Synthesis method and application of carboxymethyl-phosphorylated bifunctional chitosan inhibitor

Abstract

The invention belongs to the technical field of mineral processing, and particularly relates to a synthetic method and application of a carboxymethyl-phosphorylated bifunctional chitosan inhibitor. The synthetic method of the carboxymethyl-phosphorylated bifunctional chitosan inhibitor comprises the following steps: (1) carrying out acid activation pretreatment; (2) phosphorylation reaction; (3) carboxymethylation modification; and (4) carrying out solid-liquid separation and drying. The invention also provides an application of the carboxymethyl-phosphorylated bifunctional chitosan inhibitor. According to the synthetic method of the carboxymethyl-phosphorylated bifunctional chitosan inhibitor disclosed by the invention, the synthesized carboxymethyl-phosphorylated chitosan inhibitor realizes the function switching of'two states in one dose ', the tedious operation of frequently replacing medicaments in the traditional process is avoided, and meanwhile, the medicament residue interference is eliminated.

Description

Technical Field

[0001] The invention belongs to the technical field of mineral processing, and specifically relates to a synthesis method and application of a carboxymethyl-phosphorylated bifunctional chitosan inhibitor. Background Art

[0002] The difficulty in flotation separation of scheelite, fluorite and calcite stems from the similarity of their surface chemical properties. All three use calcium ions as the main surface active sites, and the charge distribution and coordination ability of the anionic groups are similar. In conventional flotation systems, anionic collectors bind to Ca2+ via carboxyl groups. 2+ The non-specific chelation of the three minerals caused them to be adsorbed on the surfaces of the three minerals simultaneously, resulting in minimal differences in their floatability. In addition, the simultaneous influence of the pH control of the slurry on the surface potential of the three minerals further weakened the potential for selective separation based on electrostatic repulsion.

[0003] Although traditional inhibitors can inhibit non-target minerals through physical covering or weak chemical adsorption, they have significant defects: inhibitors represented by water glass cover the mineral surface by generating silica colloids, but have poor selectivity. While inhibiting calcite and fluorite, they also affect the floatability of scheelite. Although starch inhibitors are environmentally friendly, they rely on hydrogen bond adsorption and lack differentiation in affinity for calcium-containing minerals. Lead salts are often required to activate scheelite, which brings the risk of heavy metal pollution.

[0004] In addition, the existing process adopts a multi-stage "inhibition-activation" process (such as first inhibiting fluorite / calcite to float scheelite, then activating fluorite and inhibiting calcite), but it faces a double contradiction: the inhibitor residue hinders the selective activation of fluorite by the subsequent activator; the reactivation of fluorite after inhibition requires a high dose of activator, and calcite is easily co-activated, resulting in serious inter-containment of concentrates. However, this "strong pressure and strong pull" flotation not only has many types of reagents and large dosages, but also has extremely low reactivation efficiency after fluorite inhibition. When the dosage of activator is large, calcite is also easily activated, resulting in poor separation efficiency of the three. Therefore, developing new and efficient inhibitors, reducing the types of reagents, and improving the targeted inhibition of reagents are important directions of current research.

[0005] Chitosan is a natural polysaccharide with amino groups (-NH 2 ) and hydroxyl (-OH) groups have potential selective adsorption capacity, but unmodified chitosan has inherent defects: (1) poor solubility, especially in alkaline slurries, it is easy to flocculate and precipitate, resulting in inhibition failure; (2) adsorption depends on weak hydrogen bonds / electrostatic effects, has low binding force, and is easy to desorb in high shear slurries; (3) the pH response range is narrow, and the inhibition ability decreases sharply after deprotonation of the amino group; (4) although modified chitosan can introduce functional groups (such as phosphate groups), the problem of "simultaneous inhibition of dual minerals" still exists, resulting in the loss of high-value fluorite.

[0006] Therefore, it is necessary to explore a new type of chitosan inhibitor for the selective separation of scheelite, fluorite and calcite. Summary of the invention

[0007] The purpose of the present invention is to provide a method for synthesizing a carboxymethyl-phosphorylated bifunctional chitosan inhibitor, which solves a series of problems such as poor selectivity of traditional inhibitors, poor solubility and dispersibility of single chitosan, unstable adsorption, limited pH adaptability, susceptibility to the influence of the ore pulp environment, and a large number of "strong pressure and strong pull" flotation reagents and a large amount of use; the present invention also provides its application.

[0008] The method for synthesizing the carboxymethyl-phosphorylated bifunctional chitosan inhibitor of the present invention comprises the following steps: (1) Acid activation pretreatment The chitosan powder and the citric acid aqueous solution are uniformly mixed and stirred to react to prepare an activated chitosan dispersion; (2) Phosphorylation reaction Add phosphate and magnesium sulfate to the activated chitosan dispersion prepared in step (1), and react at 80-90° C. for 2-4 hours to prepare phosphorylated chitosan; (3) Carboxymethylation Adding sodium chloroacetate to the phosphorylated chitosan prepared in step (2), then adding sodium hydroxide to adjust the pH value of the reaction system to 7-8, and stirring the reaction to generate carboxymethyl-phosphorylated bifunctional chitosan; (4) Solid-liquid separation and drying The carboxymethyl-phosphorylated bifunctional chitosan prepared in step (3) is precipitated with ethanol, then washed with an ethanol-water mixture and a NaOH solution in sequence, and dried to obtain a carboxymethyl-phosphorylated bifunctional chitosan inhibitor.

[0009] in: The chitosan powder in step (1) has a deacetylation degree of 85%-95% and a molecular weight of 50-200 kDa.

[0010] In step (1), the mass concentration of the citric acid aqueous solution is 1-3wt%, and the mass ratio of the chitosan powder to the citric acid aqueous solution is 1:10-1:15.

[0011] In step (1), the stirring and mixing temperature is 40-60° C., and the stirring and mixing time is 30-60 min.

[0012] The phosphate in step (2) is one of disodium hydrogen phosphate, sodium dihydrogen phosphate or trisodium phosphate.

[0013] In step (2), the mass ratio of phosphate to activated chitosan dispersion is 0.5:1-3:1, the mass of magnesium sulfate accounts for 0.5-2wt% of the mass of phosphate, and magnesium sulfate serves as a catalyst for the phosphorylation reaction.

[0014] In step (3), the mass ratio of phosphorylated chitosan, sodium chloroacetate and sodium hydroxide is 1:0.5-3:0.3-1.5.

[0015] The stirring reaction temperature in step (3) is 50-80° C., and the stirring reaction time is 2-6 h.

[0016] In step (4), the mass ratio of ethanol to carboxymethyl-phosphorylated bifunctional chitosan is 4:1.

[0017] The volume ratio of ethanol to water in the ethanol-water mixture in step (4) is 4:1-2:1, and the washing time is 5-20 minutes.

[0018] The concentration of the NaOH solution in step (4) is 0.2-0.4 mol / L, and the washing time is 10-30 min.

[0019] In step (4), vacuum drying is used for drying, the drying temperature is 40-60°C, and the drying time is 12-24h.

[0020] The application of the carboxymethyl-phosphorylated bifunctional chitosan inhibitor of the present invention is used for the flotation separation of scheelite, fluorite and calcite, and comprises the following steps: ① Grind the ore containing scheelite, fluorite and calcite to -0.074 mm, accounting for 50%-95%, then adjust the pH value of the slurry to 8-10, add carboxymethyl-phosphorylated bifunctional chitosan inhibitor and anion collector successively, and obtain scheelite rough concentrate and mixed tailings containing fluorite and calcite through one roughing, multiple cleaning and multiple sweeping; ② adjusting the pH value of the scheelite rough concentrate slurry prepared in step ① to 8-10, adding a carboxymethyl-phosphorylated bifunctional chitosan inhibitor and an anion collector, and subjecting the scheelite concentrate and the concentrated tailings to one roughing, multiple concentrating and multiple scavenging at room temperature; ③ The pH value of the mixed tailings slurry containing fluorite and calcite prepared in step ① is adjusted to 4-6, a carboxymethyl-phosphorylated bifunctional chitosan inhibitor and a cationic collector are added, and fluorite concentrate and calcite-containing tailings are obtained through one roughing, multiple cleaning and multiple scavenging.

[0021] in: The mass concentration of the flotation pulp in step ① is 25%-45%.

[0022] In step ①, sodium hydroxide or sodium carbonate is added to adjust the pH value of the slurry to 8-10.

[0023] In step ①, the dosage of the carboxymethyl-phosphorylated bifunctional chitosan inhibitor is 100-500 g / t, and the anion collector is at least one of sodium oleate, oleic acid, sodium dodecyl sulfate or sodium dodecyl sulfonate, and the dosage is 300-1000 g / t.

[0024] The number of times of concentration in step ① is 2-3 times, and the carboxymethyl-phosphorylated bifunctional chitosan inhibitor is added to the scheelite flotation concentration operation, and the amount used is 1 / 4-1 / 2 of the previous operation.

[0025] The number of scavenging in step ① is 3 times, and anion collector is added in the flotation scavenging operation of scheelite, and the amount used is 1 / 4-1 / 2 of the previous operation.

[0026] In step ②, the mass concentration of the scheelite coarse concentrate slurry is 10%-20%.

[0027] In step ②, the amount of carboxymethyl-phosphorylated bifunctional chitosan inhibitor is 100 g / t-500 g / t, and the anion collector is at least one of sodium oleate, oleic acid, sodium dodecyl sulfate or sodium dodecyl sulfonate, and the amount is 100 g / t-200 g / t.

[0028] In step ②, the number of selections is 3-4 times, and the number of scans is 2-3 times.

[0029] The mass concentration of the flotation pulp in step ③ is 20%-40%.

[0030] In step ③, one of sulfuric acid, hydrochloric acid or oxalic acid is added to adjust the pH value of the slurry to 4-6.

[0031] In step ③, the dosage of the carboxymethyl-phosphorylated bifunctional chitosan inhibitor is 200-500 g / t, and the cationic collector is at least one of dodecylamine, octadecylamine or etheramine collectors, and the dosage is 100-500 g / t.

[0032] In step ③, the number of selections is 6-7 times, and the number of scans is 2 times.

[0033] Compared with the prior art, the present invention has the following beneficial effects: (1) The method for synthesizing the carboxymethyl-phosphorylated bifunctional chitosan inhibitor of the present invention realizes the "one dose, two states" functional switching, avoids the tedious operation of frequently changing reagents in the traditional process, and eliminates the interference of residual reagents; the introduction of carboxymethyl is conducive to improving the inhibitor to maintain high stability and selectivity in the pH range of 4-10: the buffering capacity of carboxymethyl (pKa≈4.3) can neutralize the local pH fluctuation of the slurry, ensuring the stability of the inhibitory effect; in addition, the carboxymethyl chelates Ca in the slurry 2+ / Mg 2+ , reducing the competitive consumption of hardness ions on phosphate groups.

[0034] (2) The method for synthesizing the carboxymethyl-phosphorylated bifunctional chitosan inhibitor of the present invention uses citric acid instead of traditional concentrated hydrochloric acid or sulfuric acid to pretreat chitosan. Citric acid mildly hydrolyzes the β-1,4 glycosidic bonds of chitosan through its carboxylic acid group (-COOH), partially opening the crystalline region and exposing more hydroxyl (-OH) and amino (-NH 2 ) active sites, while avoiding excessive degradation of the molecular chain caused by strong acid. At the same time, citric acid molecules can bind to chitosan through hydrogen bonds, and some carboxylic acid groups remain on the surface of chitosan, providing pre-activated sites for subsequent phosphorylation reactions and enhancing the uniformity of phosphate substitution. The introduction of carboxylic acid groups on the surface of chitosan after pretreatment gives it initial pH sensitivity (carboxylic acid group pKa≈3.1), laying the foundation for subsequent dual functionalization.

[0035] (3) The method for synthesizing the carboxymethyl-phosphorylated bifunctional chitosan inhibitor of the present invention comprises adding magnesium sulfate as a catalyst in the phosphorylation reaction. 2+ It forms a soluble complex with phosphate, promotes the directional attack of phosphate ions on chitosan hydroxyl groups, and avoids the production of by-products by traditional urea catalysis. At the same time, constant temperature control is adopted to react in a water bath at 80-90℃ to ensure that the phosphate group (-PO 3 H 2 ) Preferentially replace C 6 Hydroxyl, avoid C 3 Random modification of hydroxyl groups improves the controllability of molecular structure. Stepwise ionization of phosphate groups (pK a1 ≈2.1, pK a2 ≈7.2, pK a3 ≈12.3) endows the agent with a wide range of pH response capabilities, especially under alkaline conditions with -PO 3 2- The form preferentially chelates calcium-containing minerals.

[0036] (4) The method for synthesizing the carboxymethyl-phosphorylated bifunctional chitosan inhibitor of the present invention is to first phosphorylate and then carboxymethylate during the synthesis process, thereby avoiding the competitive reaction between sodium chloroacetate (a strong nucleophilic reagent) and the phosphate group and ensuring that the carboxymethyl group is accurately introduced into the C 6 The remaining hydroxyl groups can realize the bifunctional groups (-PO 3 H 2 With -CH 2 COO - ) spatial separation, reducing steric hindrance effects. In addition, sodium hydroxide was used to adjust the reaction system to a weak alkalinity, which prompted sodium chloroacetate to preferentially react with chitosan hydroxyl groups to undergo Williamson etherification rather than N-carboxymethylation of amino groups, thereby retaining the pH response activity of amino groups. The introduction of carboxyl groups expanded the pH response range of the agent, and under acidic conditions, the -CH 2 The COOH form reduces the electrostatic repulsion with scheelite and cooperates with the -PO 3 H - Achieve calcite targeted inhibition.

[0037] (5) The method for synthesizing the carboxymethyl-phosphorylated bifunctional chitosan inhibitor of the present invention introduces carboxymethyl and phosphate groups into chitosan, wherein the carboxymethyl group imparts strong hydrophilicity to the agent, allowing it to dissolve rapidly and disperse evenly in the slurry at room temperature, thus avoiding the drawback of traditional inhibitors (such as starch and water glass) that require heating due to insufficient solubility at low temperatures; and the phosphate group directly anchors the Ca2+ of fluorite and calcite through chemical chelation. 2+ Active sites can form stable five-membered ring chelates at room temperature without relying on thermal energy to enhance adsorption kinetics. At the same time, its pH responsiveness dynamically regulates the inhibition behavior, rejecting scheelite under alkaline conditions and inhibiting calcite under acidic conditions. Compared with the traditional scheelite selection process, which needs to be heated to above 70°C to activate the agent or destroy the hydration layer on the surface of the mineral, this inhibitor has high solubility, strong adsorption efficiency and precise selectivity at room temperature.

[0038] (6) The carboxymethyl-phosphorylated bifunctional chitosan inhibitor of the present invention is used to insert a phosphate group and a carboxymethyl group into chitosan through phosphorylation reaction and carboxymethylation modification to form a carboxymethyl-phosphorylated bifunctional chitosan, wherein the carboxymethyl group is converted into -CH 2 COO - In the form of scheelite, it will repel scheelite, and the phosphate group will ionize to -PO 3 2- , with Ca in fluorite and calcite 2+ It forms a five-membered ring chelate, which can then target and inhibit fluorite and calcite; under acidic conditions (pH 4-6), the carboxyl group is -CH 2 The presence of COOH will reduce the hydrogen bonding with fluorite, while the phosphate group exists in the form of -PO3 H - The inhibition of calcite is strengthened in the form of chitosan, thereby forming a bifunctional pH-responsive inhibitor based on chitosan. The effective separation of scheelite, fluorite and calcite can be achieved simply by adjusting the pH of the slurry.

[0039] (7) The application of the carboxymethyl-phosphorylated bifunctional chitosan inhibitor of the present invention utilizes the carboxymethyl (-CH 2 COOH) and phosphate (-PO 3 H 2 ) under different pH conditions. In an alkaline environment, the carboxyl group ionizes to -CH 2 COO-, and WO on the surface of scheelite 4 2- Produce electrostatic repulsion, reduce its adsorption, and at the same time the phosphate group with -PO 3 2- Form-selective chelation of Ca from fluorite and calcite 2+ , inhibiting its flotation; under acidic conditions, the phosphate group is partially protonated to -PO 3 H - , preferentially with the active Ca 2+ Combined with amino groups (-NH 2 ) is protonated to -NH 3 + , the adsorption of calcite is enhanced by electrostatic action, and the carboxyl group is restored to neutrality (-CH 2 COOH), weakening the inhibition of fluorite, thus achieving step-by-step selective inhibition. This multi-functional group-coordinated pH response mechanism enables a single reagent to dynamically adapt to the needs of different flotation stages and achieve precise separation of calcium-containing minerals with similar surface properties.

[0040] (8) The application of the carboxymethyl-phosphorylated bifunctional chitosan inhibitor of the present invention utilizes Ca2+ on the surface of scheelite, fluorite and calcite to 2+ Activity difference, through pH regulation to accurately match the inhibitor action mode, first under alkaline conditions, CO on the calcite surface 3 2- Ionization enhancement, Ca 2+ High dissolution volume, preferentially absorbed by -PO 3 2- Chelated, fluorite surface F - Ionization limited, Ca 2+ Scheelite WO is second in activity. 4 2- Strong negative charge, electrostatic repulsion - CH 2 COO - , ensuring its floatability; while in acidic conditions: CO3 2- Converted to HCO 3 - / CO 2 , Ca 2+ The dissolution amount further increased with -PO 3 H - The binding capacity is enhanced, and at the same time, the F⁻ ionization of the fluorite surface increases, the surface negative charge increases, and the inhibition of adsorption is weakened. Through the synergy of pH and reagents to "amplify" the differences in mineral characteristics, the flotation separation of scheelite, fluorite and calcite with a single inhibitor is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a schematic diagram of the synthesis process of the carboxymethyl-phosphorylated bifunctional chitosan inhibitor of the present invention; Figure 2 It is a schematic diagram of the flotation application of the carboxymethyl-phosphorylated bifunctional chitosan inhibitor described in the present invention in separating scheelite, fluorite and calcite. DETAILED DESCRIPTION

[0042] The present invention is further described below with reference to the embodiments.

[0043] Example 1 The method for synthesizing the carboxymethyl-phosphorylated bifunctional chitosan inhibitor described in Example 1 comprises the following steps: (1) Acid activation pretreatment: chitosan powder (chitosan with a deacetylation degree of 92% and a molecular weight of 100 kDa) was mixed with a 2 wt % citric acid aqueous solution at a mass ratio of 1:13, and stirred at 50 °C for 40 minutes to obtain an activated chitosan dispersion; (2) Phosphorylation reaction: disodium hydrogen phosphate was added to the activated chitosan dispersion, the mass ratio of disodium hydrogen phosphate to chitosan dispersion was 1:1, and 1 wt% magnesium sulfate was added as a catalyst. The reaction was carried out in a water bath at 80°C for 4 hours to obtain phosphorylated chitosan. (3) Carboxymethylation modification: Sodium chloroacetate was added to the phosphorylated chitosan, and then sodium hydroxide was added to adjust the pH of the reaction system to 7. The mass ratio of phosphorylated chitosan, sodium chloroacetate and sodium hydroxide was 1:2:1. The reaction was stirred at 80 °C for 2 hours to generate carboxymethyl-phosphorylated bifunctional chitosan. (4) Solid-liquid separation and drying: The carboxymethyl-phosphorylated bifunctional chitosan obtained above was precipitated with ethanol at a mass ratio of ethanol to carboxymethyl-phosphorylated bifunctional chitosan of 4:1, and then washed with a mixed solution of ethanol and water at a volume ratio of 3:1 for 13 min and a 0.3 mol / L NaOH solution for 20 min, and dried (vacuum drying was used at a drying temperature of 50°C for a drying time of 18 h) to obtain the carboxymethyl-phosphorylated chitosan inhibitor.

[0044] The application of the carboxymethyl-phosphorylated bifunctional chitosan inhibitor described in Example 1 for flotation separation of scheelite, fluorite and calcite consists of the following steps: ①Using a tungsten mine in Hunan, the ore contains WO 3 The grade is 0.353%, CaF 2 The grade is 25.73%, CaCO 3 The grade is 25.17%. The ore is ground to -0.074 mm, accounting for 75%. Then, sodium hydroxide is added to adjust the pH of the slurry (the mass concentration of the flotation slurry is 35%) to 8. 500 g / t of the carboxymethyl-phosphorylated bifunctional chitosan inhibitor prepared in Example 1 and 1000 g / t of sodium oleate are added successively. Scheelite is recovered through one roughing, two fine cleanings and three scavengings, wherein 500 g / t, 250 g / t and 100 g / t of sodium oleate are added to scavenging I, scavenging II and scavenging III, respectively, and 200 g / t and 100 g / t of the carboxymethyl-phosphorylated bifunctional chitosan inhibitor prepared in Example 1 are added to fine cleaning I and fine cleaning II, respectively, to obtain a coarse scheelite concentrate and a mixed tailing containing fluorite and calcite. ② The pH of the scheelite rough concentrate slurry (the mass concentration of the scheelite rough concentrate slurry is 15%) is adjusted to 8 with sodium hydroxide, and 500 g / t of the carboxymethyl-phosphorylated bifunctional chitosan inhibitor prepared in Example 1 and 200 g / t of sodium oleate are successively added, and the scheelite is recovered by one roughing, four concentrating and three scavenging at room temperature, wherein 100 g / t, 50 g / t and 20 g / t of sodium oleate are added to scavenging I, scavenging II and scavenging III, respectively, 200 g / t and 100 g / t of the carboxymethyl-phosphorylated bifunctional chitosan inhibitor prepared in Example 1 are added to scavenging I and scavenging II, respectively, and no drug is added to scavenging III and scavenging IV, to obtain scheelite concentrate and concentrating tailings; ③ The pH of the mixed tailings slurry containing fluorite and calcite (the mass concentration of the flotation slurry is 30%) is adjusted to 4 with sulfuric acid, and 200 g / t of the carboxymethyl-phosphorylated bifunctional chitosan inhibitor prepared in Example 1 and 300 g / t of octadecylamine are added again. After one roughing, six concentrating and two scavenging, fluorite concentrate is obtained, wherein 100 g / t and 50 g / t of octadecylamine are added to scavenging I and scavenging II, respectively, 100 g / t and 50 g / t of the carboxymethyl-phosphorylated bifunctional chitosan inhibitor prepared in Example 1 are added to refined I and refined II, respectively, and refined III, refined IV, refined V and refined VI are not added with drugs to obtain fluorite concentrate and tailings containing calcite.

[0045] Comparative Example 1 The method for synthesizing the carboxymethyl-phosphorylated bifunctional chitosan inhibitor described in Comparative Example 1 comprises the following steps: (1) Dispersion: chitosan powder (chitosan with a deacetylation degree of 92% and a molecular weight of 100 kDa) was mixed with water at a mass ratio of 1:15, and stirred at 50°C for 40 minutes to obtain a chitosan dispersion; (2) Phosphorylation reaction: disodium hydrogen phosphate was added to the chitosan dispersion, the mass ratio of disodium hydrogen phosphate to chitosan dispersion was 1:1, and 1 wt% magnesium sulfate was added as a catalyst. The reaction was carried out in a water bath at 80°C for 4 hours to obtain phosphorylated chitosan. (3) Carboxymethylation modification: Sodium chloroacetate was added to the phosphorylated chitosan, and then sodium hydroxide was added to adjust the pH of the reaction system to 7. The mass ratio of phosphorylated chitosan, sodium chloroacetate and sodium hydroxide was 1:2:1. The reaction was stirred at 80°C for 2 hours to generate carboxymethyl-phosphorylated bifunctional chitosan. (4) Solid-liquid separation and drying: The carboxymethyl-phosphorylated bifunctional chitosan obtained above was precipitated with ethanol at a mass ratio of ethanol to carboxymethyl-phosphorylated bifunctional chitosan of 4:1, and then washed with a mixed solution of ethanol and water at a volume ratio of 3:1 for 13 min and a 0.3 mol / L NaOH solution for 20 min, and dried (vacuum drying was used at a drying temperature of 50°C for a drying time of 18 h) to obtain the carboxymethyl-phosphorylated chitosan inhibitor.

[0046] The application of the carboxymethyl-phosphorylated bifunctional chitosan inhibitor described in Comparative Example 1 is the same as that in Example 1, with the only difference being that the carboxymethyl-phosphorylated bifunctional chitosan inhibitor is prepared using Comparative Example 1.

[0047] Comparative Example 2 The synthesis method of the phosphorylated bifunctional chitosan inhibitor described in Comparative Example 2 consists of the following steps: (1) Acid activation pretreatment: chitosan powder (chitosan with a deacetylation degree of 92% and a molecular weight of 100 kDa) was mixed with a 2 wt % citric acid aqueous solution at a mass ratio of 1:13, and stirred at 50 °C for 40 minutes to obtain an activated chitosan dispersion; (2) Phosphorylation reaction: disodium hydrogen phosphate was added to the activated chitosan dispersion, the mass ratio of disodium hydrogen phosphate to chitosan dispersion was 1:1, and 1 wt% magnesium sulfate was added as a catalyst. The reaction was carried out in a water bath at 80°C for 4 hours to obtain phosphorylated chitosan. (3) Solid-liquid separation and drying: The phosphorylated chitosan obtained above was precipitated with ethanol at a mass ratio of 4:1 to phosphorylated chitosan. The mixture was washed with a 3:1 ethanol-water mixture for 13 min and a 0.3 mol / L NaOH solution for 20 min. The mixture was dried (vacuum drying at 50 °C for 18 h) to obtain a pH-responsive phosphorylated chitosan inhibitor.

[0048] The application of the phosphorylated chitosan inhibitor described in Comparative Example 2 is the same as that in Example 1, the only difference being that the phosphorylated chitosan inhibitor is prepared using Comparative Example 2.

[0049] Comparative Example 3 The synthesis method of the carboxymethyl chitosan inhibitor described in this comparative example 3 consists of the following steps: (1) Acid activation pretreatment: chitosan powder (chitosan with a deacetylation degree of 92% and a molecular weight of 100 kDa) was mixed with a 2 wt % citric acid aqueous solution at a mass ratio of 1:13, and stirred at 50 °C for 40 minutes to obtain an activated chitosan dispersion; (2) Carboxymethylation modification: Sodium chloroacetate was added to the activated chitosan dispersion, and then sodium hydroxide was added to adjust the pH of the reaction system to 7. The mass ratio of the activated chitosan dispersion, sodium chloroacetate and sodium hydroxide was 1:2:1. The mixture was stirred at 80°C for 2 hours to generate carboxymethyl chitosan. (3) Solid-liquid separation and drying: The carboxymethyl chitosan obtained above was precipitated with ethanol at a mass ratio of ethanol to carboxymethyl chitosan of 4:1, and then washed with a mixed solution of ethanol and water at a volume ratio of 3:1 for 13 min and a 0.3 mol / L NaOH solution for 20 min, and dried (vacuum drying was used at a drying temperature of 50°C for a drying time of 18 h) to obtain the carboxymethyl chitosan inhibitor.

[0050] The application of the carboxymethyl chitosan inhibitor described in Comparative Example 3 is the same as that in Example 1, the only difference being that the carboxymethyl chitosan inhibitor is prepared using Comparative Example 3.

[0051] Comparative Example 4 The method for synthesizing the carboxymethyl-phosphorylated bifunctional chitosan inhibitor described in this comparative example 4 comprises the following steps: (1) Acid activation pretreatment: chitosan powder (chitosan with a deacetylation degree of 92% and a molecular weight of 100 kDa) was mixed with a 2 wt % citric acid aqueous solution at a mass ratio of 1:13, and stirred at 50 °C for 40 minutes to obtain an activated chitosan dispersion; (2) Carboxymethylation modification: Sodium chloroacetate was added to the activated chitosan dispersion, and then sodium hydroxide was added to adjust the pH of the reaction system to 7. The mass ratio of the activated chitosan dispersion, sodium chloroacetate and sodium hydroxide was 1:2:1. The mixture was stirred at 80°C for 2 hours to generate carboxymethyl chitosan. (3) Phosphorylation reaction: disodium hydrogen phosphate was added to the carboxymethyl chitosan dispersion, the mass ratio of disodium hydrogen phosphate to carboxymethyl chitosan was 1:1, and 1 wt% magnesium sulfate was added as a catalyst. The reaction was carried out in a water bath at 80°C for 4 hours to obtain carboxymethyl-phosphorylated bifunctional chitosan. (4) Solid-liquid separation and drying: The carboxymethyl-phosphorylated bifunctional chitosan obtained above was precipitated with ethanol at a mass ratio of ethanol to carboxymethyl-phosphorylated bifunctional chitosan of 4:1, and then washed with a mixed solution of ethanol and water at a volume ratio of 3:1 for 13 min and a 0.3 mol / L NaOH solution for 20 min, and dried (vacuum drying was used at a drying temperature of 50°C for a drying time of 18 h) to obtain the carboxymethyl-phosphorylated chitosan inhibitor.

[0052] The application of the carboxymethyl-phosphorylated bifunctional chitosan inhibitor described in Comparative Example 4 is the same as that in Example 1, with the only difference being that the carboxymethyl-phosphorylated bifunctional chitosan inhibitor is prepared using Comparative Example 4.

[0053] Comparative Example 5 The flotation separation method of scheelite, fluorite and calcite described in this comparative example 5 consists of the following steps: ①Using a tungsten mine in Hunan, the ore contains WO 3 The grade is 0.353%, CaF 2 The grade is 25.73%, CaCO 3 The grade is 25.17%. The ore is ground to -0.074 mm, accounting for 75%. Then, sodium hydroxide is added to adjust the pH of the pulp (the mass concentration of the flotation pulp is 35%) to 8. 500g / t water glass and 1000g / t sodium oleate are added successively. Scheelite is recovered through one roughing, two fine cleaning and three scavenging. Among them, 500g / t, 250g / t and 100g / t of sodium oleate are added to scavenging I, scavenging II and scavenging III respectively, and 200g / t and 100g / t water glass are added to fine cleaning I and fine cleaning II respectively, to obtain a rough scheelite concentrate and a mixed tailing containing fluorite and calcite. ② Use sodium hydroxide to adjust the pH of the scheelite rough concentrate pulp (the mass concentration of the scheelite rough concentrate pulp is 15%) to 8, add 500g / t of water glass and 200g / t of sodium oleate successively, and recover the scheelite in the pulp at 90℃ through one roughing, four cleaning and three scavenging, wherein 100g / t, 50g / t and 20g / t of sodium oleate are added to scavenging I, scavenging II and scavenging III respectively, 200g / t and 100g / t of water glass are added to cleaning I and cleaning II respectively, and no reagent is added to cleaning III and cleaning IV, to obtain scheelite concentrate and cleaned tailings; ③ The pH value of the mixed tailings slurry containing fluorite and calcite (the mass concentration of the flotation slurry is 30%) is adjusted to 4 with sulfuric acid, and 200 g / t of acidified water glass and 300 g / t of octadecylamine are added again. After one roughing, six concentrating and two scavenging, fluorite concentrate is obtained, wherein 100 g / t and 50 g / t of octadecylamine are added to scavenging I and scavenging II respectively, 100 g / t and 50 g / t of acidified water glass are added to refining I and refining II respectively, and no drugs are added to refining III, refining IV, refining V and refining VI, to obtain fluorite concentrate and tailings containing calcite.

[0054] Comparative Example 6 The flotation separation method of scheelite, fluorite and calcite described in this comparative example 6 consists of the following steps: ①Using a tungsten mine in Hunan, the ore contains WO 3 The grade is 0.353%, CaF 2 The grade is 25.73%, CaCO 3 The grade is 25.17%. The ore is ground to -0.074 mm, accounting for 75%. Then, sodium hydroxide is added to adjust the pH of the pulp (the mass concentration of the flotation pulp is 35%) to 8. 500g / t water glass and 1000g / t sodium oleate are added successively. Scheelite is recovered through one roughing, two fine cleaning and three scavenging. Among them, 500g / t, 250g / t and 100g / t of sodium oleate are added to scavenging I, scavenging II and scavenging III respectively, and 200g / t and 100g / t water glass are added to fine cleaning I and fine cleaning II respectively, to obtain a rough scheelite concentrate and a mixed tailing containing fluorite and calcite. ② The pH value of the scheelite rough concentrate pulp (the mass concentration of the scheelite rough concentrate pulp is 15%) is adjusted to 8 with sodium hydroxide, and 500 g / t of water glass and 200 g / t of sodium oleate are added successively. The scheelite is recovered at room temperature through one roughing, four concentrating and three scavenging, wherein 100 g / t, 50 g / t and 20 g / t of sodium oleate are added to scavenging I, scavenging II and scavenging III respectively, 200 g / t and 100 g / t of water glass are added to concentrating I and concentrating II respectively, and no reagent is added to concentrating III and concentrating IV, to obtain scheelite concentrate and concentrating tailings; ③ The pH value of the mixed tailings slurry containing fluorite and calcite (the mass concentration of the flotation slurry is 30%) is adjusted to 4 with sulfuric acid, and 200 g / t of acidified water glass and 300 g / t of octadecylamine are added again. After one roughing, six concentrating and two scavenging, fluorite concentrate is obtained, wherein 100 g / t and 50 g / t of octadecylamine are added to scavenging I and scavenging II respectively, 100 g / t and 50 g / t of acidified water glass are added to refining I and refining II respectively, and no drugs are added to refining III, refining IV, refining V and refining VI, to obtain fluorite concentrate and tailings containing calcite.

[0055] Example 2 The method for synthesizing the carboxymethyl-phosphorylated bifunctional chitosan inhibitor described in Example 2 is composed of the following steps: (1) Acid activation pretreatment: chitosan powder (chitosan with a deacetylation degree of 95% and a molecular weight of 50 kDa) was mixed with a 1 wt % citric acid aqueous solution at a mass ratio of 1:15, and stirred at 60 °C for 60 min to obtain an activated chitosan dispersion; (2) Phosphorylation reaction: sodium dihydrogen phosphate was added to the activated chitosan dispersion, the mass ratio of sodium dihydrogen phosphate to chitosan dispersion was 0.5:1, and 0.5 wt% of magnesium sulfate was added as a catalyst. The reaction was carried out in a 90°C water bath for 2 hours to obtain phosphorylated chitosan. (3) Carboxymethylation modification: Sodium chloroacetate was added to the phosphorylated chitosan, and then sodium hydroxide was added to adjust the pH of the reaction system to 8. The mass ratio of phosphorylated chitosan, sodium chloroacetate and sodium hydroxide was 1:0.5:1.5. The reaction was stirred at 65 °C for 4 hours to generate carboxymethyl-phosphorylated bifunctional chitosan. (4) Solid-liquid separation and drying: The carboxymethyl-phosphorylated bifunctional chitosan obtained above was precipitated with ethanol at a mass ratio of 4:1 to carboxymethyl-phosphorylated bifunctional chitosan. The chitosan was washed with a 4:1 ethanol-water mixture for 20 min and a 0.2 mol / L NaOH solution for 10 min, and then dried (vacuum drying was used at a drying temperature of 60°C for 12 h) to obtain the carboxymethyl-phosphorylated chitosan inhibitor.

[0056] The application of the carboxymethyl-phosphorylated bifunctional chitosan inhibitor described in Example 2 for flotation separation of scheelite, fluorite and calcite consists of the following steps: ①Using a tungsten mine in Jiangxi, the ore contains WO 3 The grade is 0.546%, CaF 2 The grade is 32.17%, CaCO 3 The grade is 18.97%. The ore is ground to -0.074 mm, accounting for 50%. Then, sodium carbonate is added to adjust the pH of the pulp (the mass concentration of the flotation pulp is 45%) to 9, and 300 g / t of the carboxymethyl-phosphorylated bifunctional chitosan inhibitor prepared in Example 2 and 600 g / t of oleic acid are added successively. Scheelite is recovered through one roughing, two fine cleanings and three scavengings, wherein 300 g / t, 150 g / t and 60 g / t of oleic acid are added to Sweep I, Sweep II and Sweep III, respectively, and 100 g / t and 50 g / t of the carboxymethyl-phosphorylated bifunctional chitosan inhibitor prepared in Example 2 are added to Refinement I and Refinement II, respectively, to obtain scheelite concentrate and mixed tailings containing fluorite and calcite.

[0057] ② The pH value of the scheelite rough concentrate slurry (the mass concentration of the scheelite rough concentrate slurry is 20%) is adjusted to 9 with sodium carbonate, and 300 g / t of the carboxymethyl-phosphorylated bifunctional chitosan inhibitor prepared in Example 2 and 200 g / t of oleic acid are added successively. The scheelite is recovered by one roughing, three concentrating and two scavenging at room temperature, wherein 100 g / t and 50 g / t of oleic acid are added to scavenging I and scavenging II, respectively, and 150 g / t, 50 g / t and 20 g / t of the carboxymethyl-phosphorylated bifunctional chitosan inhibitor prepared in Example 2 are added to concentrating I, concentrating II and concentrating III, respectively, to obtain scheelite concentrate and concentrating tailings.

[0058] ③ The pH of the mixed tailings slurry containing fluorite and calcite (the mass concentration of the flotation slurry is 40%) is adjusted to 5 with hydrochloric acid, and 300 g / t of the carboxymethyl-phosphorylated bifunctional chitosan inhibitor prepared in Example 2 and 500 g / t of dodecylamine are added again. After one roughing, seven concentrating and two scavenging, fluorite concentrate is obtained, wherein 200 g / t and 10 g / t of dodecylamine are added to scavenging I and scavenging II, respectively, 100 g / t and 50 g / t of the carboxymethyl-phosphorylated bifunctional chitosan inhibitor prepared in Example 2 are added to refined I and refined II, respectively, and refined III, refined IV, refined V, refined VI and refined VII are not added with drugs to obtain fluorite concentrate and tailings containing calcite.

[0059] Comparative Example 7 The flotation separation method of scheelite, fluorite and calcite described in this comparative example 7 is composed of the following steps: ①Using a tungsten mine in Jiangxi, the ore contains WO 3 The grade is 0.546%, CaF 2 The grade is 32.17%, CaCO 3 The grade is 18.97%. The ore is ground to -0.074 mm, accounting for 50%. Then, sodium carbonate is added to adjust the pH of the pulp (the mass concentration of the flotation pulp is 45%) to 9, and 300g / t of water glass and 600g / t of oleic acid are added successively. Scheelite is recovered through one roughing, two fine cleanings and three scavengings. Among them, 300g / t, 150g / t and 60g / t of oleic acid are added to scavenging I, scavenging II and scavenging III respectively, and 100g / t and 50g / t of water glass are added to fine I and fine II respectively, to obtain scheelite concentrate and mixed tailings containing fluorite and calcite.

[0060] ② The pH value of the scheelite rough concentrate slurry (the mass concentration of the scheelite rough concentrate slurry is 20%) is adjusted to 9 with sodium carbonate, and 300 g / t water glass and 200 g / t oleic acid are added successively. The scheelite is recovered in the slurry at 90°C through one roughing, three cleaning and two scavenging. Among them, 100 g / t and 50 g / t of oleic acid are added to scavenging I and scavenging II respectively, and 150 g / t, 50 g / t and 20 g / t of water glass are added to cleaning I, cleaning II and cleaning III respectively, to obtain scheelite concentrate and cleaned tailings.

[0061] ③ Use hydrochloric acid to adjust the pH value of the mixed tailings slurry containing fluorite and calcite (the mass concentration of the flotation slurry is 40%) to 5, and add 300g / t of acidified water glass and 500g / t of dodecylamine again. After one roughing, seven cleaning and two scavenging, fluorite concentrate is obtained, wherein 200g / t and 10g / t of dodecylamine are added to scavenging I and scavenging II respectively, 100g / t and 50g / t of acidified water glass are added to refining I and refining II respectively, and no drugs are added to refining III, refining IV, refining V, refining VI and refining VII, to obtain fluorite concentrate and tailings containing calcite.

[0062] Comparative Example 8 The flotation separation method of scheelite, fluorite and calcite described in this comparative example 8 consists of the following steps: ①Using a tungsten mine in Jiangxi, the ore contains WO 3 The grade is 0.546%, CaF 2 The grade is 32.17%, CaCO 3 The grade is 18.97%. The ore is ground to -0.074 mm, accounting for 50%. Then, sodium carbonate is added to adjust the pH of the pulp (the mass concentration of the flotation pulp is 45%) to 9, and 300g / t of water glass and 600g / t of oleic acid are added successively. Scheelite is recovered through one roughing, two fine cleanings and three scavengings. Among them, 300g / t, 150g / t and 60g / t of oleic acid are added to scavenging I, scavenging II and scavenging III respectively, and 100g / t and 50g / t of water glass are added to fine I and fine II respectively, to obtain scheelite concentrate and mixed tailings containing fluorite and calcite.

[0063] ② The pH value of the scheelite rough concentrate slurry (the mass concentration of the scheelite rough concentrate slurry is 20%) is adjusted to 9 with sodium carbonate, and 300 g / t water glass and 200 g / t oleic acid are added successively. The scheelite is recovered at room temperature through one roughing, three concentrating and two scavenging. Among them, 100 g / t and 50 g / t of oleic acid are added to scavenging I and scavenging II respectively, and 150 g / t, 50 g / t and 20 g / t of water glass are added to concentrating I, concentrating II and concentrating III respectively, to obtain scheelite concentrate and concentrating tailings.

[0064] ③ Use hydrochloric acid to adjust the pH value of the mixed tailings slurry containing fluorite and calcite (the mass concentration of the flotation slurry is 40%) to 5, and add 300g / t of acidified water glass and 500g / t of dodecylamine again. After one roughing, seven cleaning and two scavenging, fluorite concentrate is obtained, wherein 200g / t and 10g / t of dodecylamine are added to scavenging I and scavenging II respectively, 100g / t and 50g / t of acidified water glass are added to refining I and refining II respectively, and no drugs are added to refining III, refining IV, refining V, refining VI and refining VII, to obtain fluorite concentrate and tailings containing calcite.

[0065] Example 3 The method for synthesizing the carboxymethyl-phosphorylated bifunctional chitosan inhibitor described in Example 3 is composed of the following steps: (1) Acid activation pretreatment: chitosan powder (chitosan with a deacetylation degree of 85% and a molecular weight of 200 kDa) was mixed with a 3 wt % citric acid aqueous solution at a mass ratio of 1:10 and stirred at 40 °C for 30 minutes to obtain an activated chitosan dispersion; (2) Phosphorylation reaction: trisodium phosphate was added to the activated chitosan dispersion, with the mass ratio of trisodium phosphate to chitosan dispersion being 3:1. At the same time, 2 wt% magnesium sulfate was added as a catalyst, and the mixture was reacted in a water bath at 85°C for 3 hours to obtain phosphorylated chitosan. (3) Carboxymethylation modification: Sodium chloroacetate was added to the phosphorylated chitosan, and then sodium hydroxide was added to adjust the pH of the reaction system to 7.5. The mass ratio of phosphorylated chitosan, sodium chloroacetate and sodium hydroxide was 1:3:0.3. The reaction was stirred at 50 °C for 6 hours to generate carboxymethyl-phosphorylated bifunctional chitosan. (4) Solid-liquid separation and drying: The carboxymethyl-phosphorylated bifunctional chitosan obtained above was precipitated with ethanol at a mass ratio of ethanol to carboxymethyl-phosphorylated bifunctional chitosan of 4:1, and then washed with a mixed solution of ethanol and water at a volume ratio of 2:1 for 5 min and a 0.4 mol / L NaOH solution for 30 min, and dried (vacuum drying was used at a drying temperature of 40°C for a drying time of 24 h) to obtain the carboxymethyl-phosphorylated chitosan inhibitor.

[0066] The application of the carboxymethyl-phosphorylated bifunctional chitosan inhibitor described in Example 3 for flotation separation of scheelite, fluorite and calcite consists of the following steps: ①Using a tungsten mine in Henan, the ore contains WO 3 The grade is 0.428%, CaF 2 The grade is 28.17%, CaCO 3The grade is 22.92%. The ore is ground to -0.074 mm, accounting for 95%. Then, sodium hydroxide is added to adjust the pH of the slurry (the mass concentration of the flotation slurry is 25%) to 10, and 100 g / t of the carboxymethyl-phosphorylated bifunctional chitosan inhibitor prepared in Example 3, 200 g / t of sodium dodecyl sulfate and 100 g / t of sodium dodecyl sulfonate are added successively. Scheelite is recovered through one roughing, three fine cleanings and three scavengings, wherein 100 g / t, 50 g / t and 20 g / t of sodium dodecyl sulfate and 50 g / t, 20 g / t and 10 g / t of sodium dodecyl sulfonate are added to scavenging I, scavenging II and scavenging III, respectively, and 50 g / t and 20 g / t of the carboxymethyl-phosphorylated bifunctional chitosan inhibitor prepared in Example 3 are added to fine I and fine II, respectively, to obtain scheelite concentrate and mixed tailings containing fluorite and calcite, and no drug is added to fine III.

[0067] ② The pH of the scheelite rough concentrate slurry (the mass concentration of the scheelite rough concentrate slurry is 10%) is adjusted to 10 with sodium hydroxide, and 100 g / t of the carboxymethyl-phosphorylated bifunctional chitosan inhibitor prepared in Example 3 and 100 g / t of sodium dodecyl sulfate are added successively. The scheelite is recovered by one roughing, three concentrating and two scavenging at room temperature, wherein 50 g / t and 20 g / t of sodium dodecyl sulfate are added to scavenging I and scavenging II, respectively, and 50 g / t, 20 g / t and 10 g / t of the carboxymethyl-phosphorylated bifunctional chitosan inhibitor prepared in Example 3 are added to concentrating I, concentrating II and concentrating III, respectively, to obtain scheelite concentrate and concentrating tailings.

[0068] ③ The pH of the mixed tailings slurry containing fluorite and calcite (the mass concentration of the flotation slurry is 20%) is adjusted to 6 with oxalic acid, and 500 g / t of the carboxymethyl-phosphorylated bifunctional chitosan inhibitor prepared in Example 3 and 100 g / t of etheramine are added again. After one roughing, six cleanings and two scavengings, fluorite concentrate is obtained, wherein 50 g / t and 20 g / t of etheramine are added to scavenging I and scavenging II, respectively, 200 g / t and 100 g / t of the carboxymethyl-phosphorylated bifunctional chitosan inhibitor prepared in Example 3 are added to refining I and refining II, respectively, and no drug is added to refining III, refining IV, refining V and refining VI, to obtain fluorite concentrate and tailings containing calcite.

[0069] Comparative Example 9 The flotation separation method of scheelite, fluorite and calcite described in this comparative example 9 consists of the following steps: ①Using a tungsten mine in Henan, the ore contains WO 3 The grade is 0.428%, CaF 2 The grade is 28.17%, CaCO 3The grade is 22.92%. The ore is ground to -0.074 mm, accounting for 95%. Then, sodium hydroxide is added to adjust the pH of the pulp (the mass concentration of the flotation pulp is 25%) to 10, and 100g / t of water glass, 200g / t of sodium dodecyl sulfate and 100g / t of sodium dodecyl sulfonate are added successively. Scheelite is recovered through one roughing, three fine cleanings and three scavengings. Among them, 100g / t, 50g / t and 20g / t of sodium dodecyl sulfate and 50g / t, 20g / t and 10g / t of sodium dodecyl sulfonate are added to scavenging I, scavenging II and scavenging III respectively, and 50g / t and 20g / t of water glass are added to fine I and fine II respectively, to obtain scheelite concentrate and mixed tailings containing fluorite and calcite, and no medicine is added to fine III.

[0070] ② Adjust the pH value of the scheelite rough concentrate slurry (the mass concentration of the scheelite rough concentrate slurry is 10%) to 10 with sodium hydroxide, add 100g / t water glass and 100g / t sodium dodecyl sulfate successively, and recover the scheelite in the slurry at 90℃ through one roughing, three cleaning and two scavenging, wherein 50g / t and 20g / t sodium dodecyl sulfate are added to scavenging I and scavenging II respectively, and 50g / t, 20g / t and 10g / t water glass are added to cleaning I, cleaning II and cleaning III respectively, to obtain scheelite concentrate and cleaned tailings.

[0071] ③ The pH value of the mixed tailings slurry containing fluorite and calcite (the mass concentration of flotation slurry is 20%) is adjusted to 6 with oxalic acid, and 500 g / t of acidified water glass and 100 g / t of ether amine are added again. After one roughing, six cleaning and two scavenging, fluorite concentrate is obtained, wherein 50 g / t and 20 g / t of ether amine are added to scavenging I and scavenging II respectively, 200 g / t and 100 g / t of acidified water glass are added to refining I and refining II respectively, and no drugs are added to refining III, refining IV, refining V and refining VI, to obtain fluorite concentrate and tailings containing calcite.

[0072] Comparative Example 10 The flotation separation method of scheelite, fluorite and calcite described in this comparative example 10 is composed of the following steps: ①Using a tungsten mine in Henan, the ore contains WO 3 The grade is 0.428%, CaF 2 The grade is 28.17%, CaCO 3The grade is 22.92%. The ore is ground to -0.074 mm, accounting for 95%. Then, sodium hydroxide is added to adjust the pH of the pulp (the mass concentration of the flotation pulp is 25%) to 10, and 100g / t of water glass, 200g / t of sodium dodecyl sulfate and 100g / t of sodium dodecyl sulfonate are added successively. Scheelite is recovered through one roughing, three fine cleanings and three scavengings. Among them, 100g / t, 50g / t and 20g / t of sodium dodecyl sulfate and 50g / t, 20g / t and 10g / t of sodium dodecyl sulfonate are added to scavenging I, scavenging II and scavenging III respectively, and 50g / t and 20g / t of water glass are added to fine I and fine II respectively, to obtain scheelite concentrate and mixed tailings containing fluorite and calcite, and no medicine is added to fine III.

[0073] ② The pH value of the scheelite rough concentrate slurry (the mass concentration of the scheelite rough concentrate slurry is 10%) is adjusted to 10 with sodium hydroxide, and 100 g / t of water glass and 100 g / t of sodium dodecyl sulfate are added successively. The scheelite is recovered at room temperature through one roughing, three concentrating and two scavenging. Among them, 50 g / t and 20 g / t of sodium dodecyl sulfate are added to scavenging I and scavenging II respectively, and 50 g / t, 20 g / t and 10 g / t of water glass are added to concentrating I, concentrating II and concentrating III respectively, to obtain scheelite concentrate and concentrating tailings.

[0074] ③ The pH value of the mixed tailings slurry containing fluorite and calcite (the mass concentration of flotation slurry is 20%) is adjusted to 6 with oxalic acid, and 500 g / t of acidified water glass and 100 g / t of ether amine are added again. After one roughing, six cleaning and two scavenging, fluorite concentrate is obtained, wherein 50 g / t and 20 g / t of ether amine are added to scavenging I and scavenging II respectively, 200 g / t and 100 g / t of acidified water glass are added to refining I and refining II respectively, and no drugs are added to refining III, refining IV, refining V and refining VI, to obtain fluorite concentrate and tailings containing calcite.

[0075] The comparison of the flotation effects of Example 1 and Comparative Examples 1-5 is summarized, and the main flotation indicators are listed in Table 1.

[0076] Table 1 Flotation test results of Example 1 and Comparative Examples 1-6

[0077] Table 2 Flotation test results of Example 2 and Comparative Examples 7-8

[0078] Table 3 Flotation test results of Example 3 and Comparative Examples 9-10

[0079] From the data obtained from the flotation test in Table 1-3, we can know that: (1) The chitosan used in Comparative Example 1 was not pretreated with citric acid, but was directly diluted and phosphorylated and carboxymethylated. The flotation test results showed that only WO 3 Tungsten concentrate with a grade of 35.12% and a recovery rate of 67.56%, as well as CaF 2 The fluorite concentrate with a grade of 87.22% and a recovery rate of 64.27% has a lower grade and recovery rate than the carboxymethyl-phosphorylated bifunctional chitosan inhibitor obtained in Example 1, in which chitosan is activated with citric acid and then phosphorylated and carboxymethyl-modified. This indicates that citric acid pickling can open the crystallization area, expose more hydroxyl and amino active sites, provide pre-activated sites for subsequent phosphorylation reactions, enhance the uniformity of phosphate substitution, and thus improve the selectivity of the inhibitor.

[0080] (2) In the synthesis process of Comparative Example 2, the carboxymethylation modification of chitosan was omitted. The experimental results show that only WO 3 Tungsten concentrate with a grade of 37.28% and a recovery rate of 64.68%, as well as CaF 2 The fluorite concentrate with a grade of 85.37% and a recovery rate of 66.98% is lower in both grade and recovery rate than the carboxymethyl-phosphorylated bifunctional chitosan inhibitor obtained in Example 1 with carboxymethyl modification. Under alkaline conditions, the carboxymethyl group is ionized to -CH 2 COO ‒ , can be combined with WO on the surface of scheelite 4 2‒ Produce electrostatic repulsion, reduce non-target adsorption, and competitively bind to calcite's CO 3 2‒ , amplifying the difference in mineral surface charge and enhancing pH responsiveness.

[0081] (3) The phosphorylation reaction was omitted in the synthesis process of Comparative Example 3. The test results show that only WO 3 Tungsten concentrate with a grade of 41.05% and a recovery rate of 56.59%, as well as CaF 2 The fluorite concentrate with a grade of 85.69% and a recovery rate of 65.11% is lower in both concentrate grade and recovery rate than the carboxymethyl-phosphorylated bifunctional chitosan inhibitor obtained in Example 1 for phosphorylation reaction. The phosphate group is ionized to -PO under alkaline conditions. 3 2‒ , with Ca in fluorite and calcite 2+ Form a five-membered ring chelate. In addition, the step ionization of the phosphate group (pKa1≈2.1, pKa2≈7.2, pKa3≈12.3) gives it a wide pH range adaptability: pH 8-10: with -PO 3 2‒ Targeted inhibition of fluorite / calcite; pH 4-6: with -PO 3 H‒ Preferentially binds to active Ca in calcite 2+ Therefore, phosphorylation will greatly enhance the selectivity and pH responsiveness of the inhibitor.

[0082] (4) In the synthesis process of Comparative Example 4, carboxylation reaction was first performed and then phosphorylation reaction was performed. The flotation test results show that only WO 3 Tungsten concentrate with a grade of 45.66% and a recovery rate of 66.39%, as well as CaF 2 The fluorite concentrate with a grade of 88.67% and a recovery rate of 62.04% has a lower grade and recovery rate than the carboxymethyl-phosphorylated bifunctional chitosan inhibitor obtained in Example 1, which is first subjected to phosphorylation and then to carboxymethylation modification. Since sodium chloroacetate is added during the carboxymethylation reaction, it will compete with the phosphate group, resulting in the inability to introduce the carboxymethyl group into the remaining C6 hydroxyl site, resulting in a steric hindrance effect, which reduces the selectivity of the inhibitor.

[0083] (5) Comparative Examples 5, 7 and 9 used conventional fluorite and calcite flotation depressants, water glass and acidified water glass, and carried out scheelite concentration in a slurry environment heated to 90°C. The results showed that the grade and recovery rate of scheelite and fluorite concentrates obtained in Comparative Examples 5, 7 and 9 were lower than those of the carboxymethyl-phosphorylated bifunctional chitosan depressant obtained in Examples 1, 2 and 3. This indicates that the carboxymethyl-phosphorylated bifunctional chitosan depressant developed by the present invention can achieve efficient separation of scheelite, fluorite and calcite in the flotation process at room temperature.

[0084] (6) Comparative Examples 6, 8 and 10 used conventional fluorite and calcite flotation inhibitors, water glass and acidified water glass, and carried out scheelite concentration in a slurry environment at room temperature. The results showed that the grade and recovery rate of scheelite and fluorite concentrate obtained in Comparative Examples 6, 8 and 10 were lower than those of the carboxymethyl-phosphorylated bifunctional chitosan inhibitor obtained in Examples 1, 2 and 3, as well as Comparative Examples 5, 7 and 9. This indicates that conventional flotation agents must be heated to ensure a certain flotation selectivity during scheelite concentration, further highlighting the advanced nature of the carboxymethyl-phosphorylated bifunctional chitosan inhibitor obtained in the present invention.

Claims

1. A method for synthesizing a carboxymethyl-phosphorylated bifunctional chitosan inhibitor, characterized in that: It consists of the following steps: (1) Acid activation pretreatment The chitosan powder and the citric acid aqueous solution are uniformly mixed and stirred to react to prepare an activated chitosan dispersion; (2) Phosphorylation reaction Add phosphate and magnesium sulfate to the activated chitosan dispersion prepared in step (1), and react at 80-90° C. for 2-4 hours to prepare phosphorylated chitosan; (3) Carboxymethylation Adding sodium chloroacetate to the phosphorylated chitosan prepared in step (2), then adding sodium hydroxide to adjust the pH value of the reaction system to 7-8, and stirring the reaction to generate carboxymethyl-phosphorylated bifunctional chitosan; (4) Solid-liquid separation and drying The carboxymethyl-phosphorylated bifunctional chitosan prepared in step (3) is precipitated with ethanol, then washed with an ethanol-water mixture and a NaOH solution in sequence, and dried to obtain a carboxymethyl-phosphorylated bifunctional chitosan inhibitor.

2. The method for synthesizing the carboxymethyl-phosphorylated bifunctional chitosan inhibitor according to claim 1, characterized in that: The chitosan powder in step (1) has a deacetylation degree of 85%-95% and a molecular weight of 50-200 kDa; In step (1), the mass concentration of the citric acid aqueous solution is 1-3wt%, and the mass ratio of the chitosan powder to the citric acid aqueous solution is 1:10-1:15; In step (1), the stirring and mixing temperature is 40-60° C., and the stirring and mixing time is 30-60 min.

3. The method for synthesizing the carboxymethyl-phosphorylated bifunctional chitosan inhibitor according to claim 1, characterized in that: The phosphate in step (2) is one of disodium hydrogen phosphate, sodium dihydrogen phosphate or trisodium phosphate; In step (2), the mass ratio of phosphate to activated chitosan dispersion is 0.5:1-3:1, the mass of magnesium sulfate accounts for 0.5-2wt% of the mass of phosphate, and magnesium sulfate serves as a catalyst for the phosphorylation reaction.

4. The method for synthesizing the carboxymethyl-phosphorylated bifunctional chitosan inhibitor according to claim 1, characterized in that: In step (3), the mass ratio of phosphorylated chitosan, sodium chloroacetate and sodium hydroxide is 1:0.5-3:0.3-1.5; The stirring reaction temperature in step (3) is 50-80° C., and the stirring reaction time is 2-6 h.

5. The method for synthesizing the carboxymethyl-phosphorylated bifunctional chitosan inhibitor according to claim 1, characterized in that: In step (4), the mass ratio of ethanol to carboxymethyl-phosphorylated bifunctional chitosan is 4:1; The volume ratio of ethanol to water in the ethanol-water mixture in step (4) is 4:1-2:1, and the washing time is 5-20 minutes; The concentration of the NaOH solution in step (4) is 0.2-0.4 mol / L, and the washing time is 10-30 min; In step (4), vacuum drying is used for drying, the drying temperature is 40-60°C, and the drying time is 12-24h.

6. An application of a carboxymethyl-phosphorylated bifunctional chitosan inhibitor, characterized in that: Used for flotation separation of scheelite, fluorite and calcite, it consists of the following steps: ① Grind the ore containing scheelite, fluorite and calcite to -0.074 mm, accounting for 50%-95%, then adjust the pH value of the slurry to 8-10, add carboxymethyl-phosphorylated bifunctional chitosan inhibitor and anion collector successively, and obtain scheelite rough concentrate and mixed tailings containing fluorite and calcite through one roughing, multiple cleaning and multiple sweeping; ② adjusting the pH value of the scheelite rough concentrate slurry prepared in step ① to 8-10, adding a carboxymethyl-phosphorylated bifunctional chitosan inhibitor and an anion collector, and subjecting the scheelite concentrate and the concentrated tailings to one roughing, multiple concentrating and multiple scavenging at room temperature; ③ The pH value of the mixed tailings slurry containing fluorite and calcite prepared in step ① is adjusted to 4-6, a carboxymethyl-phosphorylated bifunctional chitosan inhibitor and a cationic collector are added, and fluorite concentrate and calcite-containing tailings are obtained through one roughing, multiple cleaning and multiple scavenging.

7. The use of the carboxymethyl-phosphorylated bifunctional chitosan inhibitor according to claim 6, characterized in that: The mass concentration of the flotation pulp in step ① is 25%-45%; In step ①, sodium hydroxide or sodium carbonate is added to adjust the pH value of the slurry to 8-10; In step ①, the amount of the carboxymethyl-phosphorylated bifunctional chitosan inhibitor is 100-500 g / t, and the anion collector is at least one of sodium oleate, oleic acid, sodium dodecyl sulfate or sodium dodecyl sulfonate, and the amount is 300-1000 g / t; The number of times of concentrating in step ① is 2-3 times, and the carboxymethyl-phosphorylated bifunctional chitosan inhibitor is added in the flotation and concentrating operation of the scheelite, and the amount used is 1 / 4-1 / 2 of the previous operation; The number of scavenging in step ① is 3 times, and anion collector is added in the flotation scavenging operation of scheelite, and the amount used is 1 / 4-1 / 2 of the previous operation.

8. The use of the carboxymethyl-phosphorylated bifunctional chitosan inhibitor according to claim 6, characterized in that: In step ②, the mass concentration of the scheelite coarse concentrate slurry is 10%-20%; In step ②, the amount of carboxymethyl-phosphorylated bifunctional chitosan inhibitor is 100 g / t-500 g / t, and the anion collector is at least one of sodium oleate, oleic acid, sodium dodecyl sulfate or sodium dodecyl sulfonate, and the amount is 100 g / t-200 g / t; In step ②, the number of selections is 3-4 times, and the number of scans is 2-3 times.

9. The use of the carboxymethyl-phosphorylated bifunctional chitosan inhibitor according to claim 6, characterized in that: The mass concentration of the flotation pulp in step ③ is 20%-40%; In step ③, one of sulfuric acid, hydrochloric acid or oxalic acid is added to adjust the pH value of the slurry to 4-6.

10. The use of the carboxymethyl-phosphorylated bifunctional chitosan inhibitor according to claim 6, characterized in that: In step ③, the dosage of the carboxymethyl-phosphorylated bifunctional chitosan inhibitor is 200-500 g / t, and the cationic collector is at least one of dodecylamine, octadecylamine or etheramine collectors, and the dosage is 100-500 g / t; In step ③, the number of selections is 6-7 times, and the number of scans is 2 times.

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