Bis-phenyl bridged dihydroximic acid flotation collecting agent and preparation method and application thereof

Abstract

The invention belongs to the technical field of mineral processing and beneficiation reagents, and particularly relates to a double-phenyl-bridged dihydroximic acid flotation collecting agent and a preparation method and application of the double-phenyl-bridged dihydroximic acid flotation collecting agent. The general chemical formula of the biphenyl bridged dihydroximic acid flotation collecting agent is HO-NHC (= O)-Ar-O-R-O-Ar-C (= O)-NHOH; wherein Ar is an aromatic ring group of which the ortho-position is provided with carboxyl or carboxylic ester group; and R is alkylene with 1-8 carbon atoms. The collecting agent with the double-benzene-ring double-hydroximic-acid structure is expected to have higher selectivity, more stable chelation capacity and higher hydrophobicity at the same time, so that the collecting agent shows excellent collecting effect and separation efficiency in the flotation process, and the defects that an existing hydroximic acid agent is insufficient in selectivity, poor in hydrophobicity and the like are effectively overcome.

Description

Technical Field

[0001] This invention belongs to the field of mineral processing and beneficiation reagents technology, specifically relating to a bisphenyl-bridged bishydroxyoxime flotation collector, its preparation method, and its application. Background Technology

[0002] Hydroxyxamic acid collectors are widely used in mineral flotation due to their ability to form stable chelates with transition metal ions and rare earth metal ions. The hydroxyl oxygen, oxime oxygen, and nitrogen atom in the hydroxyxamic acid molecule all possess abundant lone pairs of electrons, enabling them to react with Fe... 3+ Fe 2+ RE 3+ Pb 2+ Co 2+ Ti 4+ and Sn 4+ Hydroxyxamic acid compounds form stable chelate complexes with various metal ions. This property makes them excellent in the flotation of metal ores such as rare earth minerals, ilmenite, tungsten ores, tin ores, copper oxide ores, and iron ores.

[0003] Currently, most industrially used hydroxamic acid collectors have a monohydroxamic acid structure, meaning each molecule contains only one hydroxamic acid group. Based on the different hydrophobic groups in the molecule, these collectors can be divided into two main categories: aromatic hydroxamic acids and aliphatic hydroxamic acids. Typical examples of the former include benzyl hydroxamic acid and salicylic acid, which use an aromatic ring as a hydrophobic group and have been widely used in the flotation separation of oxide minerals such as tungsten and rare earth ores. The latter, such as alkyl hydroxamic acids (e.g., octyl hydroxamic acid), use an aliphatic hydrocarbon chain as a hydrophobic end, and some studies have also explored their application in the flotation of minerals such as tungsten and tin. However, in general, traditional hydroxamic acid collectors suffer from problems such as simple structure and unimproved performance.

[0004] To address the issue of insufficient hydrophobicity in hydroxamic acid collectors, researchers have explored numerous improvements. For example, Chinese invention patent CN115228618A, concerning the application of an O-allyl salicylhydroxyxamic acid compound in metal mineral flotation, and Chinese invention patent CN115228617A, concerning a 3-allyl salicylhydroxyxamic acid compound, its preparation, and its application in metal mineral flotation, both disclose the introduction of longer hydrophobic chains or hydrophobic groups (such as alkoxy, allyl, etc.) into aromatic hydroxamic acid molecules. This has led to the development of novel collectors such as alkoxybenzylhydroxyxamic acid and allyl salicylhydroxyxamic acid, significantly enhancing molecular hydrophobicity and thus improving their collection ability for metal oxide ores.

[0005] In addition, existing technologies enhance the collecting performance by increasing the number or types of functional groups in hydroxamic acid molecules. For example, Chinese invention patents CN104888969A, CN106955790A, and CN118255701A disclose a series of modified hydroxamic acid structures containing bifunctional groups. By introducing multiple hydroxamic acid groups or other chelating / hydrophobic functional groups into the same molecule, the multi-site adsorption of the agent on the mineral surface is enhanced, further improving the collecting effect. Summary of the Invention

[0006] This invention designs a novel flotation collector based on a diphenyl ring dihydroxyoxime acid. In terms of molecular structure, a symmetrical rigid "diphenyl ring" framework is introduced, connected by appropriate bridging bonds, with each end carrying a hydroxamic acid chelating group. This "diphenyl ring-bridging-dihydroxyoxime group" molecular design significantly improves the collector's selectivity for target oxidized minerals and endows it with stronger and more stable chelating coordination ability. Simultaneously, the added aromatic ring hydrophobic group in the molecule increases the hydrophobicity imparted to the mineral surface by the reagent, promoting the binding of mineral particles and bubbles, and improving flotation efficiency. The collector with the diphenyl ring dihydroxyoxime acid structure provided by this invention is expected to simultaneously possess stronger selectivity, more stable chelating ability, and higher hydrophobicity, thus exhibiting excellent collection and separation efficiency during flotation, effectively overcoming the shortcomings of existing hydroxamic acid reagents such as insufficient selectivity and poor hydrophobicity.

[0007] The first objective of this invention is to provide a novel dihydroxyoxime-type flotation collector, which employs a molecular framework with two rigid aromatic groups, two hydroxyoxime head groups, and a flexible ether bridge structure, thereby enabling the reagent to possess both strong coordination ability and interfacial activity, thus improving the flotation separation effect of rare earth minerals and other oxide ores.

[0008] To achieve the above objectives, the present invention provides the following technical solution: A diphenyl-bridged dihydroxyoxime acid flotation collector with the general chemical formula: HO–NHC(=O)–Ar–O–R–O–Ar–C(=O)–NHOH; Wherein, Ar is an aromatic ring group with a carboxyl or carboxylic ester group in the ortho position; R is an anhydride group with 1 to 8 carbon atoms.

[0009] As a preferred embodiment, R is a propylidene group with 3 carbon atoms.

[0010] As a preferred option, its general chemical formula is: HO–NHC(=O)–C6H4–O–(CH2)3–O–C6H4–C(=O)–NHOH.

[0011] The biphenyl ring bihydroxyoxime acid flotation collector provided by this invention, compared with existing conventional benzyl hydroxamic acid collectors, introduces a symmetrical "biphenyl ring" rigid framework in its molecular structure, connected by appropriate bridging bonds, so that each end carries a hydroxamic acid chelating group. This design gives the molecule the following advantages: First, the symmetrical structure of the biphenyl ring improves the planarity and rigidity of the molecule, which helps the collector to adsorb and arrange itself in an orderly manner on the mineral surface, forming a stable and dense hydrophobic film layer, thus enhancing the hydrophobicity of the mineral particles at the molecular level. Second, because there are structurally identical hydroxamic acid groups at both ends of the molecule, during the flotation process, they can simultaneously form a bidentate chelate with a metal center on the mineral surface, or chelate two adjacent metal active sites, enhancing the stability and chelation coordination strength of the collector-mineral bond. The bridging rigid links can also position the two hydroxamic groups at a suitable spatial distance, which is beneficial for matching the lattice spacing of metal ions on the surface of certain oxidized minerals, improving the recognition ability and selectivity for specific minerals.

[0012] The second objective of this invention is to provide a method for preparing a novel diaromatic dihydroxyoxime acid type flotation collector. This method has advantages such as low cost, simple operation, mild conditions, high reaction yield, and few by-products, and can be produced on a large scale.

[0013] A method for preparing a diphenyl-bridged dihydroxyoxime acid flotation collector includes the following steps: (1) React hydroxy aromatic carboxylic acid esters with dihalogenated alkanes under alkaline conditions to obtain diester diether intermediates; (2) The diester-diether intermediate reacts with hydroxylamine or its salt to obtain a bisphenyl-bridged bishydroxyoxime flotation collector.

[0014] The principle of this invention is as follows: The synthesis of the bishydroxyoxime acid collector is based on a series of organic nucleophilic and substitution reactions, with the core including two major steps: ether bridging reaction and hydroxyoximation reaction. First, the hydroxy aromatic carboxylic acid ester molecule is etherified and bridged through an O-alkylation reaction; then, the ester group is converted into a hydroxyoxime acid group through a hydroxyoximeation reaction. Specifically, in step (1), the aromatic phenolic hydroxyl group generates the corresponding phenolic anion under basic conditions, which undergoes active nucleophilic substitution of the haloalkane to form an ether-linked diester intermediate. Next, in step (2), hydroxylamine, as a nucleophile, attacks the carbonyl carbon of the ester group, undergoing nucleophilic addition to form a tetrahedral intermediate. Subsequently, the intermediate undergoes intramolecular elimination, removing a small molecule alcohol (such as methanol) to generate the target hydroxyoxime acid salt. This hydroxyoximeation reaction is essentially an acyl substitution reaction: the nucleophilic attack of the ester carbonyl group by hydroxylamine and the subsequent elimination of the leaving group together complete the key structural transformation from the ester group to the hydroxyoxime acid group.

[0015] As a preferred embodiment, the molar ratio of the hydroxy aromatic carboxylic acid ester to the dihalogenated alkane in step (1) is 1:0.25-2, the reaction temperature is 20-130℃, and the reaction time is 0.5-12h; the acid-binding agent used in the reaction is sodium ethoxide or potassium carbonate, and the solvent is any one of methanol, ethanol, acetone or DMF.

[0016] As a preferred embodiment, the molar ratio of the hydroxy aromatic carboxylic acid ester to the dihalogenated alkane in step (1) is 1:0.4-1, the acid-binding agent is potassium carbonate, and the solvent is DMF.

[0017] As a preferred embodiment, the molar ratio of the diester diether intermediate to hydroxylamine or its salt in step (2) is 1:0.25-2, the reaction temperature is 20-80℃, and the reaction time is 0.5-12h.

[0018] As a preferred embodiment, the molar ratio of the diester diether intermediate to hydroxylamine or its salt in step (2) is 1:0.4 to 1.

[0019] As a preferred embodiment, the hydroxy aromatic carboxylic acid ester includes any one of methyl phthalate, methyl 3-hydroxybenzoate, methyl 4-hydroxybenzoate, methyl polyhydroxybenzoate, and methyl amino-hydroxybenzoate. As a preferred embodiment, the dihalogenated alkane includes any one of 1,4-dibromopropane, dibromomethane, dibromoethane, dibromobutane, dichloroethane, and dichloromethane; As a preferred embodiment, the hydroxylamine or its salt includes any one of hydroxylamine hydrochloride, hydroxylamine sulfate, hydroxylamine phosphate, or its salt.

[0020] As a preferred embodiment, the hydroxy aromatic carboxylic acid ester is methyl o-hydroxybenzoate, the dihaloalkane is 1,4-dibromopropane, and the hydroxylamine is hydroxylamine hydrochloride.

[0021] The third objective of this invention is to provide a novel dihydroxyoxime type flotation collector for use in the flotation of metal oxide or rare earth ores, which can better recover valuable metal minerals from oxide ores containing elements such as tungsten, tin, titanium, iron, copper, lead, and rare earth elements.

[0022] Application of a bisphenyl-bridged bishydroxyoxime acid flotation collector in the flotation of metal oxide ores, wherein the metal oxide ores are metal oxide ores containing at least one of tungsten, tin, titanium, iron, copper, lead, and rare earth elements.

[0023] As a preferred embodiment, the dosage of the diphenyl-bridged dihydroxyoxime acid flotation collector is 1–1000 g / t relative to the mass of the raw ore, and the flotation pH range is 6–10. Using the diphenyl-bridged dihydroxyoxime acid provided by this invention as a collector results in low reagent dosage, high flotation efficiency, wide applicability, and simple operation.

[0024] The working principle of the biaromatic dihydroxyoxime acid flotation collector of the present invention in the flotation process is as follows: it utilizes the chelation of the hydroxamic acid group with the active sites of metal ions on the mineral surface to form a stable chelated five-membered ring structure, which is then adsorbed onto the mineral surface by chemical adsorption. The collector molecule of the present invention contains two hydroxamic acid head groups, which can simultaneously coordinate and adsorb with multiple metal sites on the same mineral particle surface to achieve multi-site anchoring. This multidentate coordination mechanism significantly improves the binding strength and stability of the collector on the target mineral surface, thereby enhancing the collection effect on the mineral particles. The molecular design of introducing aromatic rings and flexible ether bridges improves the solubility and dispersibility of the agent in water, which is beneficial to its uniform distribution in the pulp.

[0025] The process of using the bisaromatic dihydroxyoxime acid flotation collector of the present invention for mineral flotation is as follows: after crushing, grinding and slurry preparation of the metal mineral, flotation reagents including the bisaromatic bridging dihydroxyoxime acid compound are added for flotation to obtain concentrate product and in-cell product.

[0026] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows: (1) The preparation method of bisphenyl-bridged bishydroxyoxime acid provided by the present invention uses readily available aromatic hydroxycarboxylic acid esters (or their derivatives) and α,ω-dihalo-bridgers as the main raw materials. A symmetrical bisaromatic skeleton is constructed through O-alkylation bridging reaction under alkaline conditions, and then the ester group is efficiently converted to the hydroxyoxime group by hydroxylamine oximation. The synthetic route has few reaction steps, mild conditions, simple post-processing, and strong reproducibility. The by-products are mainly inorganic salts and low molecular weight alcohols. It has the characteristics of low raw material cost, low environmental burden, and good scale-up feasibility. It is suitable for continuous preparation from laboratory scale to pilot scale.

[0027] (2) Compared with existing monohydroxyxamic acid collectors (such as benzyl hydroxyxamic acid, salicylic acid, or aliphatic hydroxyxamic acid), the bisphenyl-bridged bishydroxyxamic acid of this invention introduces two spatially synergistic hydroxyxamic acid chelating sites into the molecular structure, and achieves symmetrical construction of a dual aromatic hydrophobic framework through bridging groups, thereby simultaneously enhancing the multi-site coordination binding ability to metal active sites on the surface of oxidized minerals and the hydrophobicity of the mineral surface; based on the comprehensive effect of "bishydroxyxamic acid multidentate chelating effect + dual aromatic hydrophobic synergistic effect + bridging spatial matching effect", the present invention collects The agent can form a more stable and denser adsorption layer on the surface of target oxidized minerals (including rare earth oxides, tungsten ores, ilmenite, etc.) and achieve efficient collection of target minerals at a lower dosage. At the same time, due to the differences in the type of metal sites and hydration characteristics on the surface of target oxidized minerals and gangue minerals (such as fluorite, dolomite, barite, etc.), the collector of this invention exhibits stronger selective coordination adsorption on the surface of target minerals, while reducing non-selective adsorption on gangue minerals, thereby obtaining higher concentrate grades and better recovery rates in complex mineral systems.

[0028] (3) The bisphenyl-bridged bishydroxyxamic acid of the present invention regulates the effective spacing and orientation of the two hydroxyxamic acid head groups through the bridging group, which can achieve better geometric matching with the spacing of metal sites on the surface of different oxidized minerals. Compared with the traditional hydroxyxamic acid with a single structure, the collector of the present invention is more likely to form a "multi-point anchoring-synergistic adsorption" configuration, with higher adsorption stability and less desorption under stirring, aeration and shearing conditions, so as to maintain relatively stable collection performance and selective separation effect under the fluctuation of flotation conditions.

[0029] (4) The hydrophobic molecular skeleton of the bisphenyl-bridged bishydroxyoxime acid of the present invention is composed of two aromatic rings. Compared with the single aromatic ring or short-chain aliphatic group structure, the unit molecule makes a stronger contribution to the hydrophobicity of the mineral surface, which can reduce the dependence on oil synergists or additional collectors and reduce the complexity of the reagent system. In addition, by introducing appropriate substituents (such as alkyl, alkoxy, halogen or weakly polar groups) on the aromatic ring, the hydrophobicity and electronic effect of the collector can be further adjusted, so as to optimize the adaptability to different ore systems and improve the versatility and controllability in the flotation of oxide ores such as rare earth, tungsten, and ilmenite.

[0030] (5) The collector of the present invention is compatible with conventional pH adjusters and gangue inhibitor systems during use. In particular, it can maintain effective chelation adsorption and hydrophobicity under weakly alkaline to alkaline conditions. It is suitable for direct replacement or process upgrade of existing flotation processes in beneficiation plants. Without significantly increasing the number of process steps, it can achieve comprehensive technical effects such as reduced reagent dosage, improved concentrate quality, and stable separation indicators, thus having good industrial promotion value. Attached Figure Description

[0031] Figure 1The 1H NMR spectrum of the diphenyl-bridged dihydroxyoxime acid prepared in Example 1; Figure 2 This is a flowchart of a flotation test for an application example of the present invention; Figure 3 The figure shows the experimental results of Application Example 1. Detailed Implementation

[0032] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] Unless otherwise specified, all raw materials, reagents, instruments, and equipment used in this invention can be purchased commercially or prepared using existing methods. The solvents used are analytical grade or chemically pure, and drying is performed if necessary; the water is deionized water or purified water of equivalent grade.

[0034] Example 1 A bisphenyl-bridged bishydroxyoxime acid flotation collector, prepared by the following steps: (1) Preparation of bridged diester intermediate: Under stirring, 8.44 g (0.0555 mol) of methyl o-hydroxybenzoate, 7.67 g (0.0555 mol) of anhydrous potassium carbonate, and 120 mL of anhydrous acetone were added sequentially to a 250 mL three-necked flask. The mixture was stirred thoroughly and pre-stirred at room temperature for 0.5 h. Subsequently, 5.99 g (0.0278 mol) of 1,4-dibromopropane, a bridging agent, was added dropwise. A reflux condenser was installed, and the reaction was carried out at the reflux temperature of acetone (approximately 56 °C) for 12 h. The disappearance of the starting material spot could be monitored by thin-layer chromatography (TLC) during the reaction.

[0035] After the reaction was complete, the mixture was cooled to room temperature, filtered to remove inorganic salts, and the filter cake was washed with a small amount of acetone. The filtrates were combined and the acetone was removed by vacuum distillation. The residue was dissolved in ethyl acetate and washed successively with deionized water (2 × 50 mL) and saturated brine (1 × 50 mL). The organic phase was dried over anhydrous sodium sulfate, filtered, and concentrated under reduced pressure to obtain a pale yellow oily or solid crude product. The crude product was recrystallized from ethanol / water (v / v ratio approximately 3:1) to give a white solid bridged diester intermediate.

[0036] (2) Preparation of diphenyl-bridged dihydroxyoxime acid: Add 12.5 g (approximately 0.18 mol) of hydroxylamine hydrochloride and 60 mL of deionized water to a 500 mL three-necked flask and stir under ice bath conditions to dissolve it. Then add 7.6 g (0.19 mol) of sodium hydroxide in batches, control the temperature to not exceed 20 °C and adjust the pH of the solution to 9.0 to obtain an aqueous solution of free hydroxylamine.

[0037] Add 150 mL of anhydrous ethanol to the system to form an ethanol / water mixed solvent system. Dissolve the bridged diester intermediate (approximately 0.030 mol) (molecular structure as shown in Formula 1) in 30 mL of anhydrous ethanol, and add it dropwise to the above hydroxylamine solution. Stir the reaction at 50 °C for 10 h. After the reaction is complete, cool to room temperature, and adjust the pH of the system to 4.0 by adding 10 wt.% hydrochloric acid solution dropwise under stirring. Continue stirring for 1 h to allow the product to fully precipitate. Filter and collect the solid, wash with a small amount of cold water and cold ethanol, and dry under vacuum at 40 °C to obtain a light yellow to white solid, namely diphenyl-bridged dihydroxyoxime acid (molecular structure as shown in Formula 2, 1H NMR spectrum shown in Formula 2). Figure 1 The product can be further purified by recrystallization using an ethanol / water system to meet the purity requirement of ≥90%.

[0038]

[0039] Formula 1: Bridged diester intermediate

[0040] Formula 2: Diphenyl-bridged dihydroxyoxime acid Flotation performance evaluation: using methods such as Figure 2 The micro-flotation test flowchart shown is used to conduct the flotation performance test of the present invention.

[0041] Using benzoyl hydroxamic acid, salicylic acid, and octyl hydroxamic acid, commonly used in this field, as the control group collectors, and the bisphenyl-bridged bishydroxamic acid prepared in Example 1 as the experimental group collector, flotation efficiency experiments were conducted on bastnaesite, wolframite, and ilmenite, as well as separation efficiency experiments on bastnaesite and barite. Details are as follows: Application Example 1 Biphenyl-bridged bis(hydroxyxamic acid) and benzyl(hydroxyxamic acid) were used as collectors for the flotation of bastnaesite: Add 2×10⁻⁶ diphenyl-bridged hydroxamic acid and benzohydroxyxamic acid respectively. -5 The flotation machine speed was 1900 r / min, the flotation rate was mol / L, the frother MIBC dosage was 10 μL / L, the flotation machine speed was 1900 r / min, and the fluorocarbon cerium ore with a particle size of 200-400 mesh was floated for 3 min. During the experiment, NaOH or HCl solution was used as pH adjuster to adjust the pH of the pulp. The flotation experiment results are as follows Figure 3As shown in the figure, the recovery rate of fluorocarbon cerium ore using benzyl hydroxamic acid as a collector is no more than 25%, with a maximum of only 24.18%; the flotation recovery rate of fluorocarbon cerium ore using diphenyl-bridged dihydroxyxamic acid as a collector is much higher than that of benzyl hydroxamic acid, and reaches 97.81% when the pH of the flotation pulp is 10.9.

[0042] Application Example 2 Biphenyl-bridged bis(hydroxyoxime) acid and salicylic acid were used as collectors for the flotation of bastnaesite: Diphenyl-bridged hydroxamic acid and salicylic acid were added separately, each at a dosage of 2×10⁻⁶. -5 The concentration was mol / L, the pH was its natural pH, the amount of frother MIBC was 10 μL / L, the flotation machine speed was 1900 r / min, and the fluorocarbon cerium ore sample with a particle size of 200-400 mesh was floated for 3 min. The flotation recovery rate of salicylhydroxyxamic acid for fluorocarbon cerium ore was only 20.71%; while the flotation recovery rate of diphenyl-bridged dihydroxyxamic acid for fluorocarbon cerium ore was 89.67%.

[0043] Application Example 3 Biphenyl-bridged bis(hydroxyoxime) acid and octyl(hydroxyoxime) acid were used as collectors for the flotation of bastnaesite: Diphenyl-bridged hydroxamic acid and octyl hydroxamic acid were added separately, each at a dosage of 2 × 10⁻⁶. -5 The concentration was mol / L, the pH was its natural pH, the amount of frother MIBC was 10 μL / L, the flotation machine speed was 1900 r / min, and the fluorocarbon cerium ore sample with a particle size of 200-400 mesh was floated for 3 min. Octyl hydroxamic acid had a flotation recovery rate of only 50.63% for bastnaesite; while diphenyl-bridged dihydroxamic acid had a flotation recovery rate of 89.67% for bastnaesite.

[0044] Application Example 4 Biphenyl-bridged bis(hydroxyxamic acid) and benzo(hydroxyxamic acid) were used as collectors for the flotation of wolframite. Add 2×10⁻⁶ diphenyl-bridged hydroxamic acid and benzohydroxyxamic acid respectively. -5 The concentration was mol / L, the pH was its natural pH, the amount of frother MIBC was 10 μL / L, the flotation machine speed was 1900 r / min, and the wolframite sample with a particle size of 200-400 mesh was floated for 3 min. The flotation recovery rate of benzohydroxyxamic acid for wolframite was only 10.35%; while the flotation recovery rate of diphenyl-bridged dihydroxyxamic acid for wolframite was 86.73%.

[0045] Application Example 5 Biphenyl-bridged bis(hydroxyxamic acid) and benzyl(hydroxyxamic acid) were used as collectors for the flotation of ilmenite: Add 2×10⁻⁶ diphenyl-bridged hydroxamic acid and benzohydroxyxamic acid respectively. -5 The concentration was mol / L, the pH was its natural pH, the amount of frother MIBC was 10 μL / L, the flotation machine speed was 1900 r / min, and the ilmenite sample with a particle size of 200-400 mesh was floated for 3 min. The flotation recovery rate of ilmenite was only 20.57%; the flotation recovery rate of ilmenite by diphenyl-bridged dihydroxyoxime was 90.26%.

[0046] Application Example 6 Biphenyl-bridged dihydroxamic acid, benzyl hydroxamic acid, octyl hydroxamic acid, and salicylic acid were used as collectors for flotation separation of bastnaesite and barite. Diphenyl-bridged hydroxamic acid, benzohydroxyxamic acid, octylhydroxyxamic acid, and salicylic acid were added respectively, each at a dosage of 2×10. -5 The flotation parameters were: mol / L, pH was the natural pH, MIBC frother was used at a rate of 10 μL / L, flotation machine speed was 1900 r / min, and artificial mixed mineral samples with a particle size of 200-400 mesh (mass ratio of bastnaesite to barite was 1:1) were floated for 3 min. Benzyl hydroxamic acid beneficiation results: The REO grade of the concentrate product was 68.31%, and the recovery rate was only 30.56%; Salicylic acid beneficiation results: The REO grade of the concentrate product was 65.39%, and the recovery rate was 87.43%. Octyl hydroxamic acid beneficiation results: The REO grade of the concentrate product was 64.97%, and the recovery rate was 92.16%. Results of beneficiation of diphenyl-bridged dihydroxyoxime acid: The REO grade of the concentrate product was 70.72%, and the recovery rate was 92.39%.

[0047] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A bisphenyl-bridged bishydroxyoxime acid flotation collector, characterized in that, Its general chemical formula is: HO–NHC(=O)–Ar–O–R–O–Ar–C(=O)–NHOH; Wherein, Ar is an aromatic ring group with a carboxyl or carboxylic ester group in the ortho position; R is an anhydride group with 1 to 8 carbon atoms.

2. The bisphenyl-bridged bishydroxyoxime acid flotation collector according to claim 1, characterized in that, R is a propylene group with 3 carbon atoms.

3. The bisphenyl-bridged bishydroxyoxime acid flotation collector according to claim 1, characterized in that, Its general chemical formula is: HO–NHC(=O)–C6H4–O–(CH2)3–O–C6H4–C(=O)–NHOH.

4. A method for preparing the diphenyl-bridged dihydroxyoxime acid flotation collector as described in any one of claims 1 to 3, characterized in that, Includes the following steps: (1) React hydroxy aromatic carboxylic acid esters with dihalogenated alkanes under alkaline conditions to obtain diester diether intermediates; (2) The diester-diether intermediate reacts with hydroxylamine or its salt to obtain a bisphenyl-bridged bishydroxyoxime flotation collector.

5. The preparation method according to claim 4, characterized in that, In step (1), the molar ratio of the hydroxy aromatic carboxylic acid ester to the dihalogenated alkane is 1:0.25-2, the reaction temperature is 20-130℃, and the reaction time is 0.5-12h. The acid-binding agent used in the reaction is sodium ethoxide or potassium carbonate, and the solvent is any one of methanol, ethanol, acetone or DMF.

6. The preparation method according to claim 4, characterized in that, In step (2), the molar ratio of the diester diether intermediate to hydroxylamine or its salt is 1:0.25-2, the reaction temperature is 20-80℃, and the reaction time is 0.5-12h.

7. The preparation method according to claim 4, characterized in that, The hydroxy aromatic carboxylic acid esters include any one of o-hydroxybenzoate, methyl 3-hydroxybenzoate, methyl 4-hydroxybenzoate, polyhydroxybenzoate, amino-hydroxybenzoate, and halogen-hydroxybenzoate. The dihalogenated alkanes include any one of 1,4-dibromopropane, dibromomethane, dibromoethane, dibromobutane, dichloroethane, and dichloromethane; The hydroxylamine or its salts include any one of hydroxylamine hydrochloride, hydroxylamine sulfate, hydroxylamine phosphate, or their salts.

8. The preparation method according to claim 7, characterized in that, The hydroxy aromatic carboxylic acid ester is methyl o-hydroxybenzoate, the dihalogenated alkane is 1,4-dibromopropane, and the hydroxylamine or its salt is hydroxylamine hydrochloride.

9. The application of the diphenyl-bridged dihydroxyoxime acid flotation collector as described in any one of claims 1 to 3, characterized in that, It is applied to the flotation of metal oxide ores, wherein the metal oxide ores are metal oxide ores containing at least one of tungsten, tin, titanium, iron, copper, lead, and rare earth elements.

10. The application according to claim 9, characterized in that, The dosage of the diphenyl-bridged dihydroxyoxime flotation collector is 1–1000 g / t relative to the mass of the raw ore, and the flotation pH range is 6–10.

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