New frother for mineral recovery and method of making and using the same

Abstract

The present invention relates to a composition comprising at least one compound of formula (I), and to the use of said composition for recovering valuable minerals from ores and other raw materials by flotation.

Description

[0001] The present invention relates to a composition comprising at least one compound of formula (I), and to the use of said composition for recovering valuable minerals from ores and other raw materials by flotation. Background Art

[0002] Froth flotation is a process for concentrating valuable minerals, which are generally referred to as "valuable minerals". The valuable mineral or minerals are the metal, metals, mineral or minerals that are the primary subject of the flotation process, i.e. the metals and minerals from which it is desired to remove impurities.

[0003] A typical froth flotation process involves mixing an aqueous slurry containing finely ground ore particles with a "frother" or foaming agent to produce froth. The grinding is usually carried out in water, with the resulting slurry being referred to as "pulp". The slurry is processed in flotation cells, which agitate the mixture and introduce air in the form of small bubbles. Ore particles containing one or more valuable minerals are preferentially attracted to the froth due to the affinity between the froth and the minerals exposed on the surface of the ore particles. The valuable minerals are then collected by separation from the froth to obtain a concentrate, while the gangue particles, which have little or no affinity for the froth, sink or remain in the liquid to obtain a tailing.

[0004] Separation by froth flotation is based on the selective attachment of gas bubbles to the surfaces of target valuable mineral particles in a mineral / water slurry.

[0005] Froth flotation is a versatile process that can be used to separate a variety of valuable minerals. In fact, the affinity of the mineral particle surface for the froth to which the particle is exposed can be selectively enhanced by chemical treatment, for example by changing the hydrophobicity of the mineral particle surface. By way of example only to illustrate the versatility of the process, froth flotation is used to separate sulfide minerals from silica gangue and to recover coal from slurries of coal and silica (raw coal), which slurries include, for example, carbonaceous materials with a high ash content, shales, clays and other non-carbonaceous impurity minerals (such as kaolinite, quartz, dolomite, calcite, muscovite, pyrite and microcline).

[0006] Frothing agents are used to provide the alkaline foam phase required to carry out the process, while other agents are used to control the relative hydrophilicity of the particles and maintain appropriate foam characteristics. Among these agents, one may cite - (i) collectors, which may be nonionic compounds, amphoteric compounds, anionic compounds, cationic compounds and mixtures thereof; - (ii) modifiers, which may be activators or depressants, i.e., they may increase or decrease the adsorption of the collector on a given mineral surface.

[0007] The frothers can be selected from alcohols, polyethylene glycols, alkoxy-substituted alkanes, organic acids and amines. However, they are usually selected from alcohols, polyethylene glycols and alkoxy-substituted alkanes because they have practically no collecting properties (collectors), which is not the case, for example, with organic acids and amines. Suitable frothers for different applications can be found in Minerals 2018, 8(2), 53: "Classification of Flotation Frothers". MIBC, i.e. 4-methyl-2-pentanol, is one of the most commonly used flotation frothers for coal, metal sulfide or non-sulfide flotation.

[0008] Industrially, froth flotation is a multi-stage process comprising - (i) a roughing stage, wherein the process is designed to produce a concentrate with a high recovery of valuable minerals (yields typically exceed 90%) - (ii) optional regrinding of the concentrate obtained in the roughing stage - (iii) a cleaning stage, wherein the process is designed to optionally regrind the rougher concentrate to produce a higher grade concentrate. Cleaning can be repeated several more times until a saleable concentrate is produced. In the case of copper, a saleable concentrate is typically in the range of 15% to 38% Cu.

[0009] Strong frothers are typically used in the roughing stage to recover valuable minerals at high yields. More particularly, strong frothers are effective for recovering coarse particles, i.e. particles of relatively large size (i.e. particles generally considered to have a diameter > 100 μm).

[0010] After the regrinding stage, the size of the coarse particles is now much finer. Weak frothers are often used in the cleaning stage to recover valuable minerals with high selectivity, thereby providing a high grade concentrate. However, frothers are typically carried over (and therefore continue) from the roughing stage into the regrinding and cleaning stages.

[0011] It is generally believed that commercially available frothers have either too weak a frothering property resulting in poor recovery (e.g., in the roughing stage) or too strong a frothering property resulting in poor selectivity (e.g., in the cleaning stage). In practice, plants typically use a combination of strong and weak frothers, selected to balance the needs of the roughing and cleaning stages. Therefore, there is a need for new frothers and new frother compositions.

[0012] There is a need for new compositions comprising one or more strong frothers that can be used to recover valuable minerals at high yields by froth flotation. Ideally, such compositions should be effective in recovering coarse particles of valuable minerals.

[0013] The availability of such stronger frothers and such compositions will allow for the processing of less finely ground ore particles during the flotation process and will therefore allow for a reduction in costs associated with energy consumed during more vigorous ore grinding conditions. In addition, due to the reduced specific surface area of ​​the coarse particles compared to the specific surface area of ​​the finer particles, less collector will be required during the flotation process, which will represent an economic and environmental advantage.

[0014] There is also a need for new compositions comprising one or more strong frothers which can be used in sufficient amounts to give a strong foaming behavior in the roughing stage without impairing the processes in the downstream cleaning stage. Indeed, the possibility of using said frothers in sufficient amounts to give a strong foaming behavior should contribute to a high recovery of valuable minerals in the roughing stage and to an increased recovery of coarse particles of valuable minerals.

[0015] Typically, the strong frother used in the roughing stage persists downstream in the flotation cell during the cleaning stage. It then results in lower selectivity in the circuit, an operating trade-off in which less "aggressive" operation is performed (i.e., increasing froth depth and reducing airflow) at the expense of recovery, and over-foaming (i.e., excessive foam formation), which is detrimental to the overall process by reducing selectivity in the cleaning stage and / or causing overflow of the cleaner cell. In some cases, large amounts of defoamers (antifoaming agents) need to be used in the cleaning circuit to control the excessive foam, resulting in additional costs.

[0016] There is also a need for strong foaming agents that can be converted / decomposed into less strong foaming agents, or weak foaming agents or even non-foaming agents throughout the process, and especially between the roughing and cleaning stages.

[0017] The availability of such "cleavable" stronger frothers would give the possibility to use them in sufficient amounts to produce strong foaming behavior, thereby contributing to high recovery of valuable minerals and improving the coarse particle recovery of valuable minerals in the roughing stage, and helping to avoid the possibility of excessive foaming and reduced selectivity in further stages (such as the cleaning stage).

[0018] Finally, there is a need for blowing agent compositions that are less volatile and have a higher flash point than currently available blowing agent compositions. In fact, for safety reasons, it is highly desirable to reduce the flammability of blowing agent compositions during storage or during use of the composition. For purposes of example only, the commonly used blowing agent MIBC is a highly flammable compound with a flash point of 41°C. Summary of the invention

[0019] Applicants have unexpectedly discovered that compositions according to the present invention can meet all of these needs and more.

[0020] Thus, in a first aspect, the present invention relates to a composition comprising at least one compound of formula (I):

[0021]

[0022] in:

[0023] A represents a C1-C8 alkanediyl group which may be linear, branched or cyclic,

[0024] B may be the same or different at each occurrence and represents a C1-C8 alkanediyl group which may be linear, branched or cyclic,

[0025] R represents H or a C1-C8 alkyl group which may be a straight chain or branched chain,

[0026] n is an integer ≥ 1 and ≤ 100, and

[0027] R1 represents a C4-C20 hydrocarbon group having a carbonyl group inserted therein.

[0028] In a second aspect, the present invention relates to a froth flotation process for recovering valuable minerals from ores and other raw materials, the process comprising adding to said ore or other raw material a composition as previously defined.

[0029] In a third aspect, the present invention relates to the use of a composition as previously described for recovering valuable minerals from ores and other raw materials by flotation.

[0030] Compositions comprising a compound of formula (I)

[0031] The composition according to the invention comprises at least one compound of formula (I) as disclosed above.

[0032] Typically, in formula (I), A represents a C1-C8 alkanediyl group which may be linear, branched or cyclic. Preferably, A is selected from the list consisting of: -CH2-, -CH2-CH2-, -CH2-CH2-CH2-, -CH2-CH2-CH2-CH2-, -CH2-CH2-CH2-CH2-, -CH(CH3)- and -C(CH3)2-. More preferably, A is selected from the list consisting of: -CH2-, -CH2-CH2-, -CH2-CH2-CH2- and -CH(CH3)-, even more preferably, A represents -CH2- or -CH2-CH2-CH2-, most preferably, A represents -CH2-.

[0033] Typically, B may be identical or different at each occurrence and represents a C1-C8 alkanediyl group which may be linear, branched or cyclic. Preferably, B is selected from the list consisting of: -CH2-CH2-, -CH2-CH(CH3)-, -CH(CH3)-CH2- and -CH2-CH2-CH2-CH2-. More preferably, B represents -CH2-CH2- or -CH2-CH(CH3)- and even more preferably B represents -CH2-CH2-.

[0034] Good results were obtained with compounds of formula (I) in which A represents -CH2- or -CH2-CH2-CH2- and B represents -CH2-CH2- or -CH2-CH(CH3)-, in particular in which A represents -CH2- and B represents -CH2-CH2-.

[0035] Typically, in formula (I), R represents H or may be a linear or branched C1-C8 alkyl group. In some preferred embodiments, R is H. In some other preferred embodiments, R is selected from the list consisting of: methyl, ethyl, propyl, isopropyl, sec-butyl, tert-butyl, isobutyl and n-butyl.

[0036] Good results were obtained with compounds of formula (I) in which A represents -CH2- or -CH2-CH2-CH2-, B represents -CH2-CH2- or -CH2-CH(CH3)-, and R is H. In particular, good results were obtained with compounds of formula (I) in which A represents -CH2-, B represents -CH2-CH2-, and R is H.

[0037] Typically, in formula (I), R1 represents a C4-C20 hydrocarbon group optionally intercalated with a carbonyl group. In some embodiments, R1 represents a C4-C20 alkyl group optionally intercalated with a carbonyl group, which may be linear, branched or cyclic. In some other embodiments, R1 represents a C4-C20 alkenyl group, which may be linear, branched or cyclic. Still in other embodiments, R1 represents an alkylated aryl group.

[0038] In some preferred embodiments, R1 is selected from the list consisting of:

[0039]

[0040]

[0041] In some more preferred embodiments, R1 is selected from the list consisting of:

[0042]

[0043]

[0044] In some even more preferred embodiments, R1 is selected from the list consisting of:

[0045]

[0046] In the most preferred embodiment, R1 is selected from the list consisting of:

[0047]

[0048] Good results were obtained with a composition comprising at least one compound of formula (I) in which A represents -CH2- or -CH2-CH2-CH2-, B represents -CH2-CH2-, R represents H and R1 is

[0049]

[0050] Typically, in formula (I), n is an integer ≥1 and ≤100. Preferably, n is an integer ≥1 and ≤50; more preferably, ≥1 and ≤20; even more preferably, ≥1 and ≤10; still more preferably, ≥1 and ≤6, and most preferably, n is an integer ≥1 and ≤4.

[0051] In some preferred embodiments, the composition according to the present invention comprises at least one compound selected from the list consisting of:

[0052]

[0053] In some embodiments, the compositions according to the present invention further comprise at least two compounds of formula (I).

[0054] Merely as an example, the synthesis of compounds of formula (I) according to the invention can be carried out by the following different routes A to E.

[0055] Route A

[0056]

[0057] Route B

[0058]

[0059] Route C

[0060]

[0061] Route D

[0062]

[0063] Route E

[0064]

[0065] In the above routes A to E, R, R1, A, B and n are as previously defined.

[0066] The skilled person can easily adjust the reaction conditions to obtain the desired product with high yield. The skilled person can also find other reaction pathways for preparing the compounds according to the present invention.

[0067] More complete details on some of the reaction conditions are given in the Experimental Section.

[0068] In some other embodiments, the composition according to the present invention further comprises at least one compound selected from the group consisting of: a foaming agent, a collector, water, a compatibilizer, a defoamer, a dispersant, a pH regulator, a rheology regulator, a surfactant, an activator, an inhibitor, a lubricant, an antiscalant and a preservative. Preferably, the compound is selected from a collector and / or a foaming agent.

[0069] The blowing agent may be selected from the list consisting of phenols, alkyl sulfonates, fatty alcohols, cyclic alcohols, alkoxyalkanes, polyethylene glycols, polypropylene glycols, polyethylene glycol ethers, polypropylene glycol ethers, polyethylene glycol glycerol ethers, pyridine derivatives and mixtures thereof.

[0070] Without limitation, the foaming agent may be selected from:

[0071] (i) Phenols, such as o-cresol, m-cresol, p-cresol, xylenol and phenol;

[0072] (ii) alkyl sulfonates, in particular alkyl aryl sulfonates;

[0073] (iii) fatty alcohols, such as n-butanol, n-pentanol, isopentanol, n-hexanol, 2-ethylhexanol, n-heptanol, methyl isobutyl carbinol (MIBC), octanoic acid, 4-heptanol, mixtures of C4-C7 alcohols and mixtures of C5-C8 alcohols;

[0074] (iv) cyclic alcohols, such as terpineol and borneol;

[0075] (v) alkoxyalkanes, for example 1,1,3-triethoxybutane (TEB) and 1,3,5-trialkoxypropyltrioxane;

[0076] (vi) Polyethylene glycol, polyethylene glycol ethers, e.g.

[0077] R2(X) m OH, where R2=H or C n H 2n+1 And X = EO (ethylene oxide), PO (propylene oxide), BO (butylene oxide),

[0078]

[0079] (vii) pyridine derivatives;

[0080] (viii) and mixtures thereof.

[0081] Collectors may be included in the compositions according to the invention. Without wishing to be bound by theory, collectors are agents used to selectively adsorb to the surface of particles to enhance their hydrophobic behavior and increase affinity with foam. Choosing the right collector is critical for effective separation by froth flotation.

[0082] Suitable collectors may be selected from the list consisting of nonionic collectors, anionic collectors, cationic collectors, amphoteric collectors and mixtures thereof.

[0083] Merely by way of example, the nonionic collector may be a hydrocarbon oil such as fuel oil, kerosene or a small molecule like isopropyl ethylthiocarbamate (IPETC).Nonionic collectors are widely used in the flotation of, for example, coal, molybdenite, elemental sulfur, copper and talc.

[0084] Anionic collectors are usually acids or acid salts that ionize in water and can be selected from

[0085] (i) organic sulfur compounds, such as xanthates (e.g. ethylxanthate), monothiophosphates, monothiophosphinates, dithiophosphates, dithiophosphinates, dithiocarbamates, trithiocarbonates, alkyl sulfates, sulfonates, sulfosuccinates, sulfosuccinates, usually in the form of sodium, potassium or ammonium salts,

[0086] - (ii) organic phosphorus compounds, such as phosphonic acids and phosphates, usually in the form of sodium, potassium or ammonium salts,

[0087] (iii) carboxylic acids, for example capric acid, lauric acid, myristic acid, oleic acid, stearic acid, palmitic acid, linoleic acid, synthetic saturated or unsaturated fatty acids, tall oil, usually as sodium, potassium or ammonium salts, such as sodium oleate,

[0088] - (iv) mixtures thereof.

[0089] By way of example only, xanthate salts are particularly selective collectors for sulfide minerals, while sodium oleate is typically used for the flotation of oxide minerals.

[0090] Cationic collectors usually carry a positively charged amine group, which can be a primary amine, a secondary amine, or a tertiary amine group. Quaternary ammonium salts can also be used as cationic collectors. Cationic collectors are used, for example, in the flotation of silicates and rare metal oxides.

[0091] Amphoteric collectors are compounds with one or more cationic functional groups and one or more anionic functional groups. Common types are long-chain amino acids, such as cetyl glycine, N-lauryl-ρ-aminopropionic acid, N-lauryl-β-iminodipropionic acid, N-lauryl-β-aminobutyric acid or long-chain aminosulfonic acids such as N-myristyl taurine.

[0092] Certain other agents, referred to as "modifiers," may be included in compositions according to the present invention to enhance separation and recovery of desired minerals and / or metals. Modifiers, which may include pH adjusters, may be used to alter and control the pH of the slurry to enhance separation and recovery of desired minerals and / or metals. Rheology modifiers may be used to alter and control the rheology of the slurry to enhance separation and recovery of desired minerals and / or metals.

[0093] In some cases, compounds referred to as "activators" and "inhibitors" may be added to the compositions according to the present invention.

[0094] A typical activator is a specific compound used to activate a certain valuable mineral. As an example, copper sulfate is used to enhance the collector coating on a specific valuable sulfide.

[0095] Inhibitors generally prevent the adsorption of collectors to specific mineral surfaces; they serve to improve selectivity. As suitable inhibitors, cyanide, lime added as CaO or Ca(OH)2, starch and lignin may be cited.

[0096] In some other embodiments, compositions according to the present invention comprise water.

[0097] The composition may also contain some other products, such as products from side reactions of the synthesis of the compound having formula (I).

[0098] Froth flotation method

[0099] In a second aspect, the present invention relates to a flotation process for recovering valuable minerals from ores and other raw materials, the process comprising adding to the ores and other raw materials a composition comprising at least one compound having formula (I):

[0100] (I)

[0101] wherein A, B, R, R1 and n are as previously defined.

[0102] The flotation method according to the invention is intended to recover valuable minerals from ores and other raw materials.

[0103] In some embodiments, the flotation method according to the invention comprises adding to the ore in the form of crushed ore, ground ore and / or aqueous slurry a composition comprising at least one compound of formula (I) having all possible characteristics and all possible embodiments that have been previously described.

[0104] In some other embodiments, the flotation method according to the invention comprises adding to any other feedstock a composition comprising at least one compound of formula (I) having all possible characteristics and all possible embodiments that have been previously described.

[0105] The term valuable mineral refers to the metal, metals, mineral, minerals, energy mineral or energy minerals that are the primary subject of the flotation process, ie the metals, minerals and energy minerals from which it is desired to remove impurities.

[0106] In some embodiments, the valuable mineral is a sulfide mineral, a non-sulfide mineral, or a native metal.

[0107] In some preferred embodiments, the valuable mineral is a sulfide mineral, and the sulfide mineral raw material / ore is, for example, a sulfide ore, a historical tailing, a cyclone separator underflow, a sinker, etc., or a combination thereof. Sulfide mineral raw materials / ores include Cu-Mo ores, Cu-Au ores, native Au ores, platinum group metal ores. Cu ores, Ni ores, Ni-Cu ores, and ores including Pb, Zn, Cu and / or Ag. Valuable metals of interest include, for example, gold, silver, platinum, palladium, other platinum group metals, copper, nickel, molybdenum, cobalt, lead, and zinc. Valuable mineral raw materials / ores consist of: copper-containing minerals such as chalcopyrite, chalcocite, bornite, covellite; gold-containing minerals such as argillite, pyrite, marcasite, Cu sulfide minerals and arsenopyrite; molybdenum-containing minerals such as molybdenite; lead-containing minerals such as galena; zinc-containing minerals such as sphalerite and sphalerite; silver-containing minerals such as argillite, silver-tetrahedrite, silver-containing pyrite and silver-containing galena; nickel-containing minerals such as pentlandite; minerals containing platinum group metals such as arsenopyrite; or combinations thereof.

[0108] In some other preferred embodiments, the valuable mineral is a non-sulfide mineral, and the raw material / ore is a non-sulfide mineral raw material / ore. The term non-sulfide mineral includes minerals belonging to the following categories: oxides, silicates, sulfates, phosphates, carbonates and halides. By way of example only, non-sulfide mineral raw materials / ores include phosphates, iron oxides, kaolinite and bentonite, spodumene, potash, borates, trona, fluorite, calcite, dolomite, limestone, barite, mica, feldspar, quartz, silica sand, monazite, kyanite, magnesite, chromite, bauxite, ilmenite, rutile, manganese oxide, graphite, talc and cassiterite.

[0109] Also in some preferred embodiments, the valuable mineral is a native metal and the raw material / ore is, for example, a gold, silver or copper raw material / ore.

[0110] In some other embodiments, the valuable mineral is an energy mineral (such as coal) and the valuable mineral feedstock is a slurry of coal and silica (raw coal), which slurry includes, for example, carbonaceous materials with a high ash content, shale, clay and other non-carbonaceous impurity minerals (such as kaolinite, quartz, dolomite, calcite, muscovite, pyrite and microcline).

[0111] The raw coal may be high-rank coal (such as anthracite or hard coal), medium-rank coal (such as bituminous coal), or low-rank coal (such as sub-bituminous coal, lignite or also known as brown coal).

[0112] In a third aspect, the present invention relates to the use of a composition comprising at least one compound of formula (I) for recovering valuable minerals from ores and other raw materials by flotation:

[0113] (I)

[0114] wherein A, B, R, R1 and n are as previously defined.

[0115] The use according to the invention relates to a composition having all possible features and all possible embodiments which have been described previously.

[0116] The present invention will now be described in more detail with reference to the following examples, which are not intended to be limiting.

[0117] Examples

[0118] Preparation of "cleavable" foaming agent

[0119] Synthesis of 4-Methylpentan-2-yl 2-hydroxyacetate (MIBC glycolate)

[0120]

[0121] In a 500-mL round-bottom flask, glycolic acid (13.8 g, 180 mmol, 1 equivalent), 4-methyl-2-pentanol (MIBC) (37.6 g, 360 mmol, 2 equivalents) and toluene (230 mL) were added in sequence, followed by sulfuric acid (96%) (1 mL, 18 mmol, 0.1 equivalent). The resulting solution was heated under reflux, and water was removed azeotropically using a Dean-Stark apparatus. After 3 h, water had completed distillation, and the reaction mixture was allowed to cool to room temperature. The resulting solution was washed with a saturated NaHCO3 aqueous solution (twice), followed by a saturated NaCl aqueous solution. The organic phase was dried over anhydrous magnesium sulfate, and volatiles (toluene and excess MIBC) were removed under vacuum. The crude product was purified by flash chromatography on silica gel to produce the first fraction (15 g, 52% yield) of the desired MIBC glycolate as a colorless liquid.

[0122] Alternative Synthesis of 4-Methylpent-2-yl 2-hydroxyacetate (MIBC glycolate)

[0123]

[0124] In a 250-mL round-bottom flask, glycolic acid (30.4g, 396mmol, 1 equivalent), 4-methyl-2-pentanol (MIBC) (200mL, 1.54mol, 4 equivalents) and sulfuric acid (96%) (1.1mL, 20mmol, 0.05 equivalents) were added sequentially. The resulting solution was heated at 130 ° C for 6h. The reaction mixture was then allowed to cool to room temperature, and calcium carbonate (4.5g) was added, and the resulting suspension was stirred overnight. The white solid in the suspension was then filtered, and excess MIBC was removed under vacuum. The remaining crude product was purified by distillation to give MIBC glycolate (36g, 57% yield) as a colorless liquid.

[0125] Synthesis of 4-methylpentan-2-yl 4-hydroxybutyrate (MIBC hydroxybutyrate)

[0126]

[0127] In a 250-mL round-bottom flask, γ-butyrolactone (GBL) (20 g, 230 mmol, 1 eq.), 4-methyl-2-pentanol (MIBC) (100 g, 979 mol, 4 eq.) and sulfuric acid (96%) (0.5 g, 4.9 mmol, 0.02 eq.) were added in sequence. The resulting solution was stirred at room temperature for 14 h, after which equilibrium was reached (GBL / ester = 63:37, by 1H NMR). Calcium carbonate (3 g) was then added and the resulting suspension was stirred for 1 h. The white solid in the suspension was then filtered and the filtrate was diluted with AcOEt (200 mL). The organic phase was washed with Na2CO3 solution (1% in water, 100 mL), water (2×100 mL), and finally with saturated NaCl solution (100 mL). The organic phase was then dried over MgSO4, filtered, and the resulting oil was purified by flash chromatography on silica gel to give the desired product (13 g, 30% yield) as a colorless oil.

[0128] Synthesis of ethyl 2-(2-hydroxyethoxy)acetate

[0129]

[0130] As described in J. Photosci. [Journal of Photopolymer Science and Technology] 2000, 7, 143-148.

[0131] Synthesis of 4-methylpentan-2-yl 2-(2-hydroxyethoxy)acetate (foaming agent 1)

[0132]

[0133] In a 100-mL round-bottom flask, ethyl 2-(2-(2-hydroxyethoxy)ethoxy)acetate (20 g, 132 mmol, 1 eq), 4-methyl-2-pentanol (MIBC) (52.1 g, 565 mmol, 4.3 eq) and sulfuric acid (96%) (0.7 mL, 12.6 mmol, 0.1 eq) were added sequentially. The resulting solution was heated at 50 °C for 24 h. The reaction mixture was then allowed to cool to room temperature, and calcium carbonate (15 g) was added, and the resulting suspension was stirred overnight. The white solid in the suspension was then filtered, and excess MIBC was removed under vacuum. [Be careful at this step, as remaining traces of acidity or overheating will cause the product to cyclize and release MIBC.] The remaining crude product (7.8 g) was purified by flash chromatography on silica gel to give the desired product (6.2 g, 23% yield) as a colorless liquid.

[0134] Synthesis of ethyl 2-(2-(2-hydroxyethoxy)ethoxy)acetate

[0135]

[0136] As described in Langmuir 2013, 29, 13111-13120.

[0137] Synthesis of 4-methylpentan-2-yl 2-(2-(2-hydroxyethoxy)ethoxy)acetate (foaming agent 2)

[0138]

[0139] In a 250-mL round-bottom flask, ethyl 2-(2-(2-hydroxyethoxy)ethoxy)acetate (30.3 g, 155 mmol, 1 eq.), 4-methyl-2-pentanol (MIBC) (125.1 g, 156 mL, 1.2 mol, 8 eq.) and sulfuric acid (96%) (0.4 mL, 7.2 mmol, 0.05 eq.) were added sequentially. The resulting solution was heated at 90 ° C for 24 h. The reaction mixture was then allowed to cool to room temperature, and calcium carbonate (5 g) was added, and the resulting suspension was stirred overnight. The white solid in the suspension was then filtered, and excess MIBC was removed under vacuum. The remaining crude product (32.2 g) was purified by flash chromatography on silica gel to give the desired product (25.4 g, 66% yield) as a colorless liquid.

[0140] Synthesis of ethyl 2-(2-(2-(2-hydroxyethoxy)ethoxy)ethoxy)ethyl acetate

[0141]

[0142] As described in Langmuir 2013, 29, 13111-13120.

[0143] Synthesis of 4-methylpentan-2-yl 2-(2-(2-(2-hydroxyethoxy)ethoxy)ethoxy)acetate (foaming agent 3)

[0144]

[0145] In a 250-mL round-bottom flask, ethyl 2-(2-(2-(2-hydroxyethoxy)ethoxy)ethoxy)acetate (15 g, 63.5 mmol, 1 eq), 4-methyl-2-pentanol (MIBC) (26 g, 156 mL, 254 mmol, 4 eq), toluene (150 mL) and sulfuric acid (96%) (0.38 mL, 6.8 mmol, 0.1 eq) were added sequentially. The resulting solution was heated under reflux and ethanol was removed azeotropically using a Dean-Stark apparatus. After 10 h, the reaction mixture was allowed to cool to room temperature. Calcium carbonate (4 g) was added and the resulting suspension was stirred overnight. The white solid in the suspension was then filtered and excess MIBC was removed under vacuum. The remaining crude product (22.3 g) was purified by flash chromatography on silica gel to give the desired product (7.6 g, 35% yield) as a colorless liquid.

[0146] Synthesis of 4-methylpentan-2-yl 2-(2-(2-hydroxyethoxy)ethoxy)acetate (foaming agent 4)

[0147]

[0148] In a 500-mL round-bottom flask, ethyl 2-(2-(2-hydroxyethoxy)ethoxy)acetate (16 g, 83 mmol, 1 eq), isoamyl alcohol (18 mL, 165 mmol, 2 eq) and toluene (150 mL) were added sequentially, followed by sulfuric acid (96%) (0.5 mL, 9 mmol, 0.1 eq). The resulting solution was heated under reflux, and ethanol was removed azeotropically using a Dean-Stark apparatus. After 2 h, the reaction mixture was allowed to cool to room temperature. The resulting solution was washed with saturated NaHCO3 aqueous solution (twice) followed by saturated NaCl aqueous solution. The organic phase was dried over anhydrous magnesium sulfate, and volatiles (toluene and excess isoamyl alcohol) were removed under vacuum. The crude product was purified by flash chromatography on silica gel to give the desired product (11 g, 54% yield) as a colorless liquid.

[0149] Flash point determination

[0150] The flash point of MIBC glycolate was determined using ASTM method D3828-87, Method B, Limited Flash Point Method, also known as the Setaflash Closed Cup Method. Approximately 2 mL of sample was placed in the cup and tested at 22°C, 35°C, 50°C, 70°C, 80°C, 85°C, and 87°C. The lowest temperature at which headspace combustion was observed was defined as the flash point.

[0151] MIBC glycolate, which has a flash point of 87° C., is much less flammable than MIBC, which has a flash point of 41° C. Ethoxylated derivatives of MIBC glycolate, such as blowing agents 1 to 3, are even less flammable than MIBC. This is very advantageous for safety reasons during storage and transport or when using blowing agents of this type.

[0152] Hydrolysis of "cleavable" foaming agents

[0153] In a 100 mL flask were added DI water (50 g), Ca(OH)2 for adjusting the pH to 12, and a "cleavable" bubbling agent (20 μL). The resulting solution was stirred at room temperature for a period of 24 h, after which complete hydrolysis was achieved (detected by LC-MS when the ester peak disappeared).

[0154] The resulting solution was used in flotation tests to evaluate the flotation performance of the "cleavable" frother after hydrolysis.

[0155] Flotation test

[0156] Prior to flotation testing in the Denver flotation cell, 1 Kg of Cu-Mo ore sample was crushed to 2 mm and 0.6 g of Ca(OH)2 was ground in a laboratory stainless steel ball mill in the presence of 675 ml of water to achieve 80% grinding through 212 μm. The pH of the resulting slurry was 9.8. The ground slurry was transferred to a flotation cell with a capacity of 2.7 L and diluted to a solid content of 32%. The impeller speed was set to 1000 r / min and the slurry was stirred. The reagent addition strategy and flotation procedure were as follows: the collector was added to the flotation slurry and the slurry was homogenized for 1 min; then, the frother was added and the slurry was homogenized for another 45 s. The air flow was turned on and the foam was scraped off every 15 seconds for a total of seven minutes to collect the Cu concentrate. In all tests, the air flow rate supplied to the flotation cell was maintained at a flow rate of 3.25 L / min. The slurry level was maintained at the same level by adding water.

[0157] After testing, the concentrate and tailings were filtered, dried, weighed and analyzed for Cu content.

[0158] The Cu ore information used in the flotation tests is presented in Table 1.

[0159] Table 1. Assays for the Cu-Mo ores used in the flotation tests.

[0160] Ore stone determination Cu wt.% Fe wt.% Mo ppm Gangue wt.% Cu-Mo ore 0.45 4.62 62 79.04

[0161] The water recovery (% water recovery) was determined using the following equation: ：

[0162]

[0163] in:

[0164] C = concentrate (water + solids) collected as a function of time;

[0165] Dry C(g) = solids after drying of concentrate;

[0166] W = total mass of water added to the pool.

[0167] Copper recovery (Cu recovery wt.%), copper concentrate grade (Cu grade wt.%) are determined by analyzing the Cu content in ore, concentrate and tailings.

[0168] The coarse particle recovery % was determined by passing the collected concentrate through a 212 μm sieve.

[0169] result

[0170] Flotation tests were conducted using isopropyl ethylthiocarbamate (IPETC) as the collector.

[0171] Blends of glycol ethers are well known in the industry as strong foaming agents, and methyl isobutyl carbinol (MIBC) is well known as a weak foaming agent. 68 (AF68-blended glycol ether) or 70 (AF70-MIBC) was used as a "strong" or "weak" foaming agent for comparative examples.

[0172] The first flotation test was conducted at pH 9.5, a relatively low pH chosen to simulate the pH conditions of the rougher stage.

[0173] Table 2. Flotation test results of “cleavable” frothers before hydrolysis*

[0174]

[0175] *Floatation at pH 9.5 for 7 minutes.

[0176] **Blend consisting of solution containing 6 ppm MIBC glycolate, 4 ppm Froth Agent 1, 6 ppm Froth Agent 2, and 5 ppm Froth Agent 3.

[0177] ***Particle size>212μm.

[0178] The results of Table 2 show that, unexpectedly, foamers 1, 2, and 3 are strong foamers, which allow higher water recoveries than MIBC, and more unexpectedly than blended glycol ethers. Even more unexpectedly, blends of MIBC glycolate and foamers 1 to 3 show even higher water recoveries.

[0179] Furthermore, the Cu recoveries and Cu grades were similar for flotations with frother 1, frother 2, frother 3, frother 4 and blends of MIBC glycolate and frothers 1 to 3, respectively, and for flotations with blended glycol ethers.

[0180] Finally, frothers 2 and 3 are strong frothers, which allowed higher coarse particle recoveries than MIBC, and in the case of frother 3, surprisingly even higher coarse particle recoveries than the blended glycol ethers. Surprisingly, blends of MIBC glycolate and frothers 1 to 3 allowed high coarse particle recoveries, similar to those obtained with the blended glycol ethers.

[0181] Frother 4 had an intermediate behavior, ie, water recoveries were close to those of MIBC, and Cu recoveries and Cu grades were similar to those obtained with blended glycol ether flotation.

[0182] As described, the hydrolysis of foaming agents 1 to 4 was carried out at pH 12 by stirring their solutions in water at 23° C. for 24 hours.

[0183] A second flotation test was then performed at pH 9.5 using the resulting hydrolyzed frother.

[0184] Table 3. Flotation test results of “cleavable” frothers after hydrolysis*

[0185]

[0186] *Floatation at pH 9.5 for 7 minutes.

[0187] It is clear from the results compiled in Tables 2 and 3 that blowing agents 2 and 3, which behaved like blended glycol ethers prior to hydrolysis (see Table 2), behaved more like MIBC after hydrolysis (see Table 3).

[0188] Without being bound by any theory, it is assumed that the ester functionalities of MIBC glycolate and foaming agents 1 to 3 are hydrolyzed to give hydrolyzate and MIBC, and surprisingly it is the mixture thereof that behaves like MIBC.

[0189] The inventors have shown that compositions of blowing agents according to the present invention can unexpectedly behave as strong blowing agents at a given pH (with some performance exceeding those of well-known strong blowing agents such as blended glycol ethers) while behaving as less strong or even weak blowing agents (with some performance exceeding those of well-known weaker blowing agents such as MIBC) after or during a stage at a higher pH.

[0190] The inventors have shown that the foamer composition according to the invention initially behaves as a strong foamer and hydrolyzes to give a hydrolysate and one or more alcohols, the foaming behavior of which is adopted after the hydrolysis.

[0191] Furthermore, the inventors have shown that these compositions are advantageous in terms of safety in storage, transportation or handling compared to other blowing agents such as MIBC, at least due to the higher flash point.

Claims

1. A composition for use in recovering valuable minerals from ores and other raw materials by froth flotation, characterized in that The composition comprises at least one compound having formula (I): (I) in: A represents an alkanediyl group selected from the list consisting of -CH2-, -CH2-CH2-, -CH2-CH2-CH2-, -CH2-CH2-CH2-CH2-, -CH2-CH2-CH2-CH2-CH2-, -CH2-CH2-CH2-CH2-CH2- and -CH(CH3)- and -C(CH3)2-, B, which may be the same or different at each occurrence, represents an alkanediyl group selected from the group consisting of -CH2-CH2-, -CH2-CH(CH3)-, -CH(CH3)-CH2- and -CH2-CH2-CH2-CH2-, R stands for H, n is an integer ≥ 1 and ≤ 100, and R1 is selected from the list consisting of: , , , , , , and .

2. The use according to claim 1, wherein In the composition, R1 is selected from the following list: 、 、 、 , and .

3. The use according to claim 1, wherein In the composition, n is selected from 1 to 10.

4. The use according to claim 3, wherein In the composition, n is selected from 1 to 6.

5. The use according to claim 4, wherein In the composition, n is selected from 1 to 4.

6. The use according to any one of claims 1 to 5, wherein The composition further comprises: at least one compound selected from the group consisting of: a foaming agent, a collector, water, a compatibilizer, a defoaming agent, a dispersant, a pH adjuster, a rheology adjuster, an activator, an inhibitor, a lubricant, an antiscalant and a preservative.

7. The use according to any one of claims 1 to 5, wherein The composition further comprises a surfactant.

8. A froth flotation process for recovering valuable minerals from ores and other raw materials, the process comprising adding to the ores and other raw materials a composition as defined in any one of claims 1 to 7.

9. The froth flotation method according to claim 8, wherein: Valuable minerals are sulfide minerals, non-sulfide minerals or native metals.

10. The froth flotation method according to claim 8, wherein: Valuable minerals are energy minerals.

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