240 remain in the cleaner concentrate 250, the cleaner tailings 252 contain a portion of the valuable sulfide minerais in the conditioned concentrate 240. The cleaner tailings contain a significant amount of the gangue sulfide minerais.

In optional step 114, sulfoxy reagent 118 is added to the cleaner tailings to form a treated cleaner tailings 262.

In step 256, the cleaner tailings 252 or treated cleaner tailings 262 (as the case may be) are conditioned by addition of collecter 120 to form conditioned cleaner tailings 260. The conditioned cleaner tailings 260 are subjected to cleaner scavenger flotation in step 264 to form cleaner scavenger tailings 268 and concentrate 272. While most of the valuable métal sulfide minerais in the cleaner tailings 252 remain in the cleaner scavenger concentrate 272, the cleaner scavenger tailings 268 contain a significant portion of the sulfide gangue minerais in the cleaner tailings 252. The cleaner scavenger concentrate 272 is retumed to the secondary comminution step 228.

Retuming to the cleaner concentrate 250, sulfoxy reagent 118 is, in step 114, optionally

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added to the cleaner concentrate to form a treated cleaner concentrate 252.

The cleaner concentrate 250 or treated cleaner concentrate 252 (as appropriate) is conditioned in step 274 to form a conditioned cleaner concentrate 276. During conditioning, collecter 120 is added.

The conditioned cleaner concentrate 276, in step 278, is subjected to first recleaner flotation to form first recleaner tailings 282 and first recleaner concentrate 280. The first recleaner tailings 282 are returned to the secondary comminution step 228.

In optional step 114, sulfoxy reagent 118 is added to the first recleaner concentrate 280 to form a treated recleaner concentrate 281.

The first recleaner concentrate 280 or treated recleaner concentrate 281 (as the case may be) is conditioned, in step 284, to form a conditioned first recleaner concentrate 286. During conditioning, the first recleaner concentrate 280 collecter 120 is added.

In step 288, the conditioned first recleaner concentrate 286 is subjected to second recleaner flotation 288 to form second recleaner tailings 290, which includes preferably at least most and more preferably about 70% or more of the sulfidic gangue minerais in the valuable metal-containing feed material 100, and second recleaner concentrate 292, which includes preferably at least most and more preferably about 70% or more of the valuable métal sulfide minerais in the valuable metal-containing feed material 100.

In the above process, cleaner flotation, cleaner scavenger, and first and second recleaner flotation steps 244, 264, 278, and 288, respectively, are performed at natural pH and ambient température.

In the above process, it may be désirable to perform an additional aération step preceding one or more of the sulfoxy reagent addition steps performed downstream of rougher flotation. Whether or not an additional aération step is performed dépends on the oxidation potential ofthe slurry before further sulfoxy reagent and collecter addition. Prior conditioning, aerating, and floating steps will introduce additional dissolved molecular oxygen into the various slurry streams.

As will be appreciated, other process configurations may be employed depending on the feed material type and mineralogy.

EXPERIMENTAL

The following examples are provided to illustrate certain embodiments ofthe invention and are not to be construed as limitations on the invention, as set forth in the appended claims. Ail parts and percentages are by weight unless otherwise specified.

Example 1 - Conventional Flotation Methods

This example demonstrates the effect that the composition of water employed in the flotation pulp has on the recovery of copper, when various reagents are used to depress pyrite and concentrate copper. As shown in Table 1, the sait water employed has considerably higher total dissolved solids content and conductivity than the tap water.

Table 1: Composition of Tap and Highly Buffered Site Water

Parameter	Units	Tap Water	Sait Water
pH	pH	7.81	8.48
Conductivity	pS/cm	0.96	5360
TDS	mg/L	405	40225
Sodium	mg/L	191	12060
Potassium	mg/L	9.3	414
Calcium	mg/L	332	426
Magnésium	mg/L	10.4	1297
Iron	mg/L	0.17	<0.10
Chloride	mg/L	199	20738
Bicarbonate	mg/L	120	70
Sulfate	mg/L	NIL	2890

Fig. 3 is a simplified flow diagram of the kinetics tests conducted in this example. The flow diagram includes comminuted feed material conditioning 300 to form a conditioned feed material 304, rougher flotation 308 ofthe conditioned feed material 304 (using five flotation machines) to form rougher tailings 312 and rougher concentrate 316, secondary comminution 10 320 of the rougher concentrate 316 to form recomminuted rougher tailings 324, first cleaner flotation 328 of the recomminuted rougher tailings 324 to form a first cleaner concentrate 332 and first cleaner tailings 336, second cleaner flotation 344 of the first cleaner concentrate 332 to form second cleaner concentrâtes 1,2 348 and second cleaner tailings 352, and cleaner scavenger flotation 340 of the first cleaner tailings 336 to form a cleaner scavenger concentrate 356 and 15 cleaner scavenger tailings 360.

The five rougher stages for the kinetics tests described below were performed in a similar manner using two water sources: tap water, and water with a high degree of Total Dissolve Solids (TDS) (Sait Water). Ail tests were carried out on ore ground to Pgo 212 microns for the rougher stages and reground to P go 20 -25 microns for the cleaner scavenger. Other than reagent 20 addition, the tests were carried out using the same conditions.

The effect of different reagent additions on sulfide dépréssion and the associated copper grade/recovery was investigated. The reagents employed were none, lime, lime and sodium cyanide, and lime cyanide and Potassium Amyl Xanthate (“PAX”).

The composition of the feed (ore) material employed in ail the tests is shown in Table 2. 25 The initial feed pulp density was 34%. The experimental conditions are shown below in Table 3.

Table 2: Feed ore employed in flotation tests with tap and sait water

Parameter	Unit	Assay
Copper	%	0.478
Iron	%	3.66
Gold	g/t	0.28
Total Sulfur	%	4.34
Sulfide Sulfur	%	1,84

Table 3: Reagent addition and operating conditions for flotation tests performed with tap and sait water

Tap Water	ra £ c o E p	| 30.5 |	| 30.5 |	| 30.5 [	| 30.5 |
| Reagent Addition	Φ E? _i —		LO O) CM	LD O CM	o cxi CN
MIBC . drops	(D v	r-	r-	O
z _ O ü < o z “		o	O CM	20
O				46
o en ü X S Ξ	rco	rco	1 37
M· o s <	□>	σ>	CT>	T CM
> E JZ LU	cleaner	T CM	T	1 a- 1	CCM 1
rougher	co CD	CD T- 5“	rCN	| 105
T	cleaner	I 7.2 I	CM O	| ZOL |	10.2
Q.	rougher	CO t<	I 7.35 I	r<	7.5
	Test Description	|Baseline |	| Baseline with lime |	[Baseline with lime and cyanide 1	(Baseline with lime, cyanide and PAX

	h» ra 0 E	o C i’Ë 4-» ^3	| 30.5 |	| 30.5 |	| 30.5 |	| 30.5 |
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Figures 5 and 6 above show the grade recovery curves for the four reagent schemes for tap water and sait water, respectively. For ail of the reagent schemes tested, the grade recovery curves for low TDS tap water were better than than those achieved with sait water. Tap water with Lime Cyanide and PAX has the best grade recovery curve. Compared to tap water, conventional techniques employed for pyrite dépréssion do not perform as well in sait water.

Example 2 - Aeration/Sulfoxy Reagent Methods

Additional tests were conducted using a similar flotation circuit as employed in example 1 with the exception of the addition of 300g/t before the first stage of cleaner flotation and an additional 300g/t metabisulfite (MBS) (the sulfoxy reagent) during the secondary grînd. In other words and as shown in Table 4 below, a total of 600g/t MBS has been added in the flotation circuit.

The flotation circuit is shown in the flow chart of Fig. 4. The flow chart includes conditioning 400 of the comminuted feed material 108 to form conditioned feed material 404, rougher flotation 408 (using five flotation machines or stages) to form rougher concentrate and tailings fractions 412 and 416, respectively, secondary comminution 420 of the rougher concentrate 412, in the presence of sulfoxy reagent 118, to form a recomminuted rougher concentrate 412, aération 112 of the recomminuted rougher concentrate 412 (for 0 (which means no aération was performed) or 30 minutes) to form aerated recomminuted rougher concentrate 428, sulfoxy reagent 118 addition prior to cleaner flotation 432, and cleaner flotation 432 of the aerated recomminuted rougher concentrate 428 to form cleaner concentrate 1-6 and cleaner tailings 436 and 440, respectively.

Again, the same two types of water where employed: tap water and sait water with a high degree of TDS (Sait Water). Ail tests were carried out on feed (ore) material ground to P go 212 microns for the five rougher stages and reground to Peo 20-25 microns for the cleaner scavenger. Other than reagent addition, the tests were carried out using the same conditions. The initial feed pulp density was about 34%, and the feed (ore) material was the same as that employed in example 1. The experimental conditions are shown below in Table 4. The tests were carried out with and without a 30-minute aération step after the secondary comminution step, or secondary grind, and prior to the cleaning flotation circuit. The effect of the aération before MBS addition on sulfide dépréssion and copper grade/recovery was investigated. For reference, the grade recovery curve with lime cyanide and PAX is shown.

Table 4: Reagent addition and operating conditions for flotation tests performed with tap and sait water

Site Water

Test Description	pH	EhmV	i ReagentAddition	Hoat time W
rougher	cteaner	rougher	cleaner	U»|'	MX950 ' W	MBS W	MIBC drops	Lime Λ
MBS with aeialion	7.4	5.6	115	85	9	37	600	13	0	30.5
MBS with no aération	7.4	4.8	91	95	9	37	600	12	0	30.5

Sait Water

Test Description	PH	EhmV	ReagentAddition	Hôàt time, imin)
rougher,	cleaner	rougher	cleaner	A3B94 Π	m w	MBS	MIBC drops,’	Lime w
MBS with aération	7.5	5.2	94	9	37	600	12	0	30.5
MBS with no aération	7.5	4.9	103	90	9	37	600	14	0	31.5

As can be observed from the grade recovery curves of Figs. 7-8, the use of MBS improves the copper grade recovery curves in both water types. The effect is most pronounced in sait water. However, it is not until aération is employed that the grade recovery achieved in sait water begins to approximate that observed in the tap water. A graph more clearly comparing the copper grade recovery, with and without aération, is shown in Fig. 9. In sait water, MBS addition improves the copper recovery from 50% to 75% at the same copper grade of 32%.

Example 3- Aeration/Sulfoxy Reagent Methods

Additional tests were conducted using the same flotation circuit of Fig. 4 as employed in example 2, with the exception that brackish site water was employed. Analysis ofthe site water is shown in Table 5. The tests were carried out, with and without, a 30-minute aération step after the secondary grind and prior to the cleaning 20 flotation circuit. The effect of the aération, after MBS addition, on sulfide dépréssion and copper grade/recovery was investigated. For reference the grade recovery curve with tap water is shown in Figs. 10.

Table 5: Composition of Tap and Highly Buffered Site Water

Parameter	Units	Site Water
pH	pH	7.02
Conductivity	pS/cm	10.38
TDS	mg/L	7515
Sodium	mg/L	1940
Potassium	mg/L	11.2
Calcium	mg/L	620
Magnésium	mg/L	84.5
Iron	mg/L	<0.10
Chloride	mg/L	2535
Bicarbonate	mg/L	30
Sulfate	mg/L	1198

Example 4 - Locked Cycle Testing

Locked cycle tests were performed using differing ore types and a saline and buffered site water to compare flotation performed using sulfoxy reagent addition with that performed using cyanide as a depressant in the absence of aération and sulfoxy reagent addition. The various ores were copper sulfide ores containing substantial levels of iron sulfïdes. Actual locked cycle tests using site water are generally deemed to provide more valuable information than open cleaner tests. A summary of the locked cycle tests is presented in Tables 6-7:

Table 6: Locked cycle test results for the drop weight samples using the cyanide as a depressant and site water

Comp No		ore	% of	Hea d grade Cu,%	Con c Grade Cu,%	Mas s Pull	Rec overy Cu.%
deposl t
1			5.0	0.59	28.3	1.9	91.7
2			2.0	0.42	28.2	1.08	72.2
3			5.0	0.61	32.9	1.51	80.9
4			3.0	0.51	31.3	1.41	66.1
5			3.0	0.69	30.5	1.88	83.6
6			4.0	0.43	33.3	1.14	88.5
7			6.0	0.36	25.4	1.1	78
8			5.0	0.67	29.8	2.01	89.5
9			7.0	0.60	34	1.59	89.9
10			9.0	0.61	32.2	1.7	90.1
11			4.0	0.56	29.8	1.66	87.5
12			11.0	0.51	32.9	1.37	88.8
13			5.0	0.56	26.7	1.64	81
14			1.0	0.64	31	1.73	84.5
15			8.0	0.52	28.7	1.42	78.5
16			4.0	0.53	30.7	1.49	87.1

| Weig		30.5
| htod average	0.55	9	1.53	85.7

Table 7: Locked cycle test results for the drop weight samples using the Aeration/Metabisulfïte Process and site water

orrip No	C		% of ore	Hea d grade Cu,%	Con c Grade Cu,%	Mas s Pull	Rec overy Cu,%
de poslt
1		5.0	0.6	33.7	1.66	93.6
2		2.0	0.44	33.6	1.2	92.1
3		5.0	0.63	36.6	1.66	92.2
4		3.0	0.51	34.4	1.38	93.3
5		3.0	0.7	34	1.98	93.6
6		4.0	0.44	34.7	1.09	91.3
7		6.0	0.41	29	1.32	92.6
8		5.0	0.75	37.6	1.09	87.6
9		7.0	0.60	37.4	1.49	91
0	1		9.0	0.57	33.3	1.65	90.4
1	1		4.0	0.6	34.7	1.58	91.7
2	1		11. 0	0.48	33.2	1,44	92.4
3	1		5.0	0.56	24. Θ	2.11	90.6
4	1		1.0	0.6	33.7	1.78	93.5
5	1		8.0	0.51	32	1.43	90.3
6	1	Weighted average	4.0	0.53 0.55	36.8 33. 55	1.3 1.5 0	90.1 91.4 2

Both Tables 6-7 show that flotation with aération followed by ammonium metabisulfite addition yielded signifîcantly better results than flotation using cyanide as an iron sulfide depressant. On average, copper recovery was about 6% higher with about a 3% higher copper concentrate grade for flotation performed with aération followed by ammonium metabisulfite addition.

A number of variations and modifications of the invention can be used. It would be possible to provide for some features of the invention without providing others.

For example, the sulfoxy reagent has different modes of operation depending on the mineralogies and slurry conditions (e.g., Eh and pH) involved. Sulfoxy reagent, for 15 example, can act as a depressant and/or activator for the same sulfide minerai under differing slurry conditions or as a depressant for one sulfide minerai and/or activator for a different sulfide minerai under a common set of conditions. For example, under one set of conditions, the sulfoxy reagent activâtes flotation of copper, lead, and zinc sulfides and

under a different set of conditions activâtes flotation only of copper sulfides and not lead and zinc sulfides. In another example, the sulfoxy reagent depresses flotation of zinc sulfide but not lead sulfide.

In other examples, the concentrate and tailings can each include different valuable métal sulfide minerais. The valuable métal in the tailings can later be isolated from any gangue sulfide minerais by subséquent flotation stages. Examples of base métal mixed sulfide ores amenable to the process dîscussed herein include copper-gold (e.g., as calaverite (AuTe2) or sylvanite (Au,Ag)Te2)), copper-gold-sîlver (e.g., as acanthite (Ag2S), sylvanite (Au,Ag)Te2), pyrargyrite (Ag3SbS3), and proustite (Ag3AsS3)), lead (e.g., as galena (PbS), altaite (PbTe), boumonite (PbCuSbS3), jamesonite (Pb4FeSb6S14), and cylindrite (Pb3Sn4FeSb2S14))-zinc (e.g., as sphalerite (ZnS))-copper, copper-zinc, and copper-molybdenuin. Massive sulfide ores, for instance, usually contain sulfides of three or more valuable metals as well as gangue sulfide minerais, such as pyrite.

The présent invention, in various embodiments, configurations, or aspects, includes components, methods, processes, Systems and/or apparatus substantially as depicted and described herein, including various embodiments, configurations, aspects, subcombinations, and subsets thereof. Those of skill in the art will understand how to tnake and use the présent invention after understanding the présent disclosure. The présent invention, in various embodiments, configurations, and aspects, includes providing devices and processes in the absence of items not depicted and/or described herein or in various embodiments, configurations, or aspects hereof, including in the absence of such items as may have been used in previous devices or processes, e.g., for improving performance, achieving ease and\or reducîng cost of implémentation.

The foregoing discussion of the invention has been presented for purposes of illustration and description. The foregoing is not intended to limit the invention to the form or forms disclosed herein. In the foregoing Detailed Description for example, various features of the invention are grouped together in one or more embodiments, configurations, or aspects for the purpose of streamlining the disclosure. The features of the embodiments, configurations, or aspects of the invention may be combined in alternate embodiments, configurations, or aspects other than those discussed above. This method of disclosure is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than ail features of a single foregoing disclosed embodiment, configuration, or aspect. Thus, the following claims are hereby incorporated into this Detailed Description, with each claim standing on its own as a separate preferred embodiment of the invention.

Moreover, though the description of the invention has included description of one or more embodiments, configurations, or aspects and certain variations and modifications, other variations, combinations, and modifications are within the scope of the invention, e.g., as may be within the skill and knowledge of those in the art, after understanding the présent disclosure. It is intended to obtain rights which include alternative embodiments, configurations, or aspects to the extent permitted, including alternate, interchangeable and/or équivalent structures, functions, ranges or steps to those claimed, whether or not such alternate, interchangeable and/or équivalent structures, functions, ranges or steps are

Claims (14)

1. A process, comprising:

providing a slurried valuable metal-containing feed material comprising at least one of a copper sulfide and molybdenum sulfide minerai as a valuable métal sulfide minerai, an iron sulfide minerai as a gangue sulfide minerai, and one or more of fresh water, brackish water, and sait water;

aerating, with a molecular oxygen-containing gas, the slurried valuable metalcontaining feed material to form an aerated feed material;

thereafter contacting the aerated feed material with a sulfoxy reagent to form a treated feed material; and floating the treated feed material to form a concentrate comprising at least most of the at least one of a copper sulfide and molybdenum sulfide minerai in the aerated feed material and tailings comprising at least about 40% of the iron sulfide minerai in the aerated feed material.

2. The process of claim 1, wherein the at least one of a copper sulfide and molybdenum sulfide is a copper sulfide and wherein the slurried valuable metal-containing feed material comprises buffered and/or saline water.

3. The process of claim 1, wherein, prior to the floating step, the slurried valuable metal-containing feed material is not contacted with an extemally generated nonoxidizing gas to lower a dissolved molecular oxygen content of the slurried valuable metal-containing feed material.

4. The process of claim 1, wherein the at least one of a copper sulfide and molybdenum sulfide is a copper sulfide and wherein at least about 50 g/t of the sulfoxy reagent is added to the valuable metal-containing feed material.

5. The process of claim 1, wherein the flotation step is cleaner flotation, wherein the valuable metal-containing feed material is a rougher concentrate of rougher flotation, wherein the at least one of a copper sulfide and molybdenum sulfide is a copper sulfide, wherein the valuable metal-containing feed material is free of contact with a sulfoxy reagent prior to rougher flotation, wherein the rougher concentrate is subjected to secondary comminution before the flotation step, wherein the treated feed material has a pH of less than pH 8, and wherein sulfoxy reagent is contacted with the valuable metalcontaining feed material during secondary comminution and after aération,.

6. The process of claim l, wherein the aerated feed material has a dissolved molecular oxygen content of more than 2 ppm in the thereafter contacting step, wherein

5 the sulfoxy reagent is one or more of an ammonium, hydrogen, alkali, or alkaline earth métal sulfite, bisulfite, and metabisulfite, wherein the slurried valuable metal-contaîning feed material is substantially free of pH adjustment before and during flotation, wherein the water has at least one of a salinity of about 0.01% or more and a total dissolved solids of at least about 10,000 mg/L, and wherein flotation is performed at a natural pH of the

10 treated feed material.

7. A process, comprising:

providing a slurried valuable metal-containing feed material comprising a valuable métal sulfide minerai and a second sulfide minerai to be separated from the valuable métal sulfide minerai, wherein the valuable métal sulfide minerai is at least one of a copper

15 sulfide and molybdenum sulfide, and wherein the slurried valuable metal-containing feed material comprises water having at least one of a salinity of about 0.01% or more and a total dissolved solids of at least about 10,000 mg/L;

aerating, with a molecular oxygen-containing gas, the slurried valuable metalcontaining feed material to form an aerated feed material;

20 contacting at least a portion of the slurried valuable metal-containing feed material with a sulfoxy reagent; and floating the aerated and sulfoxy reagent-containing slurry to form a concentrate comprising at least about 40% of the valuable métal sulfide minerai and tailings comprising at least about 40% of the other sulfide minerai in the aerated and sulfoxy

25 reagent-containing slurry.

8. The process of claim 7, wherein the at least one of a copper sulfide and molybdenum sulfide is a copper sulfide, wherein the second sulfide is an iron sulfide minerai, wherein the iron sulfide minerai is at least one of pyrite, marcasite, arsenopyrite, and pyrrhotite, wherein the flotation step is cleaner flotation, wherein the mill is in a

30 regrind circuit, wherein the valuable metal-containing feed material is a rougher concentrate of rougher flotation, wherein the valuable metal-containing feed material is free of contact with a sulfoxy reagent prior to rougher flotation, and wherein more than 200 g/t of sulfoxy reagent is added to the valuable metal-containing feed material.

9. The process of claim 7, wherein, prior to the floating step, the slurried valuable metal-containing feed material is not contacted with an extemally generated nonoxidizing gas to lower a dissolved molecular oxygen content of the slurried valuable metal-containing feed material.

10. The process of claim 7, wherein the at least one of a copper sulfide and molybdenum sulfide is a copper sulfide, wherein the second sulfide minerai comprises a valuable métal other than copper and molybdenum, wherein the aerated feed material is the at least a portion of the slurried valuable metal-containing feed material, and wherein at least about 100 g/t of sulfoxy reagent is added to the valuable metal-containing feed material, and wherein a dissolved molecular oxygen content of the aerated material is at least about 5 ppm.

11. The process of claim 7, wherein the slurried valuable metal-containing feed material comprises at least one of sait water and brackish water and wherein a dissolved molecular oxygen content of the slurried valuable metal-containing feed material during the contacting step is more than 2 ppm.

12. The process of claim 7, wherein the at least one of a copper sulfide and molybdenum sulfide is a copper sulfide, wherein the second sulfide minerai comprises a valuable métal other than copper and molybdenum, wherein the sulfoxy reagent is one or more of an ammonium, hydrogen, alkali, or alkaline earth métal sulfite, bisulfite, and metabisulfite, wherein at least about 50 g/t of sulfoxy reagent is added to the valuable metal-containing material, and wherein the slurried valuable metal-containing feed material is substantially free of pH adjustment before and during flotation.

13. The process of claim 7, wherein the valuable métal sulfide and second sulfide minerai are substantially free of pH modification before the floating step, wherein the at least one of a copper sulfide and molybdenum sulfide is a copper sulfide, wherein the second sulfide is a sulfidic gangue minerai, wherein the sulfidic gangue minerai is at least one of pyrite, marcasite, arsenopyrite, and pyrrhotite, wherein a pl i of the valuable métal sulfide and second sulfide is the natural pH, wherein, prior to the floating step, the slurried valuable metal-containing feed material is not contacted with an extemally generated non-oxidizing gas to lower a dissolved molecular oxygen content of the slurried valuable metal-containing feed material, and wherein the aerated feed material has a pH of less than pH 8.5.

14. The process of claim 7, wherein the at least one of a copper sulfide and molybdenum sulfide is a copper sulfide, wherein the aerated feed material has a pH of less than pH 8.5, wherein the water is at least one of sait water and brackish water, wherein a dissolved molecular oxygen content of the aerated feed material during the contacting step is more than 2 ppm, wherein the water comprises at least one of sait water and brackish 5 water, wherein the floating step is cleaner fiotation, wherein the sulfoxy reagent is added to a solution derived from the feed material in a mill, wherein the mill is in a regrind circuit, wherein the valuable metal-contaîning feed material is a rougher concentrate of rougher fiotation, wherein the valuable metal-containing feed material is free of contact with a sulfoxy reagent prior to rougher fiotation, wherein the sulfoxy reagent is one or 10 more of an ammonium, hydrogen, alkali, or alkaline earth métal sulfite, bisulfite, and metabisulfïte, wherein more than 100 g/t of sulfoxy reagent is added to the valuable metalcontaining feed material, and wherein the slurried valuable metal-containing feed material is substantially free of pH adjustment before and during fiotation.