Polycarbamide separation aids for mineral flotation

Abstract

Compositions and methods for the separation and recovery of one or more minerals from a mineral ore bulk material are provided. The compositions and methods include selectively depressing minerals utilizing polycarbamide as a separation aid. The polycarbamide reduces, or eliminates, the conventional use of depressants such as sodium hydrosulfide (NaSH) in mining flotation processes, including copper-molybdenum (Cu-Mo) separations.

Description

POLYCARBAMIDE SEPARATION AIDS FOR MINERAL FLOTATIONRELATED APPLICATIONS

[0001] This application claims priority to and any benefit of U.S. Provisional Application No. 63 / 691,396, filed on September 6, 2024, U.S. Provisional Application No. 63 / 691,417 filed on September 6, 2024, U.S. Provisional Application No. 63 / 691,430 filed on September 6, 2024, U.S. Provisional Application No. 63 / 712,104 filed on October 25, 2024, U.S. Provisional Application No. 63 / 712,125 filed on October 25, 2024, U.S. Provisional Application No. 63 / 712,139 filed on October 25, 2024, U.S. Provisional Application No. 63 / 744,033 filed on January 10, 2025, U.S. Provisional Application No. 63 / 744,057 filed on January 10, 2025, U.S. Provisional Application No. 63 / 744,071 filed on January 10, 2025, U.S. Provisional Application No. 63 / 744,099 filed on January 10, 2025, U.S. Provisional Application No. 63 / 744,119 filed on January 10, 2025, U.S. Provisional Application No. 63 / 744,131 filed on January 10, 2025, and U.S. Provisional Application No. 63 / 760,860 filed on February 20, 2025, the contents of which are incorporated herein by reference in their entireties.FIELD

[0002] The invention relates to methods and compositions and for the separation and recovery of one or more minerals from a mineral ore bulk material. More particularly, the invention relates to methods of selectively depressing minerals utilizing a separation aid containing a polycarbamide. A polycarbamide reduces, or eliminates, the conventional use of inorganic depressants such as sodium hydrosulfide (NaSH) in mining flotation processes, including copper-molybdenum (Cu-Mo) separations.BACKGROUND

[0003] Flotation methods, such as froth flotation, are utilized in the mining industry to selectively extract a desired mineral from a mineral ore bulk material. Industrial mining flotation processes generally include the separation of a bulk material into a floated concentrateand flotation tailings. For example, copper-molybdenum (Cu-Mo) operations seek to selectively separate and recover the small amount of high-value molybdenum (Mo) minerals from a mineral ore bulk material primarily comprised of copper sulfide minerals, pyrite, and non-sulfide gangue. The minerals are referred to by the valuable metal in the mineral itself.

[0004] Conventionally, Cu-Mo mining flotation mills have utilized inorganic depressants such as sodium hydrosulfide (NaSH) to selectively depress the copper minerals (Cu) from the mineral ore bulk material. Molybdenum minerals (Mo) and copper minerals (Cu) are inherently hydrophobic, and float in a flotation system. Thus, to separate out the Mo from the Cu in froth flotation, the Cu minerals first must be depressed. In conventional processes, NaSH forms hydrogen sulfide ions and desorbs collectors from Cu minerals, resulting in the depression of Cu. In addition to NaSH, other inorganic reagents are also conventionally used as separation aids to separate Cu from Mo in Cu-Mo mining processes, including sodium sulfide (Na?S), Nokes reagent (P2Ss / NaOH), and sodium cyanide (NaCN).

[0005] That said, these conventional depressant chemicals, including NaSH, exhibit hazards such as strong odor, flammability, and the potential generation of toxic hydrogen sulfide (H2S) gas and / or toxic hydrogen cyanide gas. Additionally, these conventional depressant chemicals create manufacturing and logistical challenges. The requisite dosage of NaSH to depress Cu effectively is significant, thus requiring a high consumption of NaSH in industrial facilities, and resulting in substantial cost related to the transportation, handling, and storage of large quantities of hazardous chemicals.

[0006] As such, a need exists for methods of selectively depressing minerals in mining flotation processes with a separation aid that reduces, or eliminates, the use of conventional hazardous inorganic reagents such as NaSH, while still maintaining the requisite functionality of a depressant in mining technologies, particularly Cu-Mo mining technologies. The replacement of conventional depressants such as NaSH would provide substantial economic,environmental, health, and safety benefits to the mining industry, including the Cu-Mo mining industry.SUMMARY

[0007] This invention relates to methods and compositions for the separation and recovery of one or more minerals from a mineral ore bulk material. The methods include selectively depressing minerals utilizing a separation aid containing polycarbamide, which reduces, or eliminates, the conventional use of separation aids such as sodium hydrosulfide (NaSH) in mining flotation processes, including copper-molybdenum (Cu-Mo) separations.

[0008] The method for the separation and recovery of one or more minerals from a mineral ore bulk material includes the steps of: forming an aqueous pulp comprising water, a mineral ore bulk material, and a separation aid; agitating and floating the aqueous pulp to form a floated mineral concentrate and flotation tailings; and separately recovering the floated mineral concentrate and flotation tailings. The aqueous pulp may be formed by adding the mineral ore bulk material to the water to form a slurry; mixing the slurry; and adding the separation aid to the slurry while mixing to form the aqueous pulp. The step of agitating and floating the aqueous pulp comprises introducing air at a suitable flow rate to the aqueous pulp thereby floating the floated mineral concentrate.

[0009] In certain aspects, the floated mineral concentrate comprises molybdenum and the flotation tailings comprise copper, iron (Fe), or combinations thereof.

[0010] A separation aid of the invention comprises a polycarbamide formed from the reaction products of formaldehyde and urea. The hydrophilic polymer-modified polycarbamide has a mole ratio of formaldehyde to urea [ .e., formaldehyde:(urea)] is from 0.5 to 2.5, or from 0.8 to 2.0.[OH] In certain aspects, the polycarbamide is an alkylated polycarbamide comprising the reaction product of a urea compound and an alkylating agent. The alkylating agent may be amonohydric aliphatic alcohol containing 1 to 4 carbon atoms, such as a methylating agent. If present, the alkylating agent may be included in an amount from 0.1 wt.% to 30 wt.%, based on the weight of the separation aid.

[0012] A separation aid of the invention may optionally include 0.01 wt.% to 30 wt.% a biopolymer. The biopolymer may comprise one or more of a lignin-based polymer, a polysaccharide, a starch, a hydrocolloid, flour, a soy protein, or combinations thereof. The lignin-based polymer may comprise a lignosulfonate, such as sodium lignosulfonate, calcium lignosulfonate, ammonium lignosulfonate, magnesium lignosulfonate, or mixtures thereof. Exemplary hydrocolloids include anionic hydrocolloids, nonionic hydrocolloids, or combinations thereof. Exemplary starches include natural starch, modified starch, or combinations thereof.

[0013] Alternatively, or in addition to the biopolymer, a separation aid of the invention may be modified with a hydrophilic polymer. The hydrophilic polymer may be acrylamide polymer, such as, for example, N-methylolacrylamide polymer, polyacrylamide, sodium polyacrylate, potassium polyacrylate, poly(N,N-dimethylacrylamide), sodium polymethacrylate, or combinations thereof. If present, the hydrophilic polymer may be included in the separation aid in an amount from 0.1 wt.% to 20 wt.%.

[0014] A separation aid of the invention may further include a sulfur compound as a performance enhancing supplement. The sulfur compound may include an ionizable thiol group. The sulfur compound may comprise a sulfite, a sulfate, a thiol -functional compound, a sulfide, a sulfamate, a sulfinic acid, or combinations thereof. In some aspects, the supplementary sulfur compound comprises a sulfide, a disulfide, a sulfinic ester, a thiocyanate, a thiocarboxylic acid, a thioester, a sulfinic acid, a dithiocarboxylic acid, a dithiocarboxylic acid ester, a sulfamate, a sulfamide, salts of any of the above, or combinations thereof.

[0015] A separation aid of the invention may further optionally include one or more supplemental depressants. If present, the supplemental depressant and polycarbamide may be pre-mixed prior to the addition of the separation aid to the aqueous pulp, or the components may be added separately. Exemplary supplemental depressants include thioglycolic acid (TGA) salts, ethylenediaminetetraacetic acid (EDTA) salts, mercaptosuccinic acid (MSA) salts, thioglycerin (TG) salts, or combinations thereof. Exemplary thioglycolic acid (TGA) salts include those selected from the group consisting of sodium thioglycolate (S-TGA), calcium thioglycolate (C-TGA), diethylenetriamine thioglycolate (D-TGA), ammonium thioglycolate (A-TGA), or combinations thereof. Exemplary mercaptosuccinic acid salts include disodium mercaptosuccinate (S-MSA), sodium thioglycerolate (S-TG), or combinations thereof. Exemplary EDTA salts include disodium EDTA (S-EDTA), sodium calcium edetate, and tetrasodium EDTA, or combinations thereof.

[0016] In some aspects, the supplemental depressant may further include one or more of sodium hydrosulfide (NaSH), sodium sulfide (Na?S), Nokes reagent, sodium cyanide (NaCN), or combinations thereof, although in certain instances, the separation aid may be free, or substantially free of sodium hydrosulfide (NaSH).

[0017] Aspects of the invention are further directed to the use of a polycarbamide or alkylated polycarbamide as a separation aid in a mineral ore separation process.DETAILED DESCRIPTION

[0018] The invention relates to methods for the separation and recovery of one or more minerals from a mineral ore bulk material, including methods of selectively depressing minerals utilizing a separation aid containing a polycarbamide, optionally modified with an alkyl group, a biopolymer, and / or a hydrophilic polymer. A “separation aid” is a compound or composition that facilitates the separation of minerals in a flotation mining process. The term “separation aid” may thus be understood to encompass mining reagents, depression agents,collection agents, and compositions containing them as well as any commonly used term to indicate such an agent for use in froth flotation processes. While describing certain aspects of the mining flotation methods and compositions in detail, the description is to be considered exemplary and is not intended to be limited to the invention.Methods for Separation and Recovery of Minerals from Mineral Ore

[0019] The invention provides a method for the separation and recovery of one or more minerals from a mineral ore bulk material. The method includes the steps of: 1) forming an aqueous pulp comprising water, a mineral ore bulk material, a separation aid comprising a polycarbamide, and optionally one or more mineral collectors; 2) agitating and floating the aqueous pulp to form a floated mineral concentrate and flotation tailings; and 3) separately recovering the floated mineral concentrate and flotation tailings. As will be described in more detail below, the polycarbamide separation aid may be alkylated and may be modified with a biopolymer, a hydrophilic polymer, or each of a biopolymer and a hydrophilic polymer.

[0020] As a first step, a method of the invention forms an aqueous pulp containing water, a mineral ore bulk material, a separation aid, and optionally one or more mineral collectors. The separation aid contains or itself is polycarbamide. The aqueous pulp may be formed by methods known in the art, for example, by adding the mineral ore bulk material to water to form a slurry, mixing the slurry, and adding the separation aid and optional mineral collector to the slurry while mixing to form the aqueous pulp. Prior to forming an aqueous pulp, the mineral ore bulk material may be subjected to a comminution process to produce smaller or finer mineral ore particles. The comminution process is not particularly limited, and may include any known methods of particle size reduction such as crushing, grinding, etc.

[0021] In general, the methods of the invention may be used with any mineral ore bulk material suitable for separation in flotation mining processes. The mineral ore bulk material may contain, inter alia, minerals including copper (Cu) and molybdenum (Mo) requiringseparation. The mineral ore bulk material may also be a copper-molybdenum (Cu-Mo) concentrate.

[0022] After forming the aqueous pulp, the method includes the step of agitating and floating the aqueous pulp to form a floated mineral concentrate and flotation tailings. Agitating the aqueous pulp, alone or enhanced with the introduction of air, can result in “froth” of air bubbles with minerals and optionally mineral collectors attached to the air bubbles. This froth forms all or part of the floated mineral concentrate. The optional mineral collectors may be included in the aqueous pulp to increase the hydrophobicity of the minerals to be floated, such as molybdenum (also referred to as a Mo collector). The mineral collectors may include, for example, liquid hydrocarbons, hydroxyamide, pine oil, kerosine, diesel, and the like.

[0023] The step of agitating and floating the aqueous pulp may comprise introducing a gas, such as air or nitrogen, into the aqueous pulp at a suitable flow rate to generate bubbles and agitating the aqueous pulp thereby causing a froth to form and floating a mineral concentrate. Conversely, the flotation tailings, which remain in the slurry, make up the residual of the mineral ore bulk material depressed using the separation aid and are not collected in the floated mineral concentrate.

[0024] Following the formation of the floated mineral concentrate and the flotation tailings, the method comprises separately recovering the floated mineral concentrate from the aqueous pulp. The particular equipment and procedure for recovering floated mineral concentrate is well known to those of skill in the art. For instance, the floated mineral concentrate may be periodically collected as froth that has accumulated on the surface of the aqueous pulp undergoing agitation. A suitable procedure for recovering the floated mineral concentrate is described in U.S. Patent No. 10,654,048.

[0025] The type of recovered floated mineral concentrate is not limited and will depend on the mineral ore bulk material undergoing separation by a mining flotation process.Accordingly, the recovered floated mineral concentrate may be any mineral suitable for separation in flotation mining processes. In one aspect, the floated mineral concentrate contains molybdenum (Mo). Similarly, the type of recovered flotation tailing is not limited, and will depend on the mineral ore undergoing separation by a mining flotation process. The recovered flotation tailing may then be any mineral suitable for separation in flotation mining processes. For example, the flotation tailing may contain copper (Cu) and / or iron (Fe) minerals. Polycarbamides

[0026] A separation aid of the invention contains, or is itself, a polycarbamide or an alkylated polycarbamide and functions to selectively depress one or more minerals in a flotation mining process. A poly carbamide is generally more hydrophilic relative to the mineral it is being used to depress. When the polycarbamide interacts with the mineral, it alters the relative wettability of the surface of the mineral making it more hydrophilic. This, in turn, acts to depress certain minerals during a flotation process.

[0027] The polycarbamide may be prepared using a one-, two-, three-, four, or more stage polymer synthesis process. The polymer synthesis stages may be completed in various steps, sequences, or synthesis routes. For instance, in a first exemplary synthesis route, a first stage forms a polycarbamide by the reaction of urea and a second stage includes the addition of a sulfur compound as a performance enhancing supplement. Optionally, additional stage(s) include the addition of alkylating agents, biopolymers, hydrophilic polymers, and / or supplemental depressants.

[0028] In a second exemplary synthesis route, a first stage may include the alkylation (e.g., methylation) of a urea compound, and a second stage forms a polycarbamide by the reaction of urea and formaldehyde, thereby forming an alkylated polycarbamide. Optionally, additional stage(s) include the addition of sulfur compounds, as performance enhancing supplements, hydrophilic polymers, biopolymers, and / or supplemental depressants.

[0029] For clarity purposes, the process will be described herein as a series of stages and steps, but it should be appreciated that the various steps and stages of the synthesis process may not necessarily occur stepwise, but rather in some instances may occur simultaneously or in situ.Preparation of a Polycarbamide

[0030] The methods of forming the polycarbamide are not limited and may include any known polymer syntheses. A polycarbamide may be formed via a two-step process, including a first step of combining formaldehyde and urea; and a second step of controlling the degree of polymerization of the polycarbamide.

[0031] In an exemplary method, the first step of forming a polycarbamide includes charging formaldehyde into a reactor and adjusting the pH of the formaldehyde solution to a neutral or alkaline pH. The formaldehyde may be paraformaldehyde (z.e., 100% formaldehyde), or aqueous formaldehyde having a concentration up to 60% formaldehyde, including, for example, formaldehyde concentrations of 20%-58%, 25%-55%, and 30%-53%. Aqueous formaldehyde having an amount of formaldehyde greater than 20% is preferred. When paraformaldehyde is used, an amount of water may also be charged to the reactor to form an aqueous formaldehyde solution. The pH of the formaldehyde solution is adjusted to a neutral or alkaline pH, for example, a pH of 7 to 9, such as, for example, a pH of 7.2 to 8.4, or about 7.4 to 8.2, or about 7.5. Any pH adjuster known in the art may be used. Exemplary pH adjusters include, but are not limited to, triethanolamine (TEA), sodium hydroxide (NaOH), sulfuric acid, formic acid, and the like.

[0032] A first urea charge (Ui) is added to the formaldehyde solution. The first urea charge (Ui) may constitute the total urea (U) of the polycarbamide. In other aspects, the total urea (U) may include multiple urea charges at different steps in the synthesis process. The reaction is heated (via exotherm and an additional heat source) and held at an elevated temperature; forexample, at a temperature from 90°C to 110°C, from 90°C to 107°C, from 95°C to 105°C, or from 99°C to 102°C. The reaction is held for a time sufficient to form various (hydroxymethyl)urea intermediates. For example, the reaction may be held for a period of 30 to 60 minutes, 30 to 45 minutes, or 40 to 50 minutes.

[0033] The second step of forming a polycarbamide controls the degree of polymerization via targeted adjustments to the system. The synthesis of a polycarbamide may take place under acidic conditions, including at a pH of less than 7, such as a pH of 3 to 6, a pH of 3.5 to 5.5, or a pH of 4.5 to 5.5. The pH may be adjusted using pH adjusters known in the art such as the exemplary pH adjusters mentioned above.

[0034] The synthesis of the polycarbamide ends at a target viscosity on the Gardner-Holdt (G-H) bubble viscosity scale, including a viscosity of A to UV, of D to X, or of K to V, for example. The target viscosity may be reached by adjusting the temperature and / or pH of the system. The temperature preferably remains between 90°C and 110°C during the viscosity adjustment stage. The pH of the system at the viscosity adjustment stage may be from 7 to 9, such as, for example, a pH of 7.2 to 8.4, or about 7.4 to 8.2, or about 7.5. The pH may be adjusted as known in the art using exemplary pH adjusters such as those mentioned above. After reaching the target viscosity, the system may be cooled to a temperature of from 50°C to 90°C, from 50°C to 70°C, from 55°C to 65°C, or from 55°C to 60°C.

[0035] Optionally, a second urea charge (U2) is added during the synthesis of the poly carbamide. The total urea (U) may include the first urea charge (Ui) plus the second urea charge (U2), z.e., U = Ui + U2. The batch temperature may be further cooled to a temperature of from 25°C to 60°C, from 25°C to 45°C, from 25°C to 40°C, including approximately 20°C to 26°C. The pH of the batch may likewise be adjusted as needed. The system may be held with continuous stirring for a time sufficient to dissolve the second urea, for example for from30 to 60 minutes, from 5 to 30 minutes, or from 5 to 15 minutes.

[0036] Accordingly, a polycarbamide useful in the invention is the reaction products of formaldehyde and urea. The molar ratio of formaldehyde to the combination of total urea z.e., [formaldehyde :urea], [F / U], may range from 0.5 to 2.5, for example, from 0.6 to 2.3, from 0.8 to 2.1, or from 0.8 to 2.0. A polycarbamide may also be adjusted to any desired degree of polymerization as is known in the art. The degree of polymerization can be adjusted by utilizing a different target end viscosity, a different F / U mole ratio, and / or a different manufacturing pH range.

[0037] An optional stabilizing agent may be included, such as one or more monomeric polyols. Suitable monomeric polyols may include, for example, diols, triols, tetrols, and mixtures thereof. The monomeric polyols may be sugar alcohols (e.g., sorbitol, glycerol, and glycols (e.g., ethylene glycol, diethylene glycol, propylene glycol, and the like)). The stabilizing agent may be optionally added at any stage of the polymer synthesis.Alkylating Agent

[0038] In the multi-stage polymer synthesis process, an alkylating agent, or mixture of alkylating agents, may optionally be reacted with a urea compound or a formed polycarbamide to form an alkylated polycarbamide separation aid. Accordingly, the separation aid of the invention may be an alkylated polycarbamide separation aid.

[0039] The method of producing the alkylated polycarbamide is not particularly limited, and the synthesis stages may occur in various orders. For instance, an alkylating agent may be added directly to a polycarbamide composition that was formed in a prior stage. Alternatively, the alkylating agent may be reacted with a urea compound in a first step, followed by the formation of a polycarbamide by reacting the alkylated urea compound and formaldehyde. The term “alkylating agent” describes a chemical compound having a moiety suitable for transferring an alky group another molecule or compound.

[0040] The alkylating agent may comprise, or consists of, a C1-C4 alkylating agent, such as a monohydric aliphatic alcohol containing 1 to 4 carbon atoms. Exemplary monohydric aliphatic alcohols include methanol, ethanol, propanol, butanol, isopropanol, n-butanol, secondary butanol, tertiary butanol, or a mixture thereof. In certain aspects, the alkylating agent may be a methylating agent such as methanol, iodomethane, dimethyl sulfate, dimethyl carbonate, methyl triflate, and the like. In other aspects, the alkylating agent may comprise a propylating agent, ethylating agent, butylating agent, and the like.

[0041] If present, the alkylating agent may be included in the separation aid in an amount such that a mole ratio of alkylating agent to urea z.e., [alkylating agent:urea], may range from 0.01 to 3.0, including, for example, from 0.05 to 2.0, and 0.1 to 1.0.

[0042] Within the molar ratios provided above, the amount of alkylating agent included in the separation aid may be defined in terms of weight percent, based on the total weight of the separation aid. In this regard, the alkylating agent may be included in an amount from 0.1 wt.% (weight percent) to 50 wt.%, based upon the total weight of the separation aid, such as, for example, from 0.1 wt.% to 40 wt.%, from 0.1 wt.% to 30 wt.%, from 0.5 wt.% to 30 wt.%, from 0.8 wt.% to 25 wt.%, from 0.2 wt.% to 10 wt.%, from 0.5 wt.% to 8 wt.%, or from 1 wt.% to 6 wt.%, based upon the total weight of the separation aid.

[0043] According to a first exemplary synthesis route, urea and formaldehyde are reacted at a neutral or alkaline pH in an excess of formaldehyde, forming the intermediate urea compound (hydroxymethyl)urea. The urea and formaldehyde may be present in a mole ratio of about 1.1 to 5, including, for example, 1.5 to 4, or 2.0 to 3.5, to form various (hydroxymethyl)urea intermediates, such as bis(hydroxymethyl)urea. An alkylating agent, or mixture of alkylating agents, is introduced into the batch at an elevated temperature and a neutral or alkaline pH in the range of 7 to 9, such as, for example, a pH of 7.2 to 8.4, or about 7.4 to 8.2, or about 7.5. The elevated temperature may range from about 70°C to about 95°C,or from about 75°C to about 90°C and the composition may be mixed or otherwise agitated for a period of time sufficient to alkylate the (hydroxymethyl)urea, such as, for example, from 10 minutes to 80 minutes or 15 minutes to 50 minutes. The alkylated (hydroxymethyl)urea compound may then be further reacted in a following synthesis stage with formaldehyde, forming alkylated polycarbamide.

[0044] According to a second exemplary synthesis route, an alkylating agent, or mixture of alkylating agents, is added to a polycarbamide mixture after formation thereof and the alkylating agent(s) and polycarbamide are mixed under neutral or alkaline conditions (i.e., 7.0 - 9.0). The alkylating agent may be added to the polycarbamide at an elevated temperature in the range from about 90°C to about 110°C, or from about 95°C to about 105°C and held for a period of time to ensure methylation of the poly carbamide, such as for a period of 1 to 5 hours, or 2 to 4.5 hours, or 2.5 to 4 hours.Hydrophilic Polymer

[0045] Optionally, the synthesis process may further include the addition of one or more hydrophilic monomers that are polymerized during the synthesis of the polycarbamide to form a hydrophilic polymer-modified polycarbamide separation aid. Accordingly, a separation aid useful in the invention may include a polycarbamide or alkylated polycarbamide, optionally modified with a hydrophilic polymer.

[0046] Upon polymerization, the hydrophilic polymer may be included in the separation aid in an amount from 0.1 wt.% (weight percent) to 20 wt.%, based upon the total weight of the separation aid, such as, for example, from 0.05 wt.% to 18 wt.%, from 0.075 wt.% to 15 wt.%, from 0.1 wt.% to 12 wt.%, from 0.25 wt.% to 10 wt.%, from 0.5 wt.% to 8 wt.%, or from 1 wt.% to 6 wt.%, based upon the total weight of the separation aid. In some aspects, the hydrophilic polymer is included in the separation aid in an amount from 0.5 wt.% to 10 wt.%, based on the total weight of the separation aid.

[0047] The hydrophilic polymer comprises the reaction product of a hydrophilic monomer.In some aspects, the hydrophilic polymer is formed via radical polymerization of a hydrophilic monomer. Exemplary hydrophilic monomers include, without limitation, acrylamide monomers, acrylic acid, methacrylic acid, and the like. The hydrophilic monomer may comprise, or consist of, an acrylamide monomer. Exemplary hydrophilic polymers include, without limitation, N-methylolacrylamide polymer, poly(N,N-dimethylacrylamide), polyacrylamide, sodium polyacrylate, potassium polyacrylate, sodium polymethacrylate, potassium polymethacrylate, or combinations thereof. The hydrophilic polymer may comprise, or consist of, an acrylamide polymer. The hydrophilic polymer may comprise, or consist of, N-methylolacrylamide polymer.

[0048] The method for adding a hydrophilic polymer to the polycarbamide solution is not particularly limited. In certain aspects, the method includes adding hydrophilic monomer(s) to the reactor during formation of the poly carbamide. For example, an acrylamide monomer (e.g., N-methylolacrylamide or nMA) may be added during the polycarbamide synthesis process and mixed under acidic conditions. Upon incorporation of an initiator, the acrylamide monomer may undergo radical polymerization, forming the hydrophilic polymer (e.g., polynMA). The initiator may comprise any initiator commonly used in the art for radical polymerization, including peroxide or azo compounds. One exemplary initiator that would be suitable for use in the aforementioned reaction is ammonium persulfate. The initiator may be included in the liquid batch solution in an amount (solids) of about 0.001 wt. wt.% - 2.0%, such as 0.01 wt.% - 0.5 wt.%.

[0049] The incorporation of the hydrophilic polymer into the polycarbamide solution improves the storage stability of the final polymer compound. The hydrophilic monomer may be added to the reactor at an elevated temperature and a pH in the range of 7 to 9, such as, for example, a pH of 7.2 to 8.4, or about 7.4 to 8.2, or about 7.5. The elevated temperature may range from70°C-95°C, or from 75°C-90°C and the composition may be mixed or otherwise agitated for 10 minutes to 60 minutes or 20 minutes to 50 minutes.Biopolymer

[0050] Optionally, the polycarbamide separation aid may be further modified by a biopolymer or mixture of biopolymers. Thus, if present, the method of forming a polycarbamide includes the addition of a biopolymer or a mixture of biopolymers to the polycarbamide to form a biopolymer-modified polycarbamide separation aid, or in some aspects, a biopolymer and hydrophilic polymer-modified polycarbamide separation aid. Accordingly, a separation aid useful in the invention may include a polycarbamide or alkylated polycarbamide, optionally modified with a hydrophilic polymer, a biopolymer, or each of a hydrophilic polymer and a biopolymer.

[0051] The biopolymer may be included in the separation aid in an amount from 0.01 wt.% (weight percent) to 30 wt.%, based upon the total weight of the separation aid, such as, for example, from 0.05 wt.% to 25 wt.%, from 0.075 wt.% to 20 wt.%, from 0.1 wt.% to 18 wt.%, from 0.25 wt.% to 15 wt.%, from 0.5 wt.% to 12 wt.%, from 0.75 wt.% to 10 wt.%, from 0.9 wt.% to 8 wt.%, or from 1 wt.% to 5 wt.%, based upon the total weight of the separation aid.

[0052] The method for adding a biopolymer to the polycarbamide solution is not particularly limited. For example, one or more biopolymer(s) may be added to the polycarbamide during the synthesis process and mixed under neutral or alkaline conditions. The biopolymer may be dispersed in the polycarbamide solution and may incorporate within the polycarbamide via hydrogen bonding. Such an incorporation of the biopolymer into the polycarbamide improves the storage stability of the final polymer compound. The biopolymer may be added to the polycarbamide at an elevated temperature and a pH in the range of 7 to 9, such as, for example, a pH of 7.2 to 8.4, or about 7.4 to 8.2, or about 7.5. The elevatedtemperature may range from 70°C-95°C, or from 75°C-90°C and the composition may be mixed or otherwise agitated for 10 minutes to 60 minutes or 20 minutes to 50 minutes.

[0053] The biopolymer may comprise, or consist of lignin-based polymers, a polysaccharide, a starch, a hydrocolloid, or combinations thereof. The lignin-based polymers may comprise, for example a lignosulfonate, such as, for example, sodium lignosulfonate, calcium lignosulfonate, ammonium lignosulfonate, magnesium lignosulfonate, and the like. The hydrocolloid may comprise an anionic hydrocolloid, a nonionic hydrocolloid, or combinations thereof. Exemplary anionic hydrocolloids include, without limitation, sodium alginate (ALG), a xanthan gum (XG), carrageenan, high-methoxy pectin (HMOP), low- methoxy pectin (LMOP), and carboxymethyl cellulose (CMC). Exemplary nonionic hydrocolloids include, without limitation, arabic gum (AG), a guar gum, locust bean gum, konjac glucomannan, and hydroxypropyl methyl cellulose (HPMC).

[0054] The biopolymer may comprise, or consist of a starch, carboxymethylcellulose (CMC), a guar gum, a xanthan gum, flour, a soy protein, or combinations thereof. The starch may be a natural starch and / or a modified starch. Exemplary natural starches include, without limitation, corn starch, potato starch, tapioca starch, arrowroot, and wheat rice. Exemplary modified starches include, without limitation, a cationic starch, an anionic starch, a zwitterionic starch, and a carboxylated starch. Exemplary guar gums include, without limitation, a natural guar gum, a cationic guar gum, and an anionic guar gum. Exemplary xanthan gums include, without limitation, a natural xanthan gum, a cationic xanthan gum, and an anionic xanthan gum. The flour may comprise a natural flour, a cationic flour, or combinations thereof. The soy protein may comprise a natural soy protein, a cationic soy protein, an anionic soy protein, or combinations thereof.Sulfur Compound

[0055] A separation aid of the invention may further optionally include a sulfur compound. Accordingly, the separation aid may comprise, consist essentially of, or consist of a polycarbamide or alkylated polycarbamide, optionally modified with a hydrophilic polymer, a biopolymer, and / or a sulfur compound. The sulfur compound may serve as a performance enhancing supplement to the polycarbamide, ie., both to improve the stability of the polycarbamide, and to improve the depression of copper or other minerals in the disclosed methods.

[0056] The sulfur compound may comprise an organic or inorganic sulfur compound. The sulfur compound may comprise a compound having an ionizable thiol group. The sulfur compound may comprise, or consist of, a sulfite, a sulfate, a thiol -functional compound, a sulfide, a sulfamate, a sulfinic acid, or combinations thereof. The sulfur compound may comprise, or consist of, a sulfide, a disulfide, a sulfinic ester, a thiocyanate, a thiocarboxylic acid, a thioester, a sulfinic acid, a dithiocarboxylic acid, a dithiocarboxylic acid ester, a sulfamate, a sulfamide, salts of any of the above, or combinations thereof. The sulfur compound may comprise, or consist of, sodium metabisulfite, sodium bisulfite, sodium sulfite, sodium thiosulfate, thiourea, thiourea-formaldehyde polymer, sodium thiocyanate, sodium thiocarboxylate, methanethiol, ethanethiol, 2-mercaptoethanol, dimercaptosuccinic acid, cysteine, sodium sulfide, ammonium sulfide, sodium sulfamate, ammonium sulfamate, sodium sulfinate, or combinations thereof. In one aspect the sulfur compound is sodium metabisulfite, a thiourea-formaldehyde polymer, or a mixture thereof. In other aspects, the sulfur compound may comprise, or consist of, a thiourea derivative selected from the group consisting of cyclohexyl thiourea, phenylthiourea, and N-allylthiourea.

[0057] The sulfur compound may be included in the separation aid in an amount from 0.1 wt.% to 50 wt.%, based upon the total weight of the separation aid, including an amount from0.1 wt.% to 40 wt.%, from 0.1 wt.% to 30 wt.%, from 0.5 wt.% to 30 wt.%, from 0.2 wt.% to10 wt.%, based upon the total weight of the separation aid.Supplemental Depressants

[0058] A separation aid of the invention may also contain one or more supplemental depressants, which act or aid to disperse a particular mineral. In particular, the supplemental depressants aid in depressing certain minerals, such as copper and / or iron, during a flotation process to further separate such materials from those to be collected at the top of a separation vessel as part of the froth. The depressants are hydrophilic in nature and come into contact with the hydrophobic target minerals, such as copper. The copper-depressant complex that forms is now more hydrophilic than the original copper mineral. This hydrophilicity causes the surface- modified copper to remain in the aqueous pulp instead of attaching to hydrophobic bubbles, so the copper is depressed or settles out under the influence of gravity rather than floating to the top after attachment to a bubble.

[0059] Accordingly, the separation aid may comprise, consist essentially of, or consist of a polycarbamide or alkylated polycarbamide (optionally modified with a biopolymer and / or a hydrophilic polymer), an optional sulfur compound, and a supplemental depressant. Accordingly, a method for the separation and recovery of one or more minerals from a mineral ore bulk material may include the steps of pre-mixing a polycarbamide and one or more supplemental depressants to form a separation aid, followed by adding the separation aid to the aqueous pulp. Alternatively, or in addition to adding the supplemental depressant in a second step, the supplemental depressant may be incorporated during the formation of the polycarbamide, forming a one-part system.

[0060] A supplemental depressant or mixture of supplemental depressants may be included in a separation aid in an amount from 0.1 wt.% to 50 wt.%, based upon the total weight of the separation aid, such as from 0.5 wt.% to 40 wt.%, from 0.8 wt.% to 30 wt.%, from 0.8 wt.% to25 wt.%, from 0.2 wt.% to 10 wt.%, from 0.5 wt.% to 8 wt.%, including from 1 wt.% to 6 wt.%.

[0061] Exemplary supplemental depressants include, without limitation, thioglycolic acid (TGA) salts, ethylenediaminetetraacetic acid (EDTA) salts, mercaptosuccinic acid (MSA) salts, thioglycerin (TG) salts, or combinations thereof. The supplemental depressants are formed by neutralizing thioglycolic acid, ethylenediaminetetraacetic acid, mercaptosuccinic acid, or thioglycerin with a base or an amine to form sodium, calcium, amine, or ammonium salts. Exemplary bases include sodium hydroxide (NaOH) and calcium hydroxide (Ca(OH)2) and exemplary amines include amines, diamines, triamines, and tetramines, including diethylenetriamine (DETA) and ammonia. The supplemental depressants may be in a solid or aqueous form.

[0062] The supplemental depressants may comprise, or consist of, a thioglycolic acid (TGA) salt. The thioglycolic acid (TGA) salt may be an alkali metal TGA salt, an alkaline earth metal TGA salt, or an amine TGA salt. An amine thioglycolic acid (TGA) salt may be selected from the group consisting of amine-, diamine-, triamine-, and tetraamine- TGA salts, or combinations thereof. The thioglycolic acid (TGA) salt may be selected from the group consisting of mono- or di-sodium thioglycolate (S-TGA), calcium thioglycolate (C-TGA), diethylenetriamine thioglycolate (D-TGA), ammonium thioglycolate (A-TGA), or combinations thereof. In some aspects, the supplemental depressants may include a thioureaformaldehyde polymer formed from a reaction of thiourea and free formaldehyde.

[0063] The supplemental depressant may comprise, or consist of, an aminopolycarboxylic acid salt, as aminopolycarboxylic acid can form complexes with metal ions including, but not limited to, copper, iron, cobalt, and the like. The aminopoly carboxylic acid salt may be selected from the group consisting of ethylenediaminetetraacetic acid (EDTA) salts, diethylenetriaminepentaacetic acid (DTPA) salts, nitrilotriacetic acid (NTA) salts,iminodiacetic acid (IDA) salts, or combinations thereof. The supplemental depressant may comprise, or consist of, mono- or di-sodium EDTA (S-EDTA). The supplemental depressant may comprise, or consist of, mono- or di-sodium mercaptosuccinate (S-MSA), mono- or disodium thioglycerolate (S-TG), or combinations thereof. The supplemental depressant may also be one or more conventional depressants, such as, for example, sodium hydrosulfide (NaSH), sodium sulfide (Na2S), Nokes reagent, sodium cyanide (NaCN), or combinations thereof. In some aspects, the supplemental depressants may include a thiourea-formaldehyde polymer formed from a reaction of thiourea and free formaldehyde.

[0064] The polycarbamide of the invention (including any optional supplemental depressants) may be used in a mining flotation process in a dosage amount from 0.5 kg / T to 15 kg / T, based on the total weight of mineral ore bulk material (in tones “T”), including, for example, a dosage amount from 0.7 kg / T to 10 kg / T, or from 0.9 kg / T to 9 kg / T, or from 1 kg / T to 7 kg / T, or from 1.5 kg / T to 5.5 kg / T, including all endpoints and subranges therebetween. Preferably, the polycarbamide separating agent includes less than 5 kg / T of NaSH, such as, for example, less than 3 kg / T, less than 2.5 kg / T, less than 2 kg / T, less than 1.5 kg / T, or less than 1 kg / T NaSH.

[0065] The polycarbamide separation aid reduces, or eliminates, the use of conventional separation aid depressants such as NaSH, Na?S, Nokes reagent, and NaCN in mining flotation processes, including copper-molybdenum separations. Accordingly, in some aspects, the separation aid is devoid of NaSH, Na?S, Nokes reagent, and NaCN. In some aspects, the separation aid is devoid of NaSH.

[0066] A method for the separation and recovery of one or more minerals from a mineral ore bulk material may include preparing the supplemental depressant prior to mixing the hydrophilic polymer-modified polycarbamide and the supplemental depressant. Thus, a method is provided for depressing certain minerals, such as copper and iron, in mining flotationprocesses with a polycarbamide separation aid that reduces, or eliminates, the use of conventional hazardous reagents such as NaSH. NaSH produces hydrogen sulfide gas upon decomposition, which is highly toxic, flammable, corrosive, and malodorous. In contrast, the polycarbamide separation aid produces no gas and is not corrosive, thus allowing safer industrial handling.

[0067] Moreover, the biopolymer ingredients provide a sustainable alternative to the conventional use of NaSH. The biopolymer materials, if present, including, inter alia, starch and carboxymethylcellulose (CMC), are considered “natural” and the hydrophilic polymer materials if present, are environmentally friendly, and thus alleviate the concerns associated with conventional hazardous inorganic depressants.

[0068] Further, NaSH and other conventional inorganic depressants are oxidized and rendered ineffective when air is used to generate bubbles during the flotation process, causing mines to either use higher amounts of NaSH to compensate for the loss of efficacy due to oxidation, or else to use nitrogen gas to substantially reduce the oxidation of NaSH during flotation separation. However, the use of nitrogen gas adds cost to a flotation process and has been found to only minimally reduce NaSH (or other inorganic depressant) consumption. In contrast, poly carbamide separation aid of the invention is not readily oxidized by air, and thus there is no need to use nitrogen gas to generate bubbles during the flotation process. This provides both manufacturing efficiencies, as well as cost reductions. Additionally, the poly carbamide separation aid operates effectively across a pH range of 8 to 14, which increases the flexibility in flotation circuit conditions, compared to NaSH, which requires a narrow pH range (about 10.5-12.5) to maintain effectiveness.

[0069] It was surprisingly found that the biopolymer and / or hydrophilic polymer components change the rheology of the polycarbamide and improve the depression of copperand other minerals in a flotation mining process. This improved depression results in less copper recovery at the surface of the flotation cell.

[0070] The floated mineral concentrate recovery of the inventive method is the same, similar to, or improved over that of an otherwise identical method that uses NaSH as a sole separation aid. In some aspects, the flotation tailings recovery of the inventive method is the same, similar to, or improved over that of an otherwise identical method that uses NaSH as a sole separation aid. By providing equal or better depression of minerals, such as copper, at much lower polycarbamide separation aid treatment levels than conventional NaSH separation aids, the disclosed methods thus provide substantial economic benefits.

[0071] Unexpectedly, the polycarbamide separation aid provides high recovery rates of molybdenum and is at least comparable, if not improved, over the molybdenum recovery rates achieved through the use of NaSH. Percent recovery is defined as the total amount of molybdenum recovered after the flotation process (froth) divided by the total amount of molybdenum present in the mineral concentrate prior to the flotation process. The percent recovery of molybdenum is at least about 50%, at least about 55%, at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 77%, at least about 80%, at least about 85%, or at least about 90%.

[0072] Additionally, the use of the polycarbamide separation aid selectively removes molybdenum from the mineral concentrate without also recovering significant quantities of unwanted minerals, such as copper and iron. For instance, the percent recovery of copper as a contaminant in the molybdenum is less than about 20%, including, for example, 18% or less, 15% or less, 12% or less, 10% or less, 8% or less, 5% or less, and 4.5% or less. In some instances, the percent recovery of copper is between 1 and 15%, and preferably between 1 and 10%. As above, the percent recovery is the total amount of copper recovered after the flotationprocess (froth) divided by the total amount of copper present in the mineral concentrate prior to the flotation process.

[0073] In sum, as described, the invention relates the advantageous use of polycarbamide as a separation aid in a mineral ore separation process.EXAMPLES

[0074] The following examples are included for the purposes of illustration, and do not limit the scope of the general inventive concepts described herein.Polycarbamide with Sulfur CompoundExample 1-Preparation of Polycarbamide Separation Aids

[0075] Exemplary separation aids are prepared by synthesizing polycarbamide using a two- stage polymer process. The first stage includes the formation of a polycarbamide (including steps 1 and 2) and a second stage includes modification of the polycarbamide with a sulfur compound as a performance-enhancing supplement (including steps 3 and 4).

[0076] In step 1, formaldehyde is charged into a reactor and the pH is adjusted to 7.0-9.0, preferably 7.5-8.5. Aqueous formaldehyde (53% concentration) is used for the polymer synthesis. Alternatively, urea-formaldehyde concentrate (UFC) may be used for the polymer synthesis. An exemplary UFC is composed of 60 wt.% formaldehyde, 25 wt.% urea, and 15 wt.% water. The pH adjusters include triethanolamine (TEA) and 50% NaOH, as well as optionally 6% sulfuric acid, or 10% formic acid, as needed. Thereafter, a first urea charge (Ui) is added to the reactor, and the temperature is increased to 90°C-102°C, preferably 95°C- 100°C. The batch is held at this temperature for 10-30 minutes, preferably for 15-25 minutes. The F / Ui [i.e., formaldehyde:urea] mole ratio is from 1.5-4.0, preferably from 2.0-3.5. The urea and formaldehyde are reacted near neutral, at a pH range of 7.0-9.0, preferably 7.5-8.5, to form various hydroxymethyl urea intermediates (i.e., UF methylolation).

[0077] In step 2, the pH is decreased to an acidic range of 3.0-6.0, preferably to 4.5-5.5. The pH adjusters include acidic pH adjusters, such as 6% sulfuric acid, formic acid, and / or TEA, as needed. The temperature is held at 90°C-102°C, preferably 95°C-100°C during poly carbamide formation, preferably for about 15-25 minutes. The second step is ended at a target Gardner-Hol dt (G-H) bubble viscosity of “C-U,” preferably “E-M” by increasing the pH to about 7.0-9.0, preferably to 7.5-8.5, using TEA and 50% NaOH as the pH adjusters. A different degree of the polymerization can be achieved utilizing a different target end viscosity along with different F / Ui mole ratios and a different manufacturing pH range. The temperature is then adjusted to 50°C-80°C, preferably 55°C-70°C.

[0078] The second stage modifies the polycarbamide with sulfur compound(s), as performance-enhancing supplements (including steps 3 and 4).

[0079] In step 3, sodium metabisulfite is added to the batch in an amount of 0.1 wt.%-30 wt.%, preferably about 0.2 wt.%-10 wt.% and mixed for 5-60 minutes, preferably for 15-40 minutes, at 55°C-75°C, preferably to 60°C-70°C. The batch pH at this step is 7.0-9.0, preferably to 7.5-8.5. Different types of performance enhancing supplements other than sodium metabisulfite can be used, such as (but not limited to) sodium bisulfite, sodium sulfite, sodium thiosulfate, thiourea-formaldehyde polymer, etc.

[0080] When thiourea-formaldehyde polymer is used as a performance enhancing supplement at this step, thiourea (T) is charged into the batch and the pH is adjusted to 7.0-9.0 (preferably to 7.5-8.5) using TEA (triethanolamine) and 50% NaOH with or without 6% sulfuric acid. The batch is maintained at 50°C-75°C, preferably to 55°C-70°C, for 10-60 minutes (preferably for 20-50 minutes). Thiourea-formaldehyde polymer is formed from the reaction between thiourea and residual free formaldehyde. Optionally, if not enough free formaldehyde is present in the polymer system, 53% formaldehyde (Fi) may be charged into the batch. The pH is adjusted to 7.0-9.0 and maintained at a temperature of 50°C-75°C for 10-60 minutes. The mole ratio of (F + Fi) / (Ui + T) is around 1.0-3.5, preferably about 1.5-3.0. The levels of thiourea added to the batch are 0.1 wt.%-40 wt.%, preferably about 0.5 wt.%-30 wt.%.

[0081] In step 4, the reaction mixture is cooled to about 50°C-70°C, preferably to 55°C- 65°C, and a second urea charge (U2) is added to the reactor. The batch temperature is held at 40°C-60°C, preferably at 45°C-55°C, for 5-60 minutes, preferably for 15-45 minutes. The pH is adjusted to 7.0-9.5, preferably 7.5-9.0, using TEA and 6% sulfuric acid. The final F / (Ui +U2) mole ratio is from about 0.5-2.5, preferably from 0.8-2.0. The process for preparing the polycarbamide is completed by cooling the batch to 20°C-26°C.

[0082] A summary of the synthesis process of Example 1 is provided below in Table 1.Table 1 : Synthesis of Exemplary Polycarbamide Separation Aid

[0083] The chemical preparation of the exemplary polycarbamide separation aid,Compound C-l, is shown in Table 2.Table 2: Chemical Preparation of Exemplary Polycarbamide Separation Aid (wt.%)1: 53% concentration aqueous formaldehyde; 2: Triethanolamine; 3: 6%> sulfuric acid; 4: sodium metabisulfite.

[0084] The polycarbamide separation aid was examined for pH, solids, viscosity, color, and stability at both 4°C and 20°C-26°C (room temperature) storage, as summarized in Table 3. Viscosity was measured in accordance with ASTM D2983-03 using a Brookfield viscometer. Polymer stability was determined by the lack of phase separation or precipitation formation over time at 4°C and 20°C-26°C by visual observation. The exemplary polycarbamide separation aid demonstrated very good storage stability at 20°C-26°C, as well as 4°C storage stability, without any phase separation or precipitation.Table 3: Characteristics of Exemplary Poly carbamide Separation Aid1: room temperature (20°C-26°C).Example 2- Flotation Tests

[0085] Lab-scale flotation tests were conducted using the polycarbamide of Compound C- 1, as described in Example 1. The tests were conducted using a Metso D-12V flotation machine (manufactured by Metso Minerals Industries, Inc.). The minerals (Cu, Mo) from the floated concentrates as well as the tailing were measured by XRF (X-Ray Fluorescence) analyzer (manufactured by Thermo Scientific Niton XL3t GOLDD+). The Cu-Mo bulk concentrate was obtained from a copper mine in Arizona in the United States. The Cu-Mo concentrate containedtypical industry levels of Cu and Mo, which are around 20% to 30% copper and 0.2% to 1.0% molybdenum. The polycarbamide was employed with a low level of NASH as a supplemental depressant for the flotation tests. The poly carbamide and the supplemental depressants may be added separately, or they may be pre-mixed prior to the test and added as a one-part system.

[0086] The lab-scale flotation cell test was conducted according to the following procedure: (1) thaw 500 g of ore sample (Cu-Mo concentrate) in a warm water bath; (2) transfer the Cu-Mo bulk concentrate to a flotation cell; (3) start the impeller and adjust the speed to about 900 rpm; (4) control the pulp (Cu-Mo concentrate) level to be just below the target (not to overflow before the air) and mix the slurry; (5) check the pulp pH and ORP (Oxidation-Reduction Potential) prior to the addition of chemicals (control NaSH or exemplary polycarbamide); (6) slowly add chemicals to the flotation cell (e.g., control NaSH: ~ 550 mV ORP for full Cu depression); (7) add diesel as Mo collector if needed; (8) start and adjust air to the target flow rate (2 L / min or as needed); (9) float concentration 1 (first scrape of float bubbles) for 2 min in a collection pan (concentration 1) and measure the weight of the concentration 1 before the vacuum dry (mass pull 1); (10) record pH and ORP; (11) replace the collection pan and float concentration 2 for 3 min in a collection pan (concentration 2) and measure the weight of the concentration 2 before the vacuum dry (mass pull 2); and (12) record pH and ORP.

[0087] The XRF (X-Ray Fluorescence) measurement was conducted according to the following procedure: (1) vacuum-dry concentration 1 (float concentration 1) and concentration 2 (float concentration 2), as well as the tailing (depressed mineral), and measure the weight of each material (i.e., the total mineral concentrate is the sum of vacuum-dried concentration 1, vacuum-dried concentration 2, and vacuum-dried tailing); (2) oven-dry the materials overnight at 125°C, and measure the weight of each material; (3) measure and analyze the minerals fromeach material, and select Cu, Mo, Fe amounts on the XRF device; and (4) analyze Cu, Mo, Fe concentrations and obtain the recovery and grade of these minerals.

[0088] The results of the lab-scale flotation cell tests are summarized in Tables 4-6.Table 4: Flotation Cell Test Results (Study #1)Table 5: Flotation Cell Test Results (Study #2)Table 6: Flotation Cell Test Results (Study #3)

[0089] As detailed in Tables 4-6, the polycarbamide compositions described herein provided similar or better recovery of Cu and Mo as the control NaSH, and reduced or replaced NaSH at much lower chemical treatment levels. For example, the polycarbamide compositions with performance enhancing supplements (Candidate 1 and Candidate 2) demonstrated better Cu depression (lower Cu recovery value) than the control NaSH at a reduced chemical treatment level (0.6kg / T and 0.5 kg / T Composition C-l vs. 2kg / T NaSH) and was able toreplace 100% NaSH. As shown in Table 6, Candidate 4 replaced 100% of NaSH with Composition C-l and S-TGA at a 60% reduced treatment level and demonstrated better Cu depression. Each Candidate also exhibited sufficient Mo recovery.Example 3- Biopolymer Modified Polycarbamide Separation Aids

[0090] Exemplary separation aids are prepared by synthesizing biopolymer-modified polycarbamide using a two-stage polymer process. The first stage forms a polycarbamide (including steps 1 and 2) and the second stage modifies the polycarbamide with a biopolymer (including steps 3 and 4).

[0091] In step 1, formaldehyde is charged into a reactor and the pH is adjusted to 7.0-9.0, preferably 7.5-8.5. Aqueous formaldehyde (53% concentration) is used for the polymer synthesis. Alternatively, urea-formaldehyde concentrate (UFC) may be used for the polymer synthesis. An exemplary UFC is composed of 60 wt.% formaldehyde, 25 wt.% urea, and 15 wt.% water. The pH adjusters include triethanolamine (TEA) and 50% NaOH, as well as optionally 6% sulfuric acid, or 10% formic acid, as needed. Thereafter, a first urea charge (Ui) is added to the reactor, and the temperature is increased to 90°C-102°C, preferably 95°C- 100°C. The batch is held at this temperature for 10-30 minutes, preferably for 15-25 minutes. The F / Ui [i.e., formaldehyde:urea] mole ratio is from 1.5-4.0, preferably from 2.0-3.5. The urea and formaldehyde are reacted near neutral, at a pH range of 7.0-9.0, preferably 7.5-8.5, to form various (hydroxymethyl)urea intermediates (i.e., UF methylolation).

[0092] In step 2, the pH is decreased to an acidic range of 3.0-6.0, preferably to 4.5-5.5. The pH adjusters include acidic pH adjusters, such as 6% sulfuric acid, formic acid, and / or TEA, as needed. The temperature is held at 90°C-102°C, preferably 95°C-100°C during poly carbamide formation, preferably for about 15-25 minutes. The second step is ended at a target Gardner-Hol dt (G-H) bubble viscosity of “C-U,” preferably “E-M” by increasing the pH to about 7.0-9.0, preferably to 7.5-8.5, using TEA and 50% NaOH as the pH adjusters. Adifferent degree of the polymerization can be achieved utilizing a different target end viscosity along with different F / Ui mole ratios and a different manufacturing pH range. The temperature is then adjusted to 50°C-80°C, preferably 55°C-70°C.

[0093] The second stage includes the addition of a biopolymer (e.g., starch) to the polycarbamide in steps 3 and 4, thereby forming a biopolymer-modified polycarbamide separation aid.

[0094] In step 3, the temperature of the polycarbamide solution is adjusted to about 70°C- 95°C, preferably to 75°C-90°C, and a premixture of starch and water is added to the reactor. At this step, starch is dispersed first in the polycarbamide solution and de-natured (or disentangled), which causes the starch to swell. The batch temperature is held for 5-60 minutes, preferably 15-50 minutes, and the polymer viscosity increases over time. The starch level ranges from 0.01 wt.%-10 wt.%, preferably from 0.1 wt.%-4 wt.%. The pH at this step is 7.0- 9.0, preferably 7.5-8.5. After reaching the target viscosity (such as a target Gardner-Holdt (G- H) bubble viscosity of “E-X”), vacuum cooling or cooling water is applied to lower the temperature of the batch to 60°C-65°C. A water charge is employed at this step to adjust the solids content and the viscosity of the batch to the desired range.

[0095] In the step 4, the reaction mixture is cooled to about 50°C-70°C, preferably 55°C- 65°C, and the second urea (U2) is added to the reactor. The reaction mixture temperature is then further reduced to a temperature of 40°C-60°C, preferably 45°C-55°C and held for 5-60 minutes, preferably 15-45 minutes. The pH is adjusted to 7.0-9.5, preferably 7.5-9.0, using TEA and 6% sulfuric acid and / or 10% formic acid. The final (total F) / (total U), or F / (Ui + U2) mole ratio is from 0.5-2.5, preferably 0.8-2.0. The process for preparing the biopolymer- modified polycarbamide is completed by cooling the batch to 20°C-26°C.

[0096] A summary of the synthesis process of Example 3 is provided below in Table 7.Table 7: Synthesis of Exemplary Biopolymer-Modified Polycarbamide

[0097] The chemical preparation of the exemplary biopolymer-modified polycarbamide separation aid, Compound C-2, is shown in Table 8.Table 8: Chemical Preparation of Exemplary Biopolymer-Modified Poly carbamide Separation Aid (wt.%)1: 53% concentration aqueous formaldehyde; 2: Triethanolamine; 3: 6%> sulfuric acid; 4: cationic starch powder (premixed with water before charge).

[0098] The biopolymer-modified polycarbamide separation aid was thereafter examined for pH, solids, viscosity, color, and stability at both 4°C and 20°C-26°C (room temperature) storage, as summarized in Table 9. Viscosity was measured in accordance with ASTM D2983- 03 using a Brookfield viscometer. Polymer stability was determined by the lack of phase separation or precipitation formation over time at 4°C and 20°C-26°C by visual observation. The exemplary biopolymer-modified polycarbamide separation aids demonstrated very good storage stability at 20°C-26°C, as well as 4°C storage stability, without any phase separation or precipitation.Table 9: Characteristics of Exemplary Biopolymer-Modified Polycarbamide Separation Aid1: room temperature (20°C-26°C).Example 4- Flotation Tests

[0099] Lab-scale flotation tests were conducted using the biopolymer-modified polycarbamide, Compound C-2, as described in Example 3. The tests were conducted using a Metso D-12V flotation machine (manufactured by Metso Minerals Industries, Inc.). The minerals (Cu, Mo) from the floated concentrates as well as the tailing were measured by XRF (X-Ray Fluorescence) analyzer (manufactured by Thermo Scientific Niton XL3t GOLDD+). The Cu-Mo bulk concentrate was obtained from a copper mine in Arizona in the United States. The Cu-Mo concentrate contained typical industry levels of Cu and Mo, which are around 20% to 30% copper and 0.2% to 1.0% molybdenum. The biopolymer-modified polycarbamides were employed with a low level of NASH as a supplemental depressant for the flotation tests. The biopolymer-modified polycarbamide and the supplemental depressant may be added separately, or they may be pre-mixed prior to the test and added as a one-part system.

[0100] The lab-scale flotation cell test was conducted according to the following procedure: (1) thaw 500 g of ore sample (Cu-Mo concentrate) in a warm water bath; (2)transfer the Cu-Mo bulk concentrate to a flotation cell; (3) start the impeller and adjust the speed to about 900 rpm; (4) control the pulp (Cu-Mo concentrate) level to be just below the target (not to overflow before the air) and mix the slurry; (5) check the pulp pH and ORP (Oxidation-Reduction Potential) prior to the addition of chemicals (control NaSH or exemplary biopolymer-modified polycarbamides); (6) slowly add chemicals to the flotation cell (e.g., control NaSH or exemplary biopolymer-modified polycarbamide: ~ 550 mV ORP for full Cu depression); (7) add diesel as Mo collector if needed; (8) start and adjust air to the target flow rate (2 L / min or as needed); (9) float concentration 1 (first scrape of float bubbles) for 2 min in a collection pan (concentration 1) and measure the weight of the concentration 1 before the vacuum dry (mass pull 1); (10) record pH and ORP; (11) replace the collection pan and float concentration 2 for 3 min in a collection pan (concentration 2) and measure the weight of the concentration 2 before the vacuum dry (mass pull 2); and (12) record pH and ORP.

[0101] The XRF (X-Ray Fluorescence) measurement was conducted according to the following procedure: (1) vacuum-dry concentration 1 (float concentration 1) and concentration 2 (float concentration 2), as well as the tailing (depressed mineral), and determine the mass of each material (z.e., the total mineral concentrate is the sum of vacuum-dried concentration 1, vacuum-dried concentration 2, and vacuum-dried tailing); (2) oven-dry the materials overnight at 125°C, and determine the mass of each material; (3) measure and analyze the minerals from each material, and select Cu, Mo, Fe amounts on the XRF device; and (4) analyze Cu, Mo, Fe concentrations and obtain the recovery and grade of these minerals.

[0102] The results of the lab-scale flotation cell tests are summarized in Table 10.Table 10: Flotation Cell Test Results

[0103] As detailed in Table 10, the biopolymer-modified poly carbamide compositions described herein provided similar recovery of Cu and Mo as the control NaSH, and reduced or replaced NaSH at much lower chemical treatment levels. For example, the biopolymer- modified polycarbamide composition (Candidate 5 in Table 10) demonstrated sufficient Mo recovery and comparable Cu recovery data as the control NaSH at 43% total reduced chemical treatment level than the control NaSH (3.4 kg / T of Composition C-2 vs. 6 kg / T NaSH) and was able to significantly reduce the amount of NaSH.Example 5- Hydrophilic Polymer-Modified PolycarbamideExample 5(a)

[0104] An exemplary separation aid is prepared by synthesizing hydrophilic polymer- modified polycarbamide using a three-stage polymer process. The first stage forms a poly carbamide (including step 1), the second stage forms a hydrophilic polymer and modifies the polycarbamide therewith (including step 2), and the third stage includes modification with a sulfur compound, as a performance enhancing supplement (including steps 3 and 4).

[0105] In step 1, formaldehyde is charged into a reactor and the pH is adjusted to 7.0-9.0, preferably 7.5-8.5. Aqueous formaldehyde (53% concentration) is used for the polymer synthesis. Alternatively, urea-formaldehyde concentrate (UFC) may be used for the polymer synthesis. An exemplary UFC is composed of 60 wt.% formaldehyde, 25 wt.% urea, and 15 wt.% water. The pH adjusters include triethanolamine (TEA) and 50% NaOH, as well as optionally 6% sulfuric acid, or 10% formic acid, as needed. Additionally, N- methylolacrylamide (nMA) is added to the reactor. The levels of nMA may range from 0.1%- 30% (preferably around 0.5%-20%). Thereafter, a first urea charge (Ui) is added to the reactor, and the temperature is increased to 750°C-95°C, preferably 80°C-85°C. The batch is held at this temperature for 10-80 minutes, preferably for 15-25 minutes. The F / Ui \i.e.,formaldehyde:urea] mole ratio is from 1.5-4.0, preferably from 2.0-3.5. The urea and formaldehyde are reacted near neutral, at a pH range of 7.0-9.0, preferably 7.5-8.5, to form various (hydroxymethyl)urea intermediates (z.e., UF methylolation).

[0106] In step 2, the temperature is reduced to 55°C-90°C, preferably to 60°C-75°C, and ammonium persulfate (APS) is slowly added to the batch as an initiator for a radical polymerization of the nMA. Radical polymerization initiators may include any radical initiators, such as peroxide-based or azo compounds. The level of initiator, on a solids basis, is 0.001 wt.%-2 wt.%, preferably 0.01 wt.%-0.5 wt.% in the 100% liquid batch solution. After the completion of the APS charge, the pH is decreased to an acidic range of 3.0-6.0, preferably 3.8-4.3. The pH adjusters include acidic pH adjusters, such as 6% sulfuric acid, formic acid, and / or TEA, as needed. The second step is ended at a target Gardner-Holdt (G-H) bubble viscosity of D-X, preferably K-V, or “TU” by increasing the pH to about 7.0-9.0, preferably to 7.5-8.5, using TEA and 50% NaOH as the pH adjusters. A different degree of the polymerization can be achieved utilizing a different target end viscosity along with different F / Ui mole ratios and a different manufacturing pH range. The hydrophilic polymer (N- methylolacrylamide polymer) is formed via the radical polymerization during this step. The polycarbamide is also formed by reacting urea and formaldehyde in this step. A water charge is employed in this step to adjust the solids content and the viscosity of the batch.

[0107] In step 3, the temperature of the batch is lowered to 50°C-75°C, preferably 55°C- 70°C and 53% formaldehyde is charged into the reactor. The pH is adjusted to 7.5-8.0 with a pH adjuster, such as NaOH. One or more sulfur compounds are then added as performance enhancing supplements for improved Cu depression (or potentially other minerals as well). In this example, the performance enhancing supplement is thiourea (T). The batch is held for 10- 60 minutes, preferably for 20-40 minutes, and the batch pH is adjusted to 7.0-9.0, preferably to 7.5-8.5, using TEA (triethanolamine) and 50% NaOH with or without 6% sulfuric acidand / or 10% formic acid. During this step, thiourea reacts with residual formaldehyde and forms a thiourea-formaldehyde polymer. The level of thiourea can be varied in the range from about 0.1 wt.%-40 wt.%, preferably from 0.5 wt.%-30 wt.%. The mole ratio of F / (Ui+ T) can range from about 1-3.5 (preferably varying from about 1.5-3). Optionally, if not enough free formaldehyde is present in the polymer system, 53% formaldehyde (Fi) may be charged into the batch and the pH is adjusted to 7.0-9.0. The mole ratio of (F + Fi) / (Ui + T) was around 1.0 - 3.5. The levels of thiourea were around 0.1% - 40%.

[0108] In step 4, the reaction mixture is cooled to about 50°C-70°C, preferably 55°C-65°C, and a second urea (U2) is added to the reactor. The reaction mixture temperature is then further reduced to a temperature of 40°C-60°C, preferably 45°C-55°C and held for 5-60 minutes, preferably 15-45 minutes. The pH is adjusted to 7-9.5, preferably 7.5-9.0, using TEA and 6% sulfuric acid and / or 10% formic acid. The final (total F) / (UI+T+U2), mole ratio is from 0.5- 2.5, preferably 0.8-2.0. The process for preparing the hydrophilic polymer-modified polycarbamide is completed by cooling the batch to 20°C-26°C.Example 5(b)

[0109] An exemplary separation aid is prepared by synthesizing hydrophilic polymer- modified polycarbamide using a three-stage polymer process. The first stage forms a poly carbamide (including step 1), the second stage forms a hydrophilic polymer and modifies the polycarbamide therewith (including step 2), and the third stage includes modification with a sulfur compound, as a performance enhancing supplement (including steps 3 and 4).

[0110] In step 1, formaldehyde is charged into a reactor and the pH is adjusted to 7.0-9.0, preferably 7.5-8.5. Aqueous formaldehyde (53% concentration) is used for the polymer synthesis. Alternatively, urea-formaldehyde concentrate (UFC) may be used for the polymer synthesis. The pH adjusters include triethanolamine (TEA) and 50% NaOH, as well as optionally 6% sulfuric acid, or 10% formic acid, as needed. N-methylolacrylamide (nMA) isthen added to the reactor. The levels of nMA may range from 0.1%-30% (preferably around 0.5%-20%). Thereafter, a first urea charge (Ui) is added to the reactor, and the temperature is increased to 90°C-102°C, preferably 95°C-100°C. The batch is held at this temperature for 10- 80 minutes, preferably for 15-25 minutes. The F / Ui [i.e., formaldehyde:urea] mole ratio is from 1.5-4.0, preferably from 2.0-3.5. The urea and formaldehyde are reacted near neutral, at a pH range of 7.0-9.0, preferably 7.5-8.5, to form various (hydroxymethyl)urea intermediates (i.e., UF methylolation).

[0111] In step 2, the temperature is reduced to 55°C-90°C, preferably to 60°C-75°C, and ammonium persulfate (APS) is slowly added to the batch as an initiator for a radical polymerization of the nMA. The level of initiator, on a solids basis, is 0.001 wt.%-2 wt.%, preferably 0.01 wt.%-0.5 wt.% in the 100% liquid batch solution. After the completion of the APS charge, the pH is decreased to an acidic range of 3.0-6.0, preferably 3.5-5.5. The pH adjusters include acidic pH adjusters, such as 6% sulfuric acid, formic acid, and / or TEA, as needed. The second step is ended at a target Gardner-Holdt (G-H) bubble viscosity of D-X, preferably K-V. or “T”, by increasing the pH to about 7.0-9.0, preferably to 7.5-8.5, using TEA and 50% NaOH as the pH adjusters. A different degree of the polymerization can be achieved utilizing a different target end viscosity along with different F / Ui mole ratios and a different manufacturing pH range. The hydrophilic polymer (N-methylolacrylamide polymer) is formed via the radical polymerization during this step. The polycarbamide is also formed by reacting urea and formaldehyde in this step. A water charge is employed in this step to adjust the solids content and the viscosity of the batch.

[0112] In step 3, the temperature of the batch is lowered to 50°C-75°C, preferably 55°C- 70°C and one or more sulfur compounds may be added as performance enhancing supplements for improved Cu depression (or potentially other minerals as well). In this example, the performance enhancing supplement is thiourea (T). The batch is held for 10-60 minutes,preferably for 20-40 minutes, and the batch pH is adjusted to 7.0-9.0, preferably to 7.5-8.5, using TEA (triethanolamine) and 50% NaOH with or without 6% sulfuric acid and / or 10% formic acid. During this step, thiourea reacts with residual formaldehyde and forms a thioureaformaldehyde polymer. The level of thiourea can be varied in the range from about 0.1 wt.%- 40 wt.%, preferably from 0.5 wt.%-30 wt.%. The mole ratio of F / (Ui+ T) can range from about 1-3.5 (preferably varying from about 1.5-3). Optionally, if not enough free formaldehyde is present in the polymer system, 53% formaldehyde (Fi) may be charged into the batch and the pH is adjusted to 7.0-9.0. The mole ratio of (F + Fi) / (Ui + T) was around 1.0 - 3.5. The levels of thiourea were around 0.1% - 40%.

[0113] In step 4, the reaction mixture is cooled to about 50°C-70°C, preferably 55°C-65°C, and a second urea (U2) is added to the reactor. The reaction mixture temperature is then further reduced to a temperature of 40°C-60°C, preferably 45°C-55°C and held for 5-60 minutes, preferably 15-45 minutes. The pH is adjusted to 7-9.5, preferably 7.5-9.0, using TEA and 6% sulfuric acid and / or 10% formic acid. The final (total F) / (UI+T+U2), mole ratio is from 0.5- 2.5, preferably 0.8-2.0. The process for preparing the hydrophilic polymer-modified polycarbamide is completed by cooling the batch to 20°C-26°C.

[0114] A summary of the synthesis processes of Examples 5(a) and 5(b)is provided below in Table 11.Table 11 : Synthesis of Exemplary Hydrophilic Polymer-Modified Polycarbamides

[0115] The chemical preparation of the exemplary hydrophilic polymer-modified polycarbamide separation aids, Compounds C-3 and C-4, is shown in Table 12.Table 12: Chemical Preparation of Exemplary Hydrophilic Polymer-Modified Poly carbamide Separation Aids (wt.%)1: 53% concentration aqueous formaldehyde; 2: Triethanolamine; 3: N-methylolacrylamide; 4: ammonium persulfate.

[0116] The hydrophilic polymer-modified polycarbamide separation aids were thereafter examined for pH, solids, viscosity, color, and stability at both 4°C and 20°C-26°C (room temperature) storage, as summarized in Table 3. Viscosity was measured in accordance withASTM D2983-03 using a Brookfield viscometer. Polymer stability was determined by the lack of phase separation or precipitation formation over time at 4°C and 20°C-26°C by visual observation. The exemplary hydrophilic polymer-modified polycarbamide separation aids demonstrated very good storage stability at 20°C-26°C, as well as 4°C storage stability, without any phase separation or precipitation.Table 13: Characteristics of Exemplary Hydrophilic Polymer-Modified Polycarbamide Separation Aids1: Room Temperature (20°C-26°C)Example 6- Flotation Tests

[0117] Lab-scale flotation tests were conducted using the hydrophilic polymer-modified poly carbamides, Compounds C-3 and C-4, as described in Example 5. The tests were conducted using a Metso D-12V flotation machine (manufactured by Metso Minerals Industries, Inc.). The minerals (Cu, Mo) from the floated concentrates as well as the tailing were measured by XRF (X-Ray Fluorescence) analyzer (manufactured by Thermo Scientific Niton XL3t GOLDD+). The Cu-Mo bulk concentrate was obtained from a copper mine in Arizona in the United States. The Cu-Mo concentrate contained typical industry levels of Cu and Mo, which are around 20% to 30% copper and 0.2% to 1.0% molybdenum. The hydrophilic polymer-modified polycarbamides were employed with or without supplemental depressants for the flotation tests. When the hydrophilic polymer-modified polycarbamide was employed with supplemental depressants for the flotation study, the hydrophilic polymer- modified polycarbamide and the supplemental depressants may be added separately, or they may be pre-mixed prior to the test and added as a one-part system.

[0118] The lab-scale flotation cell test was conducted according to the following procedure: (1) thaw 500 g of ore sample (Cu-Mo concentrate) in a warm water bath; (2)transfer the Cu-Mo bulk concentrate to a flotation cell; (3) start the impeller and adjust the speed to about 900 rpm; (4) control the pulp (Cu-Mo concentrate) level to be just below the target (not to overflow before the air) and mix the slurry; (5) check the pulp pH and ORP (Oxidation-Reduction Potential) prior to the addition of chemicals (control NaSH or exemplary hydrophilic polymer-modified polycarbamide); (6) slowly add chemicals to the flotation cell (e.g., control NaSH or exemplary hydrophilic polymer-modified polycarbamide: ~ 550 mV ORP for full Cu depression); (7) add diesel as Mo collector if needed; (8) start and adjust air to the target flow rate (2 L / min or as needed); (9) float concentration 1 (first scrape of float bubbles) for 2 min in a collection pan (concentration 1) and determine the mass of the concentration 1 before the vacuum dry (mass pull 1); (10) record pH and ORP; (11) replace the collection pan and float concentration 2 for 3 min in a collection pan (concentration 2) and determine the mass of the concentration 2 before the vacuum dry (mass pull 2); and (12) record pH and ORP.

[0119] The XRF (X-Ray Fluorescence) measurement was conducted according to the following procedure: (1) vacuum-dry concentration 1 (float concentration 1) and concentration 2 (float concentration 2), as well as the tailing (depressed mineral), and determine the mass of each material (z.e., the total mineral concentrate is the sum of vacuum-dried concentration 1, vacuum-dried concentration 2, and vacuum-dried tailing); (2) oven-dry the materials overnight at 125°C, and determine the mass of each material; (3) measure and analyze the minerals from each material, and select Cu, Mo, Fe amounts on the XRF device; and (4) analyze Cu, Mo, Fe concentrations and obtain the recovery and grade of these minerals.

[0120] The results of the lab-scale flotation cell tests are summarized in Tables 14-16. Depressants comprising a mixture of Comp. C-3 and C-4 and supplemental depressants are noted below.Table 14: Flotation Cell Test Results (Study #1)1 = 5kg / T Comp. C-3 + Ikg / T S-TGATable 15: Flotation Cell Test Results (Study #2)2 = 2kg / T Comp. C-3+ 0.5kg / T S-TGATable 16: Flotation Cell Test Results (Study #3)

[0121] As detailed in Tables 14-16, the hydrophilic polymer-modified poly carbamide compositions described herein, with and without supplemental depressants, provided similar recovery of Cu and Mo as the control NaSH, and reduced or replaced NaSH at much lower chemical treatment levels. For example, the hydrophilic polymer modified polycarbamide composition with performance enhancing supplement (Candidate 9 in Table 15 and Candidate 10 in Table 16) exhibited equal or comparable Cu depression as the control NaSH at lower chemical treatment levels than the control NaSH and was able to replace 100% NaSH.Alkylated PolycarbamideExample 7- Preparation of Alkylated Polycarbamide Separation Aids

[0122] Exemplary separation aids are prepared by synthesizing alkylated polycarbamide using a three-stage polymer process. A first stage includes the methylation of (hydroxymethyl)urea (including step 1), a second stage forms the poly carbamide (including step 2), and a third stage modifies the alkylated polycarbamide with sulfur as a performanceenhancing supplement (including steps 3 and 4).

[0123] In the first stage, formaldehyde is charged into a reactor and the pH is adjusted to 7.0-9.0, preferably 7.5-8.5. Aqueous formaldehyde (53% concentration) is used for the polymer synthesis. Alternatively, urea-formaldehyde concentrate (UFC) may be used for the polymer synthesis. An exemplary UFC is composed of 60 wt.% formaldehyde, 25 wt.% urea, and 15 wt.% water. The pH adjusters include triethanolamine (TEA) and 50% NaOH, as well as optionally 6% sulfuric acid, or 10% formic acid, as needed. A methylating agent, such as methanol, is then charged to the batch in an amount (methanol to polycarbamide (wt. / wt.) between 0.1 wt.%-30 wt.%, preferably 0.5 wt.%-20 wt.%. Thereafter, a first urea charge (Ui) is added to the reactor, and the temperature is increased to 90°C-102°C, preferably 95°C- 100°C. The batch is held at this temperature for 10-80 minutes, preferably for 15-50 minutes. The F / Ui [i.e., formaldehyde:urea] mole ratio is from 1.5-4.0, preferably from 2.0-3.5. The urea and formaldehyde are reacted near neutral, at a pH range of 7.0-9.0, preferably 7.5-8.5, to form various (hydroxymethyl)urea intermediates (i.e., UF methylolation). During this step, the methylation of (hydroxymethyl)urea occurs from reacting (hydroxymethyl)urea and methanol.

[0124] The second stage includes the formation of a polycarbamide by reacting methylated (hydroxymethyl)urea and formaldehyde in step 2, thereby forming a methylated polycarbamide separation aid.

[0125] In step 2, the pH is decreased to an acidic range of 3.0 - 6.0, preferably to 4.0 - 5.0. The pH adjusters include acidic pH adjusters, such as 6% sulfuric acid, formic acid, and / or TEA, as needed. The temperature is held at 90°C-102°C, preferably 95°C-100°C duringpoly carbamide formation, preferably for about 15-25 minutes. The second step is ended at a target Gardner-Holdt (G-H) bubble viscosity of “D - UV,” preferably “K - P” by increasing the pH to about 7.0 - 9.0, preferably to 7.5 - 8.5, using TEA and 50%NaOH as the pH adjusters. A different degree of the polymerization can be achieved utilizing a different target end viscosity along with different F / Ui mole ratios and a different manufacturing pH range. After reaching the target viscosity, vacuum distillation is applied to remove free methanol and adjust the solids content of the batch. The temperature is adjusted to 50°C-80°C, preferably 55°C- 70°C.

[0126] The third stage modifies the methylated polycarbamide with performance enhancing supplements.

[0127] In step 3, sodium metabisulfite was added to the batch in an amount of 0.1 wt.% - 30 wt.%, preferably about 0.2 wt.% - 10 wt.% and mixed for 5 - 60 minutes, preferably for 15- 40 minutes, at 55°C - 75°C, preferably to 60°C - 70°C. The batch pH at this step was 7.0 - 9.0, preferably to 7.5 - 8.5. Different types of performance enhancing supplements other than sodium metabisulfite can be used, such as (but not limited to) sodium bisulfite, sodium sulfite, sodium thiosulfate, thiourea-formaldehyde polymer, etc.

[0128] When thiourea-formaldehyde polymer is used as a performance enhancing supplement at this step, thiourea (T) is charged into the batch and the pH is adjusted to 7.0 - 9.0 (preferably to 7.5 - 8.5) using TEA (triethanolamine) and 50% NaOH with or without 6% sulfuric acid. The batch is maintained at 50°C - 75°C, preferably to 55°C - 70°C, for 10 - 60 minutes (preferably for 20 - 50 minutes). Thiourea-formaldehyde polymer is formed from the reaction between thiourea and residual free formaldehyde. Optionally, if there is an insufficient amount of free formaldehyde is present in the polymer system, 53% formaldehyde (Fi) may be charged into the batch. The pH is adjusted to 7.0 - 9.0 and maintained at a temperature of 50°C- 75°C for 10 - 60 minutes. The mole ratio of (F + Fi) / (Ui + T) is around 1.0 - 3.5, preferablyabout 1.5 - 3.0. The levels of thiourea added to the batch are 0.1 wt.% - 40 wt.%, preferably about 0.5 wt.% - 30 wt.%.

[0129] In step 4, the reaction mixture is cooled to about 50°C-70°C, preferably to 55°C- 65°C, and a second urea charge (U2) is added to the reactor. The batch temperature is held at 40°C-60°C, preferably at 45°C - 55°C, for 5 - 60 minutes, preferably for 15 - 45 minutes. The pH is adjusted to 7.0-9.5, preferably 7.5-9.0, using TEA and 6% sulfuric acid. The final F / (Ui + U2) mole ratio is from about 0.5-2.5, preferably from 0.8-2.0. The process for manufacturing the methylated polycarbamide is completed by cooling the batch to 20°C-26°C.

[0130] A summary of the synthesis process of Example 7 is provided below in Table 17.Table 17: Synthesis of Exemplary Methylated Polycarbamide Separation Aid

[0131] The formulation of the exemplary methylated polycarbamide separation aid,Compound D-l, is shown in Table 18.Table 18: Chemical Preparation of Exemplary Methylated Polycarbamide Separation Aid (wt.%)1: 53% concentration aqueous formaldehyde; 2: Triethanolamine; 3: 6%> sulfuric acid; 4: vacuum distillation; 5: sodium metabisulfite.

[0132] The methylated polycarbamide separation aid was examined for pH, solids, viscosity, color, and stability at both 4°C and 20°C-26°C storage, as summarized in Table 19. Viscosity was measured in accordance with ASTM D2983-03 using a Brookfield viscometer. Polymer stability was determined by the lack of phase separation or precipitation formation over time at 4°C and 20°C-26°C (room temperature) by visual observation. The exemplary methylated polycarbamide separation aid demonstrated very good storage stability at 20°C- 26°C, as well as 4°C storage stability, without any phase separation or precipitation.Table 19: Characteristics of Exemplary Methylated Polycarbamide Separation Aid1: room temperature (20°C-26°C).Example 8- Flotation Tests

[0133] Lab-scale flotation tests were conducted using the methylated polycarbamide of Compound D-l, as described in Example 7. The tests were conducted using a Metso D-12V flotation machine (manufactured by Metso Minerals Industries, Inc.). The minerals (Cu, Mo) from the floated concentrates as well as the tailing were measured by XRF (X-Ray Fluorescence) analyzer (manufactured by Thermo Scientific Niton XL3t GOLDD+). The Cu- Mo bulk concentrate was obtained from a copper mine in Arizona in the United States. TheCu-Mo concentrate contained typical industry levels of Cu and Mo, which are around 20% to 30% copper and 0.2% to 1.0% molybdenum. The methylated polycarbamide was employed with a low level of NaSH as a supplemental depressant for the flotation tests. The methylated polycarbamide and the supplemental depressants may be added separately, or they may be premixed prior to the test and added as a one-part system.

[0134] The lab-scale flotation cell test was conducted according to the following procedure: (1) thaw 500 g of ore sample (Cu-Mo concentrate) in a warm water bath; (2) transfer the Cu-Mo bulk concentrate to a flotation cell; (3) start the impeller and adjust the speed to about 900 rpm; (4) control the pulp (Cu-Mo concentrate) level to be just below the target (not to overflow before the air) and mix the slurry; (5) check the pulp pH and ORP (Oxidation-Reduction Potential) prior to the addition of chemicals (control NaSH or exemplary methylated polycarbamide); (6) slowly add chemicals to the flotation cell (e.g., control NaSH: ~ 550 mV ORP for full Cu depression); (7) add diesel as Mo collector if needed; (8) start and adjust air to the target flow rate (2 L / min or as needed); (9) float concentration 1 (first scrape of float bubbles) for 2 min in a collection pan (concentration 1) and determine the mass of the concentration 1 before the vacuum dry (mass pull 1); (10) record pH and ORP; (11) replace the collection pan and float concentration 2 for 3 min in a collection pan (concentration 2) and determine the mass of the concentration 2 before the vacuum dry (mass pull 2); and (12) record pH and ORP.

[0135] The XRF (X-Ray Fluorescence) measurement was conducted according to the following procedure: (1) vacuum-dry concentration 1 (float concentration 1) and concentration 2 (float concentration 2), as well as the tailing (depressed mineral), and determine the mass of each material (z.e., the total mineral concentrate is the sum of vacuum-dried concentration 1, vacuum-dried concentration 2, and vacuum-dried tailing); (2) oven-dry the materials overnight at 125°C, and determine the mass of each material; (3) measure and analyze the minerals fromeach material, and select Cu, Mo, Fe amounts on the XRF device; and (4) analyze Cu, Mo, Fe concentrations and obtain the recovery and grade of these minerals.

[0136] The results of the lab-scale flotation cell tests are summarized in Table 20.Table 20: Flotation Cell Test Results

[0137] As detailed in Table 20, the methylated polycarbamide compositions described herein provided similar recovery of Cu and Mo as the control NaSH, and significantly reduced the use of NaSH, while lowering the overall chemical treatment level. For example, the methylated polycarbamide composition (Candidate 11) demonstrated good Cu-Mo recovery data at 60% total reduced chemical treatment level than the control NaSH.Example 9- Preparation of Biopolymer-Modified Alkylated Polycarbamide Separation Aids

[0138] Exemplary separation aids are prepared by synthesizing biopolymer-modified alkylated polycarbamide using a three-stage polymer process. The alkylating agent in this example is a methylating agent (e.g., methanol) and therefore the synthesis process produces a biopolymer polymer-modified methylated polycarbamide. A first stage includes the methylation of (hydroxymethyl)urea (including step 1), a second stage forms the methylated polycarbamide (including step 2), and a third stage modifies the methylated polycarbamide with a biopolymer (including steps 3 and 4).

[0139] In the first stage, formaldehyde is charged into a reactor and the pH is adjusted to7.0-9.0, preferably 7.5-8.5. Aqueous formaldehyde (53% concentration) is used for the polymer synthesis. Alternatively, urea-formaldehyde concentrate (UFC) may be used for thepolymer synthesis. An exemplary UFC is composed of 60 wt.% formaldehyde, 25 wt.% urea, and 15 wt.% water. The pH adjusters include triethanolamine (TEA) and 50% NaOH, as well as optionally 6% sulfuric acid, or 10% formic acid, as needed. A methylating agent, such as methanol, is then charged to the batch in an amount (methanol to polycarbamide (wt. / wt.) between 0.1 wt.%-30 wt.%, preferably 0.5 wt.%-20 wt.%. Thereafter, a first urea charge (Ui) is added to the reactor, and the temperature is increased to 90°C-107°C, preferably 95°C- 102°C. The batch is held at this temperature for 10-80 minutes, preferably for 15-50 minutes. The F / Ui [i.e., formaldehyde:urea] mole ratio is from 1.5-4.0, preferably from 2.0-3.5. The urea and formaldehyde are reacted near neutral, at a pH range of 7.0-9.0, preferably 7.5-8.5, to form various (hydroxymethyl)urea intermediates (i.e., UF methylolation). During this step, the methylation of (hydroxymethyl)urea occurs from reacting (hydroxymethyl)urea and methanol.

[0140] The second stage includes the formation of a polycarbamide by reacting methylated (hydroxymethyl)urea and formaldehyde in step 2, thereby forming a methylated polycarbamide separation aid.

[0141] In step 2, the pH is decreased to an acidic range of 3.0 - 6.0, preferably to 3.5 - 5.5. The pH adjusters include acidic pH adjusters, such as 6% sulfuric acid, formic acid, and / or TEA, as needed. The temperature is held at 90°C-102°C, preferably 95°C-100°C during poly carbamide formation, preferably for about 15-25 minutes. The second step is ended at a target Gardner-Holdt (G-H) bubble viscosity of “D - UV,” preferably “K - P” by increasing the pH to about 7.0 - 9.0, preferably to 7.5 - 8.5, using TEA and 50% NaOH as the pH adjusters. A different degree of the polymerization can be achieved utilizing a different target end viscosity along with different F / Ui mole ratios and a different reaction pH range. After reaching the target viscosity, vacuum distillation is applied to remove free methanol and adjust the solids content of the batch. The temperature is then adjusted to 50°C-80°C, preferably 55°C-70°C.

[0142] The third stage includes the addition of a biopolymer (e.g., starch) to the methylated polycarbamide in steps 3 and 4, thereby forming a biopolymer-modified methylated polycarbamide separation aid.

[0143] In step 3, the temperature of the methylated polycarbamide product is adjusted to about 70°C-95°C, preferably to 75°C-90°C, and a premixture of starch and water is added to the reactor. At this step, starch is dispersed first in the methylated polycarbamide solution and de-natured (or disentangled), which causes the starch to swell. The batch temperature is held for 5-60 minutes, preferably 15-50 minutes, and the polymer viscosity increases over time. The starch level ranges from 0.01 wt.%-10 wt.%, preferably from 0.1 wt.%-4 wt.%. The pH at this step is 7.0-9.0, preferably 7.5-8.5. After reaching the target viscosity (such as a target Gardner- Holdt (G-H) bubble viscosity of “E-X”), vacuum cooling or cooling water was applied to lower the temperature of the batch to 60°C-65°C. A water charge is employed at this step to adjust the solids content and the viscosity of the batch to the desired range.

[0144] In the fourth step, the reaction mixture was cooled to about 50°C-70°C, preferably 55°C-65°C, and the second urea (U2) is added to the reactor. The batch temperature is then further reduced to a temperature of 40°C-60°C, preferably 45°C-55°C and held for 5-60 minutes, preferably 15-45 minutes. The pH is adjusted to 7.0-9.5, preferably 7.5-9.0, using TEA and 6% sulfuric acid and / or 10% formic acid. The final (total F) / (total U), or F / (Ui + U2) mole ratio was from 0.5-2.5, preferably 0.8-2.0. The process for preparing the biopolymer- modified methylated polycarbamide was completed by cooling the batch to 20°C-26°C.

[0145] A summary of the synthesis process of Example 9 is provided below in Table 21.Table 21 : Synthesis of Exemplary Biopolymer-Modified Methylated Polycarbamide

[0146] The chemical formulation of the exemplary biopolymer-modified methylated polycarbamide separation aid, Compound D-2, is shown in Table 22.Table 22: Chemical Formulation of Exemplary Biopolymer-Modified Methylated Polycarbamide (wt.%)1: 53% concentration aqueous formaldehyde; 2: Triethanolamine; 3: 6% sulfuric acid; 4: vacuum distillation; 5: cationic starch powder (premixed with water before charge).

[0147] The biopolymer-modified methylated polycarbamide separation aid was thereafter examined for pH, solids, viscosity, color, and stability at both 4°C and 20°C-26°C storage, as summarized in Table 23. The exemplary biopolymer-modified methylated polycarbamideseparation aids demonstrated very good storage stability at 20°C-26°C (room temperature), as well as 4°C storage stability, without any phase separation or precipitation.Table 23: Characteristics of Exemplary Biopolymer-Modified Methylated Polycarbamide Separation Aid1: room temperature (20°C-26°C).Example 10

[0148] Lab-scale flotation tests were conducted using biopolymer-modified methylated polycarbamide, Compound D-2, as described in Example 8. The tests were conducted using a Metso D-12V flotation machine (manufactured by Metso Minerals Industries, Inc.). The minerals (Cu, Mo) from the floated concentrates as well as the tailing were measured by XRF (X-Ray Fluorescence) analyzer (manufactured by Thermo Scientific Niton XL3t GOLDD+). The Cu-Mo bulk concentrate was obtained from a copper mine in Arizona in the United States. The Cu-Mo concentrate contained typical industry levels of Cu and Mo, which are around 20% to 30% copper and 0.2% to 1.0% molybdenum. The biopolymer-modified methylated polycarbamides were employed with various supplemental depressants for the flotation tests. The biopolymer-modified methylated polycarbamides and the supplemental depressants may be added separately, or they may be pre-mixed prior to the test and added as a one-part system.

[0149] The lab-scale flotation cell test was conducted according to the following procedure: (1) thaw 500 g of ore sample (Cu-Mo concentrate) in a warm water bath; (2) transfer the Cu-Mo bulk concentrate to a flotation cell; (3) start the impeller and adjust the speed to about 900 rpm; (4) control the pulp (Cu-Mo concentrate) level to be just below the target (not to overflow before the air) and mix the slurry; (5) check the pulp pH and ORP (Oxidation-Reduction Potential) prior to the addition of chemicals (control NaSH or exemplary biopolymer-modified methylated polycarbamides); (6) slowly add chemicals to the flotation cell (e.g., control NaSH or exemplary biopolymer-modified alkylated polycarbamide: ~ 550mV ORP for full Cu depression); (7) add diesel as Mo collector if needed; (8) start and adjust air to the target flow rate (2 L / min or as needed); (9) float concentration 1 (first scrape of float bubbles) for 2 min in a collection pan (concentration 1) and measure the weight of the concentration 1 before the vacuum dry (mass pull 1); (10) record pH and ORP; (11) replace the collection pan and float concentration 2 for 3 min in a collection pan (concentration 2) and measure the weight of the concentration 2 before the vacuum dry (mass pull 2); and (12) record pH and ORP.

[0150] The XRF (X-Ray Fluorescence) measurement was conducted according to the following procedure: (1) vacuum-dry concentration 1 (float concentration 1) and concentration 2 (float concentration 2), as well as the tailing (depressed mineral), and determine the mass of each material (z.e., the total mineral concentrate is the sum of vacuum-dried concentration 1, vacuum-dried concentration 2, and vacuum-dried tailing); (2) oven-dry the materials overnight at 125°C, and determine the mass of each material; (3) measure and analyze the minerals from each material, and select Cu, Mo, Fe amounts on the XRF device; and (4) analyze Cu, Mo, Fe concentrations and obtain the recovery and grade of these minerals.

[0151] The results of the lab-scale flotation cell tests are summarized in Table 24.Table 24: Flotation Cell Test Results

[0152] As detailed in Table 24, the biopolymer-modified methylated polycarbamide compositions described herein provided similar recovery of Cu and Mo as the control NaSH, and reduced or replaced NaSH at much lower chemical treatment levels. For example, the biopolymer-modified methylated poly carbamide compositions (Candidates 12 and 13 in Table24, Comp. D-2) demonstrated sufficient and comparable Cu recovery data as the control NaSH (Control) at 60% total reduced chemical treatment level than the control NaSH (2kg / T Candidates 1 and 2 vs. 5kg / T NaSH in Control 1) and was able to replace 100% NaSH using 100% organic polymer.Example 11-Preparation of Hydrophilic Polymer-Modified Methylated Polycarbamide Separation AidsExample 11 (a)

[0153] An exemplary separation aid is prepared by synthesizing hydrophilic polymer- modified alkylated polycarbamide using a three-stage polymer process, including multiple steps, some of which occur simultaneously. The alkylating agent in this example is a methylating agent (e.g., methanol) and therefore the synthesis process produces a hydrophilic polymer-modified methylated polycarbamide. A first stage includes the methylation of (hydroxymethyl)urea, a second stage forms the methylated polycarbamide and hydrophilic polymer, and modifies the methylated polycarbamide therewith, and a fourth stage includes further modification with a performance-enhancing supplement.

[0154] In the first stage, formaldehyde is charged into a reactor and the pH is adjusted to 7.0-9.0, preferably 7.5-8.5. Aqueous formaldehyde (53% concentration) is used for the polymer synthesis. Alternatively, urea-formaldehyde concentrate (UFC) may be used for the polymer synthesis. An exemplary UFC is composed of 60 wt.% formaldehyde, 25 wt.% urea, and 15 wt.% water. The pH adjusters include triethanolamine (TEA) and 50% NaOH, as well as optionally 6% sulfuric acid, or 10% formic acid, as needed. A methylating agent, such as methanol, is then charged to the batch in an amount (methanol to polycarbamide (wt. / wt.)) between 0.1 wt.%-30 wt.%, preferably 0.5 wt.%-20 wt.%. Additionally, N-methylolacrylamide (nMA) is added to the reactor. The levels of nMA may range from 0.1% - 20% (preferably around 0.5%-10%). Thereafter, a first urea charge (Ui) is added to the reactor, and thetemperature is increased to 90°C-107°C, preferably 95°C-102°C. The batch is held at this temperature for 10-80 minutes, preferably for 30-70 minutes. The F / Ui [i.e., formaldehyde:urea] mole ratio is from 1.5-4.0, preferably from 2.0-3.5. The urea and formaldehyde are reacted near neutral, at a pH range of 7.0-9.0, preferably 7.5-8.5, to form various (hydroxymethyl)urea intermediates (i.e., UF methylolation). During this step, the methylation of (hydroxymethyl)urea occurs from reacting (hydroxymethyl)urea and methanol.

[0155] In the second stage, the temperature is reduced to 55°C-90°C, preferably to 60°C- 80°C. The batch is held at this temperature (60°C-80°C) and the pH is increased to about 7.0- 9.0, preferably to 7.5-8.5, using TEA and 50% NaOH until the batch reaches a target Gardner- Holdt (G-H) bubble viscosity of D - X, preferably K-V. The methylated polycarbamide forms by reacting the methylated (hydroxymethyl)urea and formaldehyde in this step.

[0156] Meanwhile, ammonium persulfate (APS) is slowly added to the reaction mixture as an initiator for a radical polymerization of the nMA. The radical polymerization initiator may include any radical initiator, such as a peroxide-based or azo compound. The level of initiator, on a solids basis, is 0.001 wt.%-2.0 wt.%, preferably 0.01 wt.%-0.5 wt.% in the 100% liquid batch solution. After the completion of the APS charge, the pH is decreased to an acidic range of 3.5-6.0, preferably 3.8-5.0. The pH adjusters include acidic pH adjusters, such as 6% sulfuric acid, formic acid, and / or TEA, as needed. The hydrophilic polymer (N-methylolacrylamide polymer) forms via radical polymerization under acidic conditions.

[0157] After reaching the target viscosity discussed above, a water charge is employed to adjust the solids content and the viscosity of the batch. The levels of nMA may range from 0.1 wt.% - 20 wt.% (preferably around 0.5 wt.% - 10 wt.%) in the liquid batch solution.

[0158] In a third stage, the temperature of the batch is lowered to about 50°C-75°C, preferably about 55°C-70°C and one or more sulfur compounds are added as performance enhancing supplements for improved Cu depression (or potentially other minerals as well). Inone example, the performance enhancing supplement is thiourea (T). The batch is held for 10- 60 minutes, preferably for 20-40 minutes, and the batch pH is adjusted to 7.0-9.0, preferably to 7.5-8.5, using TEA (triethanolamine) and 50% NaOH with or without 6% sulfuric acid and / or 10% formic acid. During this step, thiourea reacts with residual formaldehyde and forms a thiourea-formaldehyde polymer.. The level of thiourea can be varied in the range from about 0.1 wt.% - 40 wt.%, preferably from 0.5 wt.% - 30 wt.%. The mole ratio of F / (Ui+ T) can range from about 1 - 3.5 (preferably varying from about 1.5 - 3).

[0159] The reaction mixture is then cooled to 50°C-70°C, preferably 55°C-65°C, and a second urea (U2) is added to the reactor. The batch temperature is held at 40°C-60°C, preferably 45°C-55°C for 5-60 minutes, preferably 15-45 minutes. The pH is adjusted to 7- 9.5, preferably 7.5-9.0, using TEA and 6% sulfuric acid and / or 10% formic acid. The final (total F) / (UI+T+U2), mole ratio is from 0.5-2.5, preferably 0.8-2.0. The process for manufacturing the hydrophilic polymer-modified methylated polycarbamide is completed by cooling the batch to 20°C-26°C.

[0160] A summary of the synthesis process of Example 11(a) is provided below in Table24.Table 24: Synthesis of Exemplary Hydrophilic Polymer-Modified Methylated PolycarbamidesExample 11 (b)

[0161] An exemplary separation aid is prepared by synthesizing hydrophilic polymer- modified alkylated polycarbamide including a performance enhancing supplement and biopolymers, using a four-stage polymer process. As with Example 11(a), the alkylating agent in the subject example is a methylating agent (e.g., methanol). A first stage includes the methylation of (hydroxymethyl)urea, a second stage forms the methylated polycarbamide and hydrophilic polymer, and modifies the methylated polycarbamide therewith, a third stage includes further modification with a performance-enhancing supplement, and a fourth stage includes further modification with biopolymer.

[0162] Stages 1-3 occur as detailed in Example 11(a).

[0163] As mentioned above, stage 4 further modifies the hydrophilic polymer-modified methylated polycarbamide with one or more biopolymers.

[0164] In stage 4, the reaction mixture is cooled to about 30°C - 50°C, preferably to 35°C - 45°C, and a liquid cationic starch (30% aqueous solution) biopolymer is added to the reactor. The batch temperature is held at 30°C - 50°C, preferably at 35°C - 45°C, for 5 - 60 minutes, preferably for 15 - 45 minutes. The pH is adjusted to 7.0 - 9.5, preferably to 7.5 - 9.0, using TEA and 6% sulfuric acid. The level of the liquid cationic starch can be varied from around 0.1 wt.% - 30 wt.%, preferably from around 0.5 wt.% - 15 wt.%, based on the total weight of the reaction mixture. Alternatively, a liquid carboxylated methyl cellulose (CMC, 5% aqueoussolution) may be added to the reactor in place of the liquid starch addition. The level of the liquid CMC solution can be varied from around 0.1 wt.% - 30 wt.% (preferably from around 0.5 wt.% - 15 wt.%), based on the total weight of the reaction mixture.

[0165] The manufacturing process for the hydrophilic polymer modified and methylated polycarbamide with performance-enhancing supplements and biopolymers is completed by cooling the batch to 22°C - 26°C.

[0166] A summary of the synthesis process of Example 11(b) is provided below in Table 25.Table 25 : Synthesis of Exemplary Hydrophilic Polymer-Modified Methylated Polycarbamides with Biopolymer

[0167] The chemical preparation of the exemplary methylated polycarbamide separation aids, Compounds D-3, D-4, D-5, and D-6 are shown in Table 26.Table 26: Chemical Preparation of Exemplary Hydrophilic Polymer-Modified Methylated Polycarbamide (wt.%)1: 53% concentration aqueous formaldehyde; 2: Triethanolamine; 3: N -methylolacrylamide;; 4: ammonium persulfate; 5: 5% concentration aqueous CMC (carboxy methylcellulose) solution; 6: 30% concentration aqueous cationic starch solution.

[0168] The hydrophilic polymer-modified methylated polycarbamide separation aids were thereafter examined for pH, solids, viscosity, color, and stability at both 4°C and 20°C-26°C storage, as summarized in Table 27. Viscosity was measured in accordance with ASTM D2983-03 using a Brookfield viscometer. Polymer stability was determined by the lack of phase separation or precipitation formation over time at 4°C and 20°C-26°C (room temperature) by visual observation. The exemplary hydrophilic polymer-modified methylated polycarbamide separation aids demonstrated very good storage stability at 20°C-26°C (room temperature), as well as 4°C storage stability, without any phase separation or precipitation.Table 27: Characteristics of Exemplary Hydrophilic Polymer-Modified Methylated Polycarbamide Separation Aids1: Room Temperature (20°C-26°C)Example 12

[0169] Lab-scale flotation tests were conducted using the hydrophilic polymer-modified methylated poly carbamides, Compounds D-3. D-4. D-5, and D-6, as described in Example 11. The tests were conducted using a Metso D-12V flotation machine (manufactured by Metso Minerals Industries, Inc.). The minerals (Cu, Mo) from the floated concentrates as well as the tailing were measured by XRF (X-Ray Fluorescence) analyzer (manufactured by Thermo Scientific Niton XL3t GOLDD+). The Cu-Mo bulk concentrate was obtained from a copper mine in Arizona in the United States. The Cu-Mo concentrate contained typical industry levels of Cu and Mo, which are around 20% to 30% copper and 0.2% to 1.0% molybdenum. The hydrophilic polymer-modified methylated polycarbamides were employed with or without supplemental depressants for the flotation tests. When the hydrophilic polymer-modified methylated polycarbamide was employed with supplemental depressants for the flotation study, the hydrophilic polymer-modified methylated poly carbamide and the supplemental depressants may be added separately, or they may be pre-mixed prior to the test and added as a one-part system.

[0170] The lab-scale flotation cell test was conducted according to the following procedure: (1) thaw 500 g of ore sample (Cu-Mo concentrate) in a warm water bath; (2) transfer the Cu-Mo bulk concentrate to a flotation cell; (3) start the impeller and adjust the speed to about 900 rpm; (4) control the pulp (Cu-Mo concentrate) level to be just below the target (not to overflow before the air) and mix the slurry; (5) check the pulp pH and ORP(Oxidation-Reduction Potential) prior to the addition of chemicals (control NaSH or exemplary hydrophilic polymer-modified methylated polycarbamide); (6) slowly add chemicals to the flotation cell (e.g., control NaSH: ~ 550 mV ORP for full Cu depression); (7) add diesel as Mo collector if needed; (8) start and adjust air to the target flow rate (2 L / min or as needed); (9) float concentration 1 (first scrape of float bubbles) for 2 min in a collection pan (concentration 1) and determine the mass of the concentration 1 before the vacuum dry (mass pull 1); (10) record pH and ORP; (11) replace the collection pan and float concentration 2 for 3 min in a collection pan (concentration 2) and determine the mass of the concentration 2 before the vacuum dry (mass pull 2); and (12) record pH and ORP.

[0171] The XRF (X-Ray Fluorescence) measurement was conducted according to the following procedure: (1) vacuum-dry concentration 1 (float concentration 1) and concentration 2 (float concentration 2), as well as the tailing (depressed mineral), and determine the mass of each material (z.e., the total mineral concentrate is the sum of vacuum-dried concentration 1, vacuum-dried concentration 2, and vacuum-dried tailing); (2) oven-dry the materials overnight at 125°C, and determine the mass of each material; (3) measure and analyze the minerals from each material, and select Cu, Mo, Fe amounts on the XRF device; and (4) analyze Cu, Mo, Fe concentrations and obtain the recovery and grade of these minerals.

[0172] The results of the lab-scale flotation cell tests are summarized in Tables 28-30.Table 28: Flotation Cell Test Results (Study #1)Table 29: Flotation Cell Test Results (Study #2)Table 30: Flotation Cell Test Results (Study #3)

[0173] As detailed in Tables 27-30, the hydrophilic polymer-modified methylated polycarbamide compositions described herein, with and without supplemental depressants, provided similar recovery of Cu and Mo as the control NaSH, and reduced or replaced NaSH at much lower chemical treatment levels. For example, the hydrophilic polymer-modified methylated polycarbamide composition (Candidate 14, Comp. D-4) demonstrated better Cu depression data (lower Cu recovery value) than the control NaSH (Control 2) at 75% lower total chemical treatment levels (than control NaSH level) and exhibited 100% NaSH replacement. The hydrophilic polymer modified and methylated polycarbamide composition with performance enhancing supplement and biopolymer (Candidate 17 in Table 29, Comp. D- 6 with S-TGA) exhibited better Cu depression than the control at 60% total reduced chemical treatment level than the control NaSH and exhibited 100% NaSH replacement. The recovery and grade of Cu and Mo of different conditions including the control were evaluated and reported in Tables 27 - 30. Each study was conducted separately. The study #1 did not use diesel as a molybdenum collector.

[0174] It is possible to utilize the various inventive concepts in combination with one another. Additionally, any particular feature recited as relating to a particularly disclosed aspect of the methods and systems of the present disclosure should be interpreted as available for use with all disclosed aspects of the methods and systems of the present disclosure, unless incorporation of the particular feature would be contradictory to the express terms of the disclosed aspect. Additional advantages and modifications will be readily apparent to those skilled in the art.

[0175] Therefore, the disclosure, in its broader aspects, is not limited to the specific details presented therein, the representative apparatus, or the illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of the general inventive concepts.

[0176] The terminology as set forth herein is for description only and should not be construed as limiting the invention. All references to singular characteristics or limitations of the invention shall include the corresponding plural characteristic or limitation, and vice versa, unless otherwise specified or clearly implied to the contrary by the context in which the reference is made. Unless otherwise specified, “a,” “an,” “the,” and “at least one” are used interchangeably. Furthermore, as used in the description and the appended claims, the singular forms “a,” “an,” and “the” are inclusive of their plural forms, unless the context clearly indicates otherwise.

[0177] To the extent that the term “includes” or “including” is used in the description or the claims, it is intended to be inclusive in a manner similar to the term “comprising” as that term is interpreted when employed as a transitional word in a claim. Furthermore, to the extent that the term “or” is employed (e.g., A or B) it is intended to mean “A or B or both.” When the applicants intend to indicate “only A or B but not both” then the term “only A or B but notboth” will be employed. Thus, use of the term “or” herein is the inclusive, and not the exclusive use.

[0178] All ranges and parameters, including but not limited to percentages, parts, and ratios, disclosed herein are understood to encompass any and all sub-ranges assumed and subsumed therein, and every number between the endpoints. For example, a stated range of “ 1 to 10” should be considered to include any and all sub-ranges beginning with a minimum value of 1 or more and ending with a maximum value of 10 or less (e.g., 1 to 6.1, or 2.3 to 9.4), and to each integer (1, 2, 3, 4, 5, 6, 7, 8, 9, and 10) contained within the range.

[0179] The methods and compositions of the present disclosure can comprise, consist of, or consist essentially of the elements of the invention as described, as well as any additional or optional element described herein, or which is otherwise useful in flotation mining applications.

Claims

CLAIMSThe claimed invention is:

1. A method for the separation and recovery of one or more minerals from a mineral ore bulk material, the method comprising: forming an aqueous pulp comprising water, a mineral ore bulk material, and a separation aid, the separation aid comprising a polycarbamide; agitating and floating the aqueous pulp to form a floated mineral concentrate and flotation tailings; and separately recovering the floated mineral concentrate and flotation tailings.

2. The method of claim 1 , wherein the poly carbamide is formed from the reaction products of formaldehyde and urea.

3. The method of claim 2, wherein the polycarbamide comprises a urea-formaldehyde polycarbamide.

4. The method of claim 2 or claim 3, wherein the polycarbamide has a mole ratio of formaldehyde to urea is from 0.5 to 2.5.

5. The method of any one of claims 2 to 4, wherein the poly carbamide has a mole ratio of formaldehyde to urea is from 0.8 to 2.0.

6. The method of any one of claims 1 to 5, wherein the polycarbamide is an alkylated polycarbamide comprising a reaction product of a urea compound and an alkylating agent.

7. The method of claim 6, wherein the alkylating agent comprises a monohydric aliphatic alcohol containing 1 to 4 carbon atoms.

8. The method of any one of claims 6 or 7, wherein the alkylating agent comprises methanol, ethanol, propanol, isopropanol, n-butanol, and mixtures thereof.

9. The method of any one of claims 6 to 8, wherein the alkylating agent is a methylating agent.

10. The method of any one of claims 6 to 9, wherein the alkylating agent is included in the alkylated polycarbamide in an amount such that a mole ratio of alkylating agent to urea is from 0.01 to 3.0.

11. The method of any one of claims 6 to 10, wherein the alkylating agent is included in the separation aid in an amount from 0.1 wt.% to 30 wt.%, based on the weight of the separation aid.

12. The method of any one of claims 1 to 11, wherein the polycarbamide is modified with at least one biopolymer.

13. The method of claim 12, wherein the biopolymer comprises lignin-based polymer, a polysaccharide, a starch, a hydrocolloid, flour, soy protein, carboxymethylcellulose, or combinations thereof.

14. The method of claim 13, wherein the lignin-based polymer comprises lignosulfonate.

15. The method of claim 13 or 14, wherein the lignin-based polymer is selected from the group consisting of lignosulfonate, calcium lignosulfonate, ammonium lignosulfonate, magnesium lignosulfonate, or mixtures thereof.

16. The method of claim 13, wherein the starch comprises a natural starch, a modified starch, or combinations thereof.

17. The method of any one of claims 12 to 16, wherein the biopolymer is present in the separation aid in an amount from 0.01 wt.% to 30 wt.%.

18. The method of any one of claims 1 to 17, wherein the poly carbamide is modified with a hydrophilic polymer.

19. The method of claim 18, wherein the hydrophilic polymer is an acrylamide polymer.

20. The method of any one of claims 18 to 19, wherein the hydrophilic polymer comprises N-methylolacrylamide polymer, polyacrylamide, sodium polyacrylate, potassium polyacrylate, poly(N,N-dimethylacrylamide, sodium polymethacrylate, or combinations thereof.

21. The method of any one of claims 18 to 20, wherein the hydrophilic polymer is present in the separation aid in an amount from 0.1 wt.% to 20 wt.%.

22. The method of any one of claims 1 to 21, wherein the separation aid further includes a sulfur compound.

23. The method of claim 22, wherein the sulfur compound comprises an ionizable thiol group.

24. The method of claim 22, wherein the sulfur compound comprises a sulfite, a sulfate, a thiol -functional compound, a sulfide, a sulfamate, a sulfinic acid, or combinations thereof.

25. The method of claim 22, wherein the sulfur compound comprises a sulfide, a disulfide, a sulfinic ester, a thiocyanate, a thiocarboxylic acid, a thioester, a sulfinic acid, a dithiocarboxylic acid, a dithiocarboxylic acid ester, a sulfamate, a sulfamide, salts of any of the above, or combinations thereof.

26. The method of claim 24 or 25, wherein the sulfur compound comprises sodium metabisulfite, sodium bisulfite, sodium sulfite, sodium thiosulfate, thiourea, thioureaformaldehyde polymer, sodium thiocyanate, sodium thiocarboxylate, methanethiol, ethanethiol, 2-mercaptoethanol, dimercaptosuccinic acid, cysteine, sodium sulfide, ammonium sulfide, sodium sulfamate, ammonium sulfamate, sodium sulfinate, or combinations thereof.

27. The method of any one of claims 22 to 26, wherein the sulfur compound is included in the separation aid in an amount from 0.1 wt.% to 50 wt.%.

28. The method of any one of claims 1 to 27, wherein the separation aid further comprises a supplemental depressant.

29. The method of claim 28, wherein the polycarbamide and the supplemental depressant are pre-mixed prior to the addition of the separation aid to the aqueous pulp.

30. The method of claim 28 or claim 29, wherein the supplemental depressant comprises thioglycolic acid (TGA) salts, ethylenediaminetetraacetic acid (EDTA) salts, mercaptosuccinic acid (MSA) salts, thioglycerin (TG) salts, or combinations thereof.

31. The method of claim 30, wherein the thioglycolic acid (TGA) salt is selected from the group consisting of sodium thioglycolate (S-TGA), calcium thioglycolate (C-TGA), diethylenetriamine thioglycolate (D-TGA), ammonium thioglycolate (A-TGA), or combinations thereof.

32. The method of claim 28 or claim 29, wherein the supplemental depressant comprises disodium EDTA (S-EDTA), disodium mercaptosuccinate (S-MSA), sodium thioglycerolate (S- TG), or combinations thereof.

33. The method of any one of claims 28 to 32, wherein the supplemental depressant further comprises one or more of sodium hydrosulfide (NaSH), sodium sulfide (Na?S), Nokes reagent, sodium cyanide (NaCN), or combinations thereof.

34. The method of any one of claims 1 to 33, wherein the separation aid is devoid of sodium hydrosulfide (NaSH).

35. The method of any one of claims 1 to 34, wherein the step of forming the aqueous pulp comprises: adding the mineral ore bulk material to the water to form a slurry; mixing the slurry; and adding the separation aid to the slurry while mixing to form the aqueous pulp.

36. The method of any one of claims 1 to 35, wherein the step of agitating and floating the aqueous pulp comprises: introducing air at a suitable flow rate to the aqueous pulp thereby floating the floated mineral concentrate.

37. The method of any one of claims 1 to 36, wherein the floated mineral concentrate recovery is similar or improved compared to that of an otherwise identical method that uses sodium hydrosulfide as a sole separation aid.

28. The method of any one of claims 1 to 37, wherein the flotation tailings recovery is similar or improved compared to that of an otherwise identical method that uses sodium hydrosulfide as a sole separation aid.

39. The method of any one of claims 1 to 38, wherein the floated mineral concentrate comprises molybdenum.

40. The method of any one of claims 1 to 39, wherein the flotation tailings comprise copper, iron (Fe), or combinations thereof.

41. Use of polycarbamide as a separation aid in a mineral ore separation process.

42. The use of a poly carbamide as a separation aid as claimed in claim 35, wherein the polycarbamide is an alkylated polycarbamide.

43. The use of a poly carbamide as a separation aid as claimed in one of claims 41 or 42, wherein the polycarbamide is modified with at least one of a biopolymer and a hydrophilic polymer.

44. A separation aid composition comprising: a polycarbamide comprising a reaction product of formaldehyde and urea, wherein a mole ratio of formaldehyde to urea is from 0.5 to 2.5; and0.1 wt.% to 50 wt.% of a sulfur compound.

45. The separation aid composition of claim 44, wherein the mole ratio of formaldehyde to urea is from 0.8 to 2.0.

46. The separation aid composition of claim 44 or claim 45, wherein the sulfur compound comprises an ionizable thiol group.

47. The separation aid composition of claim 46, wherein the sulfur compound comprises a sulfite, a sulfate, a thiol-functional compound, a sulfide, a sulfamate, a sulfinic acid, or combinations thereof.

48. The separation aid composition of any one of claims 44 or 45, wherein the sulfur compound comprises a sulfide, a disulfide, a sulfinic ester, a thiocyanate, a thiocarboxylic acid, a thioester, a sulfinic acid, a dithiocarboxylic acid, a dithiocarboxylic acid ester, a sulfamate, a sulfamide, salts of any of the above, or combinations thereof.

49. The separation aid composition of any one of claims 44 to 48, wherein the polycarbamide is an alkylated polycarbamide comprising a reaction product of a urea compound and an alkylating agent.

50. The separation aid composition of claim 49, wherein the alkylating agent comprises a monohydric aliphatic alcohol containing 1 to 4 carbon atoms.

51. The separation aid composition of any one of claims 49 to 50, wherein the alkylating agent comprises methanol, ethanol, propanol, isopropanol, n-butanol, and mixtures thereof.

52. The separation aid composition of any one of claims 49 to 51, wherein the alkylating agent is a methylating agent.

53. The separation aid composition of any one of claims 49 to 52, wherein the alkylating agent is present in the separation aid composition in an amount from 0.1 wt.% to 30 wt.%, based on the total weight of the separation aid composition.

54. The separation aid composition of any one of claims 49 to 53, wherein alkylating agent is present in the separation aid in an amount from 0.5 wt.% to 20 wt.%, based on the total weight of the separation aid composition.

55. The separation aid composition of any one of claims 44 to 54, wherein the separation aid further includes 0.01 wt.% to 30 wt.% of a biopolymer.

56. The separation aid of claim 55, wherein the biopolymer comprises lignin-based polymer, a polysaccharide, a starch, a hydrocolloid, flour, soy protein, carboxymethylcellulose, or combinations thereof.

57. The separation aid of claim 56, wherein the lignin-based polymer comprises lignosulfonate.

58. The separation aid of claim 56 or claim 57, wherein the lignin-based polymer is selected from the group consisting of lignosulfonate, calcium lignosulfonate, ammonium lignosulfonate, magnesium lignosulfonate, or mixtures thereof.

59. The separation aid composition of claim 56, wherein the starch comprises a natural starch, a modified starch, or combinations thereof.

60. The separation aid composition of any one of claims 44 to 59, wherein the separation aid further includes 0.1 wt.% to 20 wt.% of a hydrophilic polymer, based on the total weight of the polycarbamide.

61. The separation aid of claim 60, wherein the hydrophilic polymer comprises an acrylamide polymer.

62. The separation aid of claim 60 or claim 61, wherein the hydrophilic polymer comprises N-methylolacrylamide polymer, polyacrylamide, sodium polyacrylate, potassium polyacrylate, poly(N,N-dimethylacrylamide, sodium polymethacrylate, or combinations thereof.

63. The separation aid composition of any one of claims 44 to 62, wherein the separation aid composition further comprises a supplemental depressant.

64. The separation aid composition of claim 63, wherein the separation aid composition comprises from 0.1 wt.% to 50 wt.% of the supplemental depressant, based on the total weight of the separation aid composition.

65. The separation aid composition of claim 63 or claim 64, wherein the supplemental depressant comprises thioglycolic acid (TGA) salts, ethylenediaminetetraacetic acid (EDTA) salts, mercaptosuccinic acid (MSA) salts, thioglycerin (TG) salts, or combinations thereof.

66. The separation aid composition of claim 65, wherein the thioglycolic acid (TGA) salt is selected from the group consisting of sodium thioglycolate (S-TGA), calcium thioglycolate (C-TGA), diethylenetriamine thioglycolate (D-TGA), ammonium thioglycolate (A-TGA), or combinations thereof.

67. The separation aid composition of any one of claims 63 to 66, wherein the supplemental depressant comprises disodium EDTA (S-EDTA), disodium mercaptosuccinate (S-MSA), sodium thioglycerolate (S-TG), or combinations thereof.

68. The separation aid composition of any one of claims 44 to 67, wherein the composition is devoid of sodium hydrosulfide (NaSH).

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