A method for preparing a flotation collector, a flotation collector and a method for flotation of oxidized minerals.

Abstract

This invention relates to a method for preparing a flotation collector, a flotation collector, and a flotation method for oxidized minerals, belonging to the field of mineral processing technology. It solves the problems of low flotation recovery rates, high temperature dependence, high energy consumption, and environmental pollution associated with existing collectors for oxidized minerals. The flotation collector prepared by the method described above has high polarity, significantly enhancing the adsorption between it and functional groups on the mineral surface, thus improving the mineral flotation recovery rate. Under low-temperature conditions, it exhibits good water solubility and dispersibility, contributing to improved mineral recovery rates at low temperatures. Combined with the appropriate carbon chain length of the collector molecule, flotation can be achieved over a wide flotation temperature range, reducing the impact of temperature on mineral flotation and achieving energy saving and carbon reduction in the flotation method. Furthermore, the collector molecule contains two carboxyl groups, readily chelating with metal cations to achieve selective collection of metal ions, making it suitable for flotation under various water quality conditions.

Description

Technical Field

[0001] This invention relates to the field of mineral processing technology, and in particular to a method for preparing a flotation collector, a flotation collector, and a method for flotation of oxidized minerals. Background Technology

[0002] Currently, the flotation method for oxide minerals mainly uses fatty acid collectors, which have the advantages of being economical, efficient, and requiring small amounts.

[0003] There are two typical methods for the flotation of oxidized minerals: one is to directly float the oxidized minerals using cationic amine collectors, such as primary amines and their corresponding acetic acid or chlorine derivatives. However, these cationic amine collectors can cause certain environmental hazards and have problems such as high foam viscosity and difficulty in defoaming during use. The other method is to first activate the oxidized minerals with polyvalent metal ions (such as calcium and magnesium ions) and then float them with anionic collectors, such as fatty acids, oxidized paraffin soaps, and talc oil. Due to the wide availability and low cost of long-chain fatty acids and their salts, they are widely used industrially for oxidized mineral flotation. However, the solubility and dispersibility of these collectors are greatly affected by temperature and are very sensitive to the temperature of the pulp. Under low-temperature conditions (below 20°C), their water solubility and dispersibility are poor, affecting the flotation recovery rate. When used under low-temperature conditions, it is often necessary to heat the pulp to improve its collecting capacity, which increases the energy consumption and cost of the flotation process and is not conducive to environmental protection and energy conservation and carbon reduction.

[0004] In response to the current problems encountered in the flotation of oxidized minerals, there is an urgent need for a green and environmentally friendly flotation collector that is not sensitive to temperature and its preparation method. This collector should not only have a high mineral flotation recovery rate, but also improve the collection efficiency at low temperatures, achieve flotation over a wide temperature range, save energy and reduce carbon emissions, and lower energy consumption. Summary of the Invention

[0005] Based on the above analysis, the embodiments of the present invention aim to provide a method for preparing a flotation collector, a flotation collector and a flotation method for oxidized minerals, in order to solve at least one of the problems of existing collectors for the flotation of oxidized minerals, such as low recovery rate, large temperature influence, high energy consumption and environmental pollution.

[0006] In a first aspect, embodiments of the present invention provide a method for preparing a collector, the method comprising:

[0007] (1) React fatty acids with halogenating reagents to prepare α-halogenated fatty acids;

[0008] (2) Dissolve lysine in an alkaline solution, then add the α-halo fatty acid, and react the α-halo fatty acid with lysine.

[0009] The fatty acid is one or more of decanoic acid, dodecyl acid, and tetradecyl acid.

[0010] Furthermore, in step (2), the molar ratio of lysine to the solute in the alkaline solution is 1:(0.4-0.6).

[0011] Furthermore, in step (2), the molar ratio of the α-halofatty acid to the lysine is 1:(1.1-1.2).

[0012] Furthermore, in step (2), the reaction temperature is 95-110℃ and the time is 4-6h.

[0013] Secondly, embodiments of the present invention provide a flotation collector, which is obtained by the preparation method described in the first aspect.

[0014] Thirdly, embodiments of the present invention provide a flotation method for oxidized minerals, the flotation method comprising:

[0015] (1) Prepare the ore sample to be processed into a slurry;

[0016] (2) Adjust the pH of the slurry and add the flotation collector described in the second aspect;

[0017] (3) Aeration flotation.

[0018] Furthermore, in step (2), the pH of the slurry is 7-14, and the concentration of the flotation collector is 40-100 mg / L.

[0019] Furthermore, in step (3), the temperature of the aeration flotation is 10-40℃ and the time is 2-3 minutes.

[0020] Furthermore, step (2) also includes adding an activator to the slurry.

[0021] Furthermore, the mineral is an oxide mineral, preferably selected from one or more of quartz, iron ore, calcite, apatite, fluorite, and scheelite.

[0022] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0023] 1. The process for preparing the flotation collector of this invention is simple, the preparation method of α-halo fatty acids is mature and easy to obtain, the process requirements for the reaction of the α-halo fatty acids with lysine are low and easy to implement, the use of lysine to prepare the flotation collector makes the waste liquid after the reaction easy to treat, reducing the energy consumption and cost of preparation; and the obtained amino acid collector has low toxicity, low volatility and biodegradability, which is environmentally friendly.

[0024] 2. The flotation collector prepared by the method of this invention contains two carboxyl groups and two amino groups. Compared with traditional fatty acid collectors, it has stronger polarity and is more likely to form hydrogen bonds or electrostatic interactions with the mineral surface, thus adsorbing onto the mineral surface. This enhanced polarity improves the collector's solubility and dispersibility in water, allowing it to dissolve well in water at low temperatures without heating, ensuring flotation efficiency under low-temperature conditions. Combined with the collector's suitable carbon chain length, the collector can achieve flotation over a wider temperature range, reducing the impact of temperature on mineral flotation and achieving energy saving and carbon reduction in the flotation method. Figure 6 It can be seen that, compared with the flotation method using sodium oleate as the traditional collector, the flotation method of the present invention, using 2-[(5-amino-5-carboxymethyl)amino]lauric acid as the collector, has good flotation efficiency for quartz ore in the temperature range of 10-40℃.

[0025] 3. The flotation collector prepared by the method of the present invention contains carboxyl and amino functional groups, which can easily chelate with metal cations. The metal ions become active sites for flotation. Therefore, when applied to hard water environments rich in metal cations, it not only enhances the binding strength between the collector and the mineral surface and improves the collection efficiency of minerals, but also achieves selective collection of metal ions.

[0026] 4. When using the collector prepared by this invention, the collector can be well dissolved and dispersed in water at low temperatures without heating. This reduces the amount of collector used while ensuring the flotation efficiency of minerals under low-temperature conditions, achieving energy saving and carbon reduction, reducing energy consumption, and mitigating the environmental impact of collector usage.

[0027] 5. The collector prepared by this invention has a good flotation effect on high-alkali pulp, from Figure 4 and Figure 7 It can be seen that the method of the present invention exhibits good mineral collection efficiency in a highly alkaline environment.

[0028] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0029] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0030] Figure 1This is a schematic diagram of the process for preparing the collector 2-[(5-amino-5-carboxymethyl)amino]lauric acid in Example 1;

[0031] Figure 2 The infrared spectral characterization results are as follows for the collector 2-[(5-amino-5-carboxymethyl)amino]lauric acid prepared in Example 1;

[0032] Figure 3 The high-resolution mass spectrometry characterization results of the collector 2-[(5-amino-5-carboxymethyl)amino]lauric acid prepared in Example 1 are shown below.

[0033] Figure 4 The graph shows the change in quartz flotation recovery with pH at 25℃ when the collectors are 2-[(5-amino-5-carboxymethyl)amino]lauric acid (ADA) and sodium oleate (NaOL).

[0034] Figure 5 The graph shows the change in quartz flotation recovery rate with the amount of collector added when the collectors are 2-[(5-amino-5-carboxymethyl)amino]lauric acid (ADA) and sodium oleate (NaOL) at 25℃.

[0035] Figure 6 The graph shows the change in quartz flotation recovery rate with temperature when the pulp pH is 11.5 and the collectors are 2-[(5-amino-5-carboxymethyl)amino]lauric acid (ADA) and sodium oleate (NaOL).

[0036] Figure 7 The graph shows the change in quartz flotation recovery rate with pH at 10℃ when the collectors are 2-[(5-amino-5-carboxymethyl)amino]lauric acid (ADA) and sodium oleate (NaOL).

[0037] Figure 8 The graph shows the change in quartz flotation recovery rate with the amount of collector added when the collectors are 2-[(5-amino-5-carboxymethyl)amino]lauric acid (ADA) and sodium oleate (NaOL) at 10℃. Detailed Implementation

[0038] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0039] Currently, the flotation of oxidized minerals mainly uses anionic fatty acid collectors. The solubility and dispersibility of traditional fatty acid collectors are significantly affected by temperature, being highly sensitive to pulp temperature. At low temperatures (below 20°C), both water solubility and dispersibility are poor, impacting flotation recovery rates. Under low-temperature conditions, the pulp often needs to be heated to improve its collecting capacity, which increases energy consumption and cost in the flotation process, hindering energy conservation and carbon reduction. Furthermore, traditional fatty acid collectors pose certain environmental hazards during use.

[0040] Anionic and cationic collectors are heteropolar organic compounds that contain both anionic and cationic groups in their molecules. Most anionic and cationic collectors have good solubility in water and can maintain good activity at low temperatures. They undergo various adsorption mechanisms with mineral surfaces, such as electrostatic adsorption, chemical adsorption, and chelation. They have high selectivity and are suitable for flotation under various water quality conditions.

[0041] Anionic and cationic collectors are prepared through one-step or multi-step chemical reactions, directly introducing anionic and cationic groups into the same molecule. This method requires precise control of reaction conditions and reactant ratios to ensure product purity and performance. Currently, methods for preparing anionic and cationic collectors suffer from drawbacks such as overly complex preparation processes, poor product selectivity and stability, environmental unfriendliness, and high energy consumption and cost. When researching and developing novel anionic and cationic collectors, these drawbacks must be fully considered, and solutions must be sought to improve their performance and application effectiveness.

[0042] Therefore, the present invention provides a method for preparing a collector, the method comprising:

[0043] (1) React fatty acids with halogenating reagents to prepare α-halogenated fatty acids;

[0044] (2) Dissolve lysine in an alkaline solution, then add the α-halo fatty acid, and react the α-halo fatty acid with lysine.

[0045] The fatty acid is one or more of decanoic acid, dodecyl acid, and tetradecyl acid.

[0046] The reagent used in this invention to halogenate the fatty acid can be one of liquid bromine, N-bromosuccinimide, chlorine, or N-chlorosuccinimide. Different halogenating reagents require different reaction conditions with the fatty acid, and the ease of separating the product and treating the waste liquid after the reaction also varies.

[0047] To simplify the process, improve the selectivity of α-halofatty acids, and facilitate product separation, this invention preferably employs liquid bromine via the Hell-Volhard-Zelinsky (HVZ) method to bromine fatty acids, yielding α-bromofatty acids. Under the action of a catalyst, the α-hydrogen of the fatty acid is replaced by bromine to generate α-bromofatty acids. Using phosphorus trichloride or / and phosphorus tribromide as a catalyst can promote the conversion of carboxylic acids, thereby generating α-bromofatty acids through nucleophilic substitution reactions. However, excessive catalyst can lead to side reactions. Through multiple experiments, it was found that a catalyst mass of 3–5% of the fatty acid mass results in higher reaction efficiency.

[0048] To improve the yield of α-bromofatty acids, the molar ratio of the fatty acid to liquid bromine is 1:(1.05-1.1). A slight excess of bromine ensures that the fatty acid reacts fully to form a monobromoacid, but the amount of bromine added should not be too large, otherwise side reactions will occur, and it will also be detrimental to the removal of residual liquid bromine in subsequent steps.

[0049] Specifically, in order to improve reaction efficiency and based on the reaction mechanism of the HVZ method, step (1) can be subdivided into the following two steps:

[0050] (a) The fatty acid is heated until completely melted, and the heating is continued while a catalyst is added, the mixture is stirred and reacted.

[0051] (b) Further raise the temperature of the reaction system in step (a) to a certain temperature, add liquid bromine, and continue stirring to allow the bromine to react fully.

[0052] Specifically, in step (a), the fatty acid is heated to achieve complete melting, and the heating time is controlled to ensure complete melting of the fatty acid. According to a preferred embodiment of the present invention, the temperature for melting dodecyl acid is 75-95°C, more preferably 75°C.

[0053] Specifically, in step (a), the temperature after further heating is the temperature at which the fatty acid is converted into a haloenol in the presence of a catalyst. According to a preferred embodiment of the present invention, when the fatty acid is dodecyl acid, the temperature after further heating can be controlled at 85-95°C, preferably 85°C.

[0054] Specifically, in step (b), the addition of bromine requires a higher reaction temperature and a longer reaction time. Too low a reaction temperature or too short a reaction time is detrimental to increasing the yield of the reactants, while too high a temperature leads to the elimination of hydrogen bromide from the product, generating α,β-unsaturated carboxylic acids, which also reduces the yield of α-bromofatty acids. Too long a reaction time increases energy consumption. Therefore, the temperature is 95–105°C, and the reaction time is controlled at 5 hours or more, preferably 4–6 hours.

[0055] This invention also includes a step of purifying the α-bromofatty acid obtained in step (1), which is actually removing unreacted liquid bromine and neutralizing the small amount of residual bromine in the reaction system. Specifically, the remaining liquid bromine in the container is extracted using a vacuum pump. The pumping is stopped when the reactants turn pale yellow. A certain amount of sodium sulfite solution is added to neutralize the unreacted liquid bromine. Pure water is added to the reaction solution, and the solution is transferred to a separatory funnel to separate the lower aqueous layer and the upper organic liquid layer, yielding a pale yellow or milky white liquid, which is the α-bromofatty acid. In practice, other substances can also be used to neutralize the liquid bromine, as long as they can neutralize it without producing other harmful substances.

[0056] The acylation reaction between α-halofatty acids and lysine is irreversible, generating hydrogen halides. These hydrogen halides cause amines to form salts, making it difficult for α-halofatty acids and lysine to undergo further acylation. Therefore, the reaction needs to be carried out in the presence of an alkaline reagent. Such alkaline reagents neutralize the hydrogen halides and do not affect the acylation reaction described in this invention, such as sodium hydroxide, sodium carbonate, sodium bicarbonate, and calcium hydroxide, to ensure that lysine can react fully.

[0057] Specifically, in order to improve reaction efficiency, step (2) of the collector preparation method of the present invention specifically includes: dissolving lysine in an alkaline solution, adding the α-halofatty acid obtained in step (1), and reacting; wherein the alkaline solution is at least one of sodium hydroxide aqueous solution, potassium hydroxide aqueous solution, sodium bicarbonate aqueous solution, sodium carbonate aqueous solution, and calcium hydroxide aqueous solution.

[0058] Although the basic reagent can promote the acylation reaction between α-halofatty acids and lysine by neutralizing the generated hydrogen halide, the stronger the basicity, the more easily the α-halofatty acids undergo hydrolysis, generating the byproduct α-hydroxydodecanoic acid, which is not conducive to the acylation reaction of this invention. Therefore, this invention requires limiting the amount of basic reagent added.

[0059] Specifically, the molar ratio of lysine to solute in the alkaline solution is 1:(0.4-0.6).

[0060] In step (2) of this invention, the molar ratio of the halogenated fatty acid to lysine is 1:(1.1-1.2). A slight excess of lysine can ensure that the bromoalkyl acid reacts fully, but the amount added should not be too much, otherwise it will not be conducive to the subsequent product purification.

[0061] In order to ensure the smooth progress of the reaction and obtain a high-quality product, step (2) of this invention needs to be carried out within an appropriate temperature range.

[0062] Specifically, the reaction in step (2) is carried out at a temperature of 95–110°C for 4–6 hours. If the temperature is too high, side reactions may occur in the reaction system, such as the formation of α,β-unsaturated carboxylic acids, reducing the yield and purity of the target product; halogenated fatty acids are unstable at high temperatures and easily decompose, thereby reducing the yield of the target product. According to a preferred embodiment of the present invention, the reaction in step (2) is carried out at a temperature of 95°C for 5 hours.

[0063] The chemical reaction process for preparing 2-[(5-amino-5-carboxymethyl)amino]lauric acid (ADA) using dodecanoic acid and lysine as raw materials in this invention is as follows: Figure 1 As shown. When decane or tetradecanoic acid is used to react with lysine, the synthesis method of α-halododecanoic acid and its acylation reaction with lysine are also applicable due to the structural and property similarities of fatty acids with different carbon chain lengths; however, due to the change in carbon chain length, some reaction conditions need to be adjusted in order to improve reaction efficiency, mainly the reaction temperature, which has a significant impact on the reaction.

[0064] The present invention also includes a step of purifying the product obtained in step (2), specifically: the reaction product is transferred into a separatory funnel, water is added and extracted three times to obtain a light yellow product, and the excess water is removed by atmospheric distillation at 60-90℃ for 8-12 hours. The by-product halide generated during the preparation process is easily soluble in water. The halide generated is removed by extraction, and then dried to obtain a pure final product.

[0065] The present invention also provides a flotation collector, which is obtained according to the preparation method described in the first aspect.

[0066] The flotation collector is a compound represented by formula (1):

[0067] Where n = 7, 9 or 11.

[0068] Compared with the prior art, the present invention provides an amino acid collector as shown in formula (1), which contains two carboxyl groups and two amino groups. It has strong polarity and can not only form hydrogen bonds or electrostatic interactions with the mineral surface and adsorb onto the mineral surface, but also improves its solubility and dispersibility in water. It can dissolve well in water without heating at low temperatures, ensuring flotation performance under low temperature conditions (less than 20°C). With the appropriate carbon chain length of the collector, the collector can achieve flotation in a wide range of flotation temperatures.

[0069] When the collector is 2-[(5-amino-5-carboxymethyl)amino]lauric acid, from Figure 6It can be seen that when the ADA concentration is 80 mg / L, it has a good flotation effect on quartz in the range of 10 to 40℃, and the quartz recovery rate is 80-95%.

[0070] The flotation collector of this invention contains carboxyl and amino functional groups, which readily chelate with metal cations. The metal ions become active sites for flotation. Therefore, when applied to hard water environments rich in metal cations, it can not only achieve selective collection of metal ions, but also enhance the binding strength between the collector and the mineral surface, thus promoting mineral flotation.

[0071] The nonpolar group of the amino acid-based collector in this invention is a hydrocarbon group, which has hydrophobic properties. The hydrocarbon group of the collector adsorbed on the mineral surface enhances the hydrophobicity of the mineral surface, making it easier for mineral particles to be captured by bubbles and rise to the water surface. Within a certain range, the carbon chain length of the hydrocarbon group increases, and the collection effect of fatty acids improves with increasing carbon chain length. However, this effect is not unlimited; the increase in carbon chain length should be within a suitable range, which in this invention is between C10 and C14. If the carbon chain length exceeds this range, although the hydrophobicity of the collector continues to increase, the solubility will decrease, thus weakening the collection ability.

[0072] The flotation collector of this invention can dissolve well in water at low temperatures without heating, ensuring flotation capability under low-temperature conditions, achieving energy saving and carbon reduction, and reducing energy consumption; the preparation process of the flotation collector of this invention uses lysine, which is environmentally friendly and requires no post-treatment; the obtained amino acid collector has low toxicity, low volatility and biodegradability, and is environmentally friendly.

[0073] According to a preferred embodiment of the present invention, the collector is 2-[(5-amino-5-carboxymethyl)amino]lauric acid (ADA), with the chemical structure shown in formula (2):

[0074]

[0075] According to a preferred embodiment of the present invention, the collector is 2-[(5-amino-5-carboxymethyl)amino]tetradecanoic acid, having the chemical structure shown in formula (3):

[0076]

[0077] According to a preferred embodiment of the present invention, the collector is 2-[(5-amino-5-carboxymethyl)amino]decanoic acid, having the chemical structure shown in formula (4):

[0078]

[0079] The present invention characterizes the chemical structure of the collector using infrared spectroscopy, mass spectrometry and other techniques.

[0080] The present invention also provides a flotation method for oxidized minerals, the flotation method comprising:

[0081] (1) Prepare the ore sample to be processed into a slurry;

[0082] (2) Adjust the pH of the slurry and add the collector described in the second aspect;

[0083] (3) Aeration flotation.

[0084] Preferably, in step (1), the mass concentration of the mineral sample in the slurry after slurry preparation is 5-10%. The lower the mass concentration, the better the flotation effect; however, it should not be reduced indefinitely, as this will lead to increased production costs and reduced production efficiency.

[0085] Preferably, the particle size of the mineral sample in the slurry of the present invention is 38-74 μm. If the particle size of the mineral sample is too large, it will reduce the contact area between the ore and the reagent, slow down the flotation speed, or even make it impossible to float the target mineral. If the particle size of the mineral sample is too small, it will increase the amount of reagent used, increase the flotation cost, and may also cause mud formation, reducing the flotation performance of the ore.

[0086] The pH value of the slurry has a significant impact on the flotation performance of the collector. Under different pH conditions, the solubility, dispersibility, and interaction with the mineral surface of the collector will change, thereby affecting the flotation effect. Therefore, in step (2), the pH of the slurry is adjusted using acid or alkali to adapt to the flotation of minerals by different collectors in different slurries in this invention.

[0087] According to a preferred embodiment of the present invention, when 2-[(5-amino-5-carboxymethyl)amino]lauric acid (ADA) is used as the collector for quartz flotation, the pH of the pulp is adjusted to neutral or alkaline, specifically 7-14, preferably 10-13, which is beneficial for the collection of quartz by the ADA collector. Quartz is a silicon oxide, and under neutral or alkaline conditions, its surface carries a negative charge. The added amino acid-based collector will be attracted by the electrostatic force of the quartz surface, achieving adsorption on the quartz surface. This adsorption is a type of physical adsorption.

[0088] The amount of collector used is a crucial parameter in the flotation process, directly affecting flotation efficiency and selectivity. The amount of collector needs to be adjusted based on factors such as the pH of the pulp, temperature, mineral properties, and other additives used in the flotation.

[0089] According to a preferred embodiment of the present invention, when ADA is used as the collector for quartz flotation and the pH of the pulp is adjusted to alkaline, in step (2), the concentration of the flotation collector in the pulp is 20-100 mg / L, preferably 60-90 mg / L. The adsorption of the collector on the mineral surface is closely related to the actual flotation mechanism. The flotation mechanism refers to the basic way in which the molecules or ions of the collector adsorb at the mineral-water interface, mainly including electrostatic adsorption, hydrogen bond adsorption, hemimicryl adsorption, and adsorption of the reaction products of the collector on the mineral surface. Too low a amount of collector may lead to a decrease in the recovery rate of the target mineral, while too high a amount may lead to the incorrect collection of too many gangue minerals, which also affects the recovery rate.

[0090] from Figure 5 , 8 It can be seen that, within a certain concentration range of 20-90 mg / L, the flotation recovery rate of the collector of the present invention increases significantly with the increase of the collector concentration; when the concentration reaches a certain value, the recovery rate decreases with the increase of the concentration, and the optimal concentration is 80 mg / L; when the collector concentration is too high, the flotation recovery rate decreases instead; moreover, in the flotation method of the present invention, the optimal concentration of the collector remains unchanged at 10℃ and 25℃, both being 80 mg / L, indicating that the flotation method of the present invention is not sensitive to temperature.

[0091] Flotation temperature also has a significant impact on the flotation process. The temperature of the pulp affects the solubility of the collector, the wettability of the mineral surface, the chemical reaction rate of the flotation process, the selectivity of the flotation minerals, and the selectivity of the flotation froth.

[0092] According to a preferred embodiment of the present invention, the temperature for aeration flotation is 10–40°C, preferably 10–25°C. The amine and carboxyl groups in the chemical structure of the flotation collector of the present invention increase the polarity of the collector, improve its water solubility and dispersibility at low temperatures, and broaden the temperature range for flotation of the pulp. However, the temperature cannot be too low, as this will affect the solubility and collecting ability of the amino acid-based collector. Excessive flotation temperature requires heating the pulp, increasing energy consumption. When the ADA collector concentration is 80 mg / L and the pulp pH is 11.5, at 10°C, the ADA collection recovery rate of quartz in quartz ore can reach over 90%.

[0093] Furthermore, in order to improve the harvesting efficiency, step (2) also includes adding an activator (Ca) to the slurry. 2 + Mg 2+ Ba 2+ wait).

[0094] Specifically, the activator activates the minerals, creating activation sites on the mineral surface. The dicarboxyl groups in the collector molecules of this invention are nucleophilic and can form stable complexes with metal ions. During flotation, this chelation effect increases the adsorption between the mineral surface and the flotation reagent, not only improving the flotation performance of the minerals but also enabling selective adsorption of minerals with metal ion active sites on their surfaces.

[0095] Furthermore, to improve the flotation recovery rate of minerals, the concentration of the activator in the pulp of the present invention is 0-60 mg / L. If the activator concentration is too low, it may not be able to effectively activate the minerals, resulting in a decrease in recovery rate; if the activator concentration is too high, it may consume too much collector or form precipitates on the mineral surface that are unfavorable to flotation.

[0096] To reduce the flotation of certain minerals in the slurry and achieve selective flotation, step (2) further includes adding inhibitors to the slurry. For example, when collecting and flotating quartz in a mineral sample, to prevent iron-bearing minerals from being unfloatable, starch inhibitors can be added to the sample to increase the hydrophilicity of the iron-bearing mineral surface, thereby inhibiting the collection of iron-bearing minerals. When inhibiting the flotation of other oxide minerals, corresponding inhibitors can be sought.

[0097] It should be noted that, by adjusting the specific flotation condition parameters, the amino acid collector of the present invention can not only achieve the flotation of quartz, but also be applied to the selective collection and flotation of oxide minerals such as calcite, apatite, fluorite, and scheelite.

[0098] Preparation Example 1

[0099] The preparation method of 2-[(5-amino-5-carboxymethyl)amino]lauric acid includes:

[0100] (1) Weigh 0.5 mol of dodecyl acid and add it to a 250 mL three-necked flask equipped with a stirrer, thermometer and spherical reflux condenser. Place it in a 75 °C constant temperature water bath to heat and melt it. Continue to raise the temperature to 85 °C, turn on the stirrer, add the catalyst phosphorus trichloride (PCl3), and stir at a constant temperature for 1 h.

[0101] (2) Raise the temperature of the reaction system in step (1) to 95°C, add 0.525 mol of liquid bromine to the system, slowly add it to the reaction system using a constant pressure separatory funnel, stir rapidly, control the adding time to 6 h, continue stirring the reaction for 5 h to allow the liquid bromine to react fully;

[0102] After the reaction is complete, the remaining liquid bromine in the three-necked flask is removed by vacuum pump. When the reactant turns pale yellow, the vacuum pump is stopped. A certain amount of sodium sulfite solution is added to neutralize the unreacted liquid bromine. Pure water is added to the reaction solution. The reaction solution is transferred to a separatory funnel to separate the lower water layer and the upper organic liquid layer, which is a pale yellow or milky white liquid, namely 2-bromododecanoic acid.

[0103] (3) Add 2-bromododecanoic acid and lysine in a ratio of 1:1.15 to a 250mL three-necked flask equipped with a stirrer, thermometer and spherical reflux condenser, add an appropriate amount of deionized water, heat to 95℃ in a water bath and react at a constant temperature for 5h.

[0104] After the reaction was completed, the reaction product was transferred to a 250 ml separatory funnel, and water was added for extraction three times to obtain a pale yellow product. Excess water was removed by distillation at 70 °C under normal pressure for 10 h to obtain the final product 1.

[0105] The infrared spectrum of product 1 is shown below. Figure 1 As shown, the spectrum contains vibrational absorption peaks related to secondary amine and carboxyl groups at 3430 cm⁻¹. -1 1625cm -1 This indicates that the bromination and substitution reactions in the preparation method were successfully completed. A primary amine vibrational absorption peak at 1563 cm⁻¹ is present in the spectrum. -1 This indicates that only one of the two amino groups in lysine reacted with the α-halofatty acid. The amino group at the end of the lysine side chain is highly reactive and can react with carboxylic acids to form an amide bond. Therefore, the α-halofatty acid reacted with the amino group on the lysine side chain.

[0106] Figure 2 Mass spectrometry results using ESI as the ionization source (methanol as solvent; mode: positive ion) are shown. The results show addition ion peaks of [M+H]-, [M+Na]-, and [M+K]-, indicating that 2-[(5-amino-5-carboxymethyl)amino]lauric acid was successfully synthesized.

[0107] The yield of product 1 was calculated to be 62% based on the amount of substance before and after the reaction.

[0108] Preparation Example 2

[0109] The same preparation method as in Preparation Example 1 was used, except that the amount of phosphorus trichloride catalyst added in step (1) was 3g, and the final product 2 was obtained.

[0110] Infrared spectroscopy and mass spectrometry using ESI as the ionization source were performed on product 2. The test results showed that 2-[(5-amino-5-carboxymethyl)amino]lauric acid was successfully synthesized in preparation example 2.

[0111] The yield of product 2 was calculated to be 52% based on the amount of substance before and after the reaction.

[0112] Preparation Example 3

[0113] The same preparation method as in Preparation Example 1 was used, except that in step (2), the temperature of the reaction system was raised to 105°C to obtain the final product 3.

[0114] Infrared spectroscopy and mass spectrometry using ESI as the ionization source were performed on product 3. The test results showed that 2-[(5-amino-5-carboxymethyl)amino]lauric acid was successfully synthesized in preparation example 3.

[0115] Based on the amount of substance before and after the reaction, the yield of product 3 was found to be 48%.

[0116] Preparation Example 4

[0117] The same preparation method as in Preparation Example 1 was used, except that the amount of liquid bromine added in step (2) was 0.55 mol, and the final product 4 was obtained.

[0118] Infrared spectroscopy and mass spectrometry using ESI as the ionization source were performed on product 4. The test results showed that 2-[(5-amino-5-carboxymethyl)amino]lauric acid was successfully synthesized in preparation example 4.

[0119] Based on the amount of substance before and after the reaction, the yield of product 4 was found to be 50%.

[0120] Preparation Example 5

[0121] The same preparation method as in Preparation Example 1 was used, except that the molar ratio of 2-bromododecanoic acid: lysine: sodium hydroxide in step (3) was 1:1.15:0.69, and the final product 5 was obtained.

[0122] Infrared spectroscopy and mass spectrometry using ESI as the ionization source were performed on product 5. The test results showed that 2-[(5-amino-5-carboxymethyl)amino]lauric acid was successfully synthesized in preparation example 5.

[0123] Based on the amount of substance before and after the reaction, the yield of product 5 was 45%.

[0124] Preparation Example 6

[0125] The same preparation method as in Preparation Example 1 was used, except that in step (3), the temperature of the water bath was raised to 110°C to obtain the final product 6.

[0126] Infrared spectroscopy and mass spectrometry using ESI as the ionization source were performed on product 6. The test results showed that 2-[(5-amino-5-carboxymethyl)amino]lauric acid was successfully synthesized in preparation example 6.

[0127] Based on the amount of substance before and after the reaction, the yield of product 6 was found to be 55%.

[0128] Preparation Example 7

[0129] The same preparation method as in Preparation Example 1 was used, except that the dodecyl acid in Preparation Example 1 was replaced with tetradecyl acid to obtain the final product 7.

[0130] Infrared spectroscopy and mass spectrometry using ESI as the ionization source were performed on product 7. The test results showed that 2-[(5-amino-5-carboxymethyl)amino]tetradecanoic acid was successfully synthesized in preparation example 7.

[0131] Based on the amount of substance before and after the reaction, the yield of product 7 was 60%.

[0132] Preparation Example 8

[0133] The same preparation method as in Preparation Example 1 was used, except that the dodecyl acid in Preparation Example 1 was replaced with n-decanoic acid to obtain the final product 8.

[0134] Infrared spectroscopy and mass spectrometry using ESI as the ionization source were performed on product 8. The test results showed that 2-[(5-amino-5-carboxymethyl)amino]decanoic acid was successfully synthesized in preparation example 8.

[0135] Based on the amount of substance before and after the reaction, the yield of product 8 was found to be 58%.

[0136] In Examples 1-5 below, 2-[(5-amino-5-carboxymethyl)amino]dodecanoic acid prepared in Preparation Example 1 was used for the flotation of quartz ore.

[0137] The quartz ore was obtained from Anshan, Liaoning Province, China. The purity of the ore sample was above 96%, and the particle size of the flotation sample was 37-74 μm. Sodium oleate, a traditional fatty acid collector, was used as a reference reagent to conduct single-mineral flotation experiments on quartz. The specific steps included:

[0138] (1) Add 2g of the mineral sample to be processed into a 40mL flotation cell, add 38mL of ultrapure water, and adjust the slurry for 2min;

[0139] (2) Add pH adjuster to the slurry and adjust to the predetermined pH;

[0140] (3) Add calcium chloride, an activator, to the slurry obtained in step (2), stir for 2 minutes, and then add sodium oleate, a collector, to obtain slurry 1.

[0141] Add the collector 2-[(5-amino-5-carboxymethyl)amino]lauric acid (ADA) directly to the slurry obtained in step (2) to obtain slurry 2;

[0142] (4) Stir slurry 1 and slurry 2 for 2 minutes respectively, and then perform aeration flotation for 2 minutes.

[0143] (5) After flotation, the froth product, i.e. the concentrate and the product in the tank, are filtered, dried, weighed, and the flotation recovery rate is calculated.

[0144] Example 1

[0145] Single-mineral flotation experiments were conducted on quartz at a temperature of 25℃. In step (2), the pH of the pulp was adjusted to 3, 5, 7, 10, 11.5, 12, and 13, respectively. In step (3), the concentration of sodium oleate was 60 mg / L, and the concentration of ADA was 80 mg / L. The flotation recovery data obtained are as follows: Figure 1 As shown.

[0146] Figure 1 The results show the variation of quartz flotation recovery with pH at 25°C for collectors 2-[(5-amino-5-carboxymethyl)amino]lauric acid (ADA) and sodium oleate (NaOL). Figure 1 It can be seen that the collecting effects of ADA and sodium oleate are not significant in the acidic to neutral range; as the pH value increases, the collecting abilities of ADA and sodium oleate gradually increase; when the pH value exceeds 11.5, the collecting effect of ADA begins to weaken. This indicates that an alkaline environment is favorable for the collection of both collectors, and under alkaline conditions, the collecting effect of ADA is more significant than that of sodium oleate; there is an optimal pH range, approximately 11-13, outside of which the collecting efficiency drops below 80%.

[0147] Example 2

[0148] Single-mineral flotation experiments were conducted on quartz at a temperature of 25℃ and a pH of 11.5. In step (3), the concentrations of sodium oleate were 15 mg / L, 30 mg / L, 40 mg / L, 60 mg / L, 70 mg / L, and 80 mg / L, and the concentrations of ADA were 20 mg / L, 30 mg / L, 40 mg / L, 60 mg / L, 80 mg / L, and 90 mg / L. The flotation recovery data obtained are as follows: Figure 2 As shown.

[0149] Figure 2 The graph shows the change in quartz flotation recovery with the amount of collector added, under the conditions of temperature 25℃ and pH 11.5, when the collectors are 2-[(5-amino-5-carboxymethyl)amino]lauric acid (ADA) and sodium oleate (NaOL). Figure 2It can be seen that for sodium oleate, the relationship between its dosage and recovery rate shows a trend of first increasing and then decreasing. The flotation effect reaches its optimal state when the dosage of sodium oleate reaches 60 mg / L. For ADA, the relationship also shows a trend of first increasing and then decreasing. However, unlike sodium oleate, when the dosage of ADA is 60 mg / L, under the same temperature and pH conditions, the recovery rate of ADA for quartz is much higher than that of sodium oleate for silica. Only when the dosage of ADA reaches 80 mg / L does the recovery rate show a slight decrease. Therefore, considering both flotation efficiency and cost-effectiveness, the optimal collector dosage of ADA at 25℃ is 80 mg / L.

[0150] Example 3

[0151] Single-mineral flotation experiments were conducted on quartz under the conditions of pH = 11.5, ADA dosage of 80 mg / L, and oleic acid dosage of 60 mg / L. In step (1), the pulp temperatures were 10℃, 15℃, 20℃, 25℃, 30℃, 35℃, and 40℃, respectively. The flotation recovery data obtained are as follows: Figure 3 As shown.

[0152] Figure 3 The graph shows the change in quartz flotation recovery with temperature when the pulp pH is 11.5 and the collectors are 2-[(5-amino-5-carboxymethyl)amino]lauric acid (ADA) and sodium oleate (NaOL). Figure 3 It can be seen that temperature has a significantly different effect on the flotation recovery rate of the two collectors. Sodium oleate is very sensitive to temperature changes, especially at low temperatures, where its flotation performance drops sharply. When the ambient temperature drops to 10℃, sodium oleate can hardly achieve effective flotation. This indicates that the flotation process of sodium oleate is strongly dependent on suitable temperature conditions and lacks low-temperature adaptability. In contrast, ADA's flotation performance is more adaptable to temperature changes; even at a lower temperature of 10℃, ADA can still maintain a flotation efficiency of nearly 90%. This shows that the flotation process of ADA is relatively unaffected by low temperatures and can maintain stable flotation capability over a wider temperature range. Therefore, ADA exhibits superior low-temperature flotation adaptability and stability compared to sodium oleate in low-temperature environments.

[0153] Example 4

[0154] Single-mineral flotation experiments were conducted on quartz at a temperature of 10℃. In step (2), the pH of the pulp was adjusted to 3, 5, 7, 10, 11.5, 12, and 13, respectively; in step (3), the concentration of sodium oleate was 70 mg / L, and the concentration of ADA was 80 mg / L. The obtained flotation recovery data are as follows: Figure 4 As shown.

[0155] Figure 4 The graph shows the change in quartz flotation recovery with pH at 10℃ when the collectors are 2-[(5-amino-5-carboxymethyl)amino]lauric acid (ADA) and sodium oleate (NaOL). Figure 4 It can be seen that the flotation process of sodium oleate and ADA is significantly affected by pH at 10℃. In acidic or neutral environments, the recovery rates of both are unsatisfactory, and the flotation effect is poor. However, when the pH of the solution increases to the alkaline range, the flotation recovery rate increases accordingly, showing better flotation performance. Especially at pH values ​​of 11-13, the flotation effect reaches its optimal state. In this strongly alkaline environment, ADA exhibits a stronger collecting ability than sodium oleate. Experimental data show that when the pH value is 12, the recovery rate of ADA exceeds 90%, while the recovery rate of sodium oleate is less than 50%. Therefore, under the specific conditions of low temperature (10℃) and alkaline solution, ADA, as a collector, demonstrates a superior flotation effect compared to sodium oleate. This means that in situations requiring efficient recovery of specific substances, especially in low-temperature alkaline environments, using ADA as a collector may be more effective.

[0156] Example 5

[0157] Single-mineral flotation experiments were conducted on quartz at a temperature of 10℃ and pH = 11.5. In step (3), the concentrations of sodium oleate were 15 mg / L, 40 mg / L, 60 mg / L, 70 mg / L, and 80 mg / L, and the concentrations of ADA were 20 mg / L, 40 mg / L, 60 mg / L, 70 mg / L, 80 mg / L, and 90 mg / L. The flotation recovery data obtained are as follows: Figure 5 As shown.

[0158] Figure 5 The graph shows the change in quartz flotation recovery with the amount of collector added at 10℃ and pH=11.5, with the collectors being 2-[(5-amino-5-carboxymethyl)amino]lauric acid (ADA) and sodium oleate (NaOL). Figure 5 It can be seen that, when the temperature is maintained at 10℃ and the solution pH is 11.5, regardless of the type of collector used, the collection efficiency increases and then decreases with increasing dosage; and Figure 4 A comparison of collector dosages at 25℃ showed that when the pulp temperature dropped to 10℃, the optimal collector dosage for ADA remained at 80 mg / L, while the optimal dosage for sodium oleate increased to 70 mg / L. Within the dosage range of 15-90 mg / L, ADA significantly outperformed sodium oleate in collecting activity. This further demonstrates ADA's superior temperature adaptability and confirms its high efficiency and practicality in mineral flotation processes.

[0159] Furthermore, from the flotation process and flotation results of the above application examples ( Figure 1-5 As can be seen, before using sodium oleate collector for flotation of ore pulp, it is necessary not only to adjust the pH of the ore pulp but also to add calcium chloride activator to activate the mineral surface, providing active sites for the adsorption of sodium oleate collector, thereby achieving flotation. In contrast, before using the collector of this invention for flotation of ore pulp, only the pH of the ore pulp needs to be adjusted; no activator is needed to activate the mineral surface, and a better flotation recovery rate can be obtained. Therefore, using the collector of this invention can simplify the ore pulp flotation process, reduce reagent usage, and lower costs. In addition, compared with sodium oleate, amino acid collectors have low toxicity, low volatility, and biodegradability, making them environmentally friendly.

[0160] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A process for the preparation of a flotation collector, characterized by, The preparation method includes: (1) Fatty acids are reacted with halogenating reagents to prepare α-halogenated fatty acids; (2) Dissolve lysine in an alkaline solution, then add the α-halo fatty acid, and react the α-halo fatty acid with lysine; The fatty acid is one or more of decanoic acid, dodecyl acid, and tetradecyl acid; The flotation collector is a compound represented by formula (1): Formula (1), n = 7, 9 or 11.

2. The production method according to claim 1, characterized by, In step (2), the molar ratio of lysine to the solute in the alkaline solution is 1:0.4-0.

6.

3. The preparation method according to claim 1, characterized in that, In step (2), the molar ratio of the α-halo fatty acid to the lysine is 1:1.1-1.

2.

4. The method of claim 1, wherein, In step (2), the reaction temperature is 95-110℃ and the time is 4-6h.

5. An oxidic mineral flotation process, characterized by, The flotation method includes: (1) The ore sample to be processed is slurry prepared to obtain ore slurry; (2) Adjust the pH of the slurry and add the collector prepared according to the preparation method described in claim 1; (3) Aeration flotation.

6. The flotation method according to claim 5, characterized in that, In step (2), the pH of the slurry is 7-14, and the concentration of the collector is 40-100 mg / L.

7. The flotation method according to claim 5, characterized in that, In step (3), the temperature of the aeration flotation is 10-40℃ and the time is 2-3 min.

8. The flotation method according to claim 5, characterized in that, Step (2) also includes adding an activator to the slurry.

9. The flotation method according to claim 5, characterized in that, The oxidized minerals are selected from one or more of the following: quartz, iron ore, calcite, apatite, fluorite, and scheelite.

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