CN104801426A - Schiff base caproate mineral flotation collecting agent as well as preparation method and application thereof - Google Patents

Abstract

The invention discloses a Schiff base caproate mineral flotation collecting agent, a preparation method thereof and application thereof. A Schiff base caproate has an aliphatic group and a carbon-nitrogen double bond and carboxyl structure and is prepared by performing ammonia aldehyde condensation reaction on hydrolyzed caprolactam and aliphatic aldehyde. The Schiff base caproate has the characteristics of good water solubility, high dispersibility and high selective adsorption capacity to a target mineral, serves as the flotation collecting agent of bauxite, ilmenite, scheelite, wolframite, rare earth mine, tin ore, fluorite ore or manganese carbonate ore, and can effectively float and separate available minerals; furthermore, the preparation method of the Schiff base caproate is simple in process, easy in control on operation, low in cost, and high in product yield, and industrial production is easy to realize.

Description

A Schiff base hexanoate mineral flotation collector and its preparation method and application

technical field

The invention relates to a Schiff base hexanoate mineral flotation collector and a preparation method and application thereof, belonging to the field of mineral flotation.

Background technique

Fatty acids and their soaps, because they contain active carboxyl functional groups, can effectively separate useful minerals from gangue, and are a class of excellent non-sulfide ore flotation collectors. Since higher fatty acids are solid at room temperature, difficult to dissolve in water, and inconvenient to use, oleic acid, linoleic acid, linolenic acid, tall oil fatty acid and liquid saturated fatty acid are commonly used, and are currently the most commonly used in industrial flotation processes. It is oleic acid and its modified products and oxidized paraffin soap. Chinese patent (publication number is CN102921537A) discloses a kind of method of flotation limonite with oleic acid; The collector that forms is used for the method of ilmenite, iron oxide ore flotation; Sodium phosphate is used as the depressant of barite mineral, to the method for flotation separation of low-grade fluorite barite; A method for segmented flotation of a single type of fluorite ore with various impurities; Chinese patent (publication number CN103657860A) discloses a collector formed by interworking of oxidized paraffin wax soap and sodium dodecylsulfonate in acidic conditions The method for enriching zinc silicate minerals by lower flotation; Chinese patent (publication number is CN101648157 and CN101757983A) discloses a method for flotation of black and scheelite with mixed fatty acids including oleic acid; Chinese patent (publication number is CN102302982A) discloses a kind of beneficiation method of reclaiming scheelite from gneiss type ore; Chinese patent (publication number is CN102716811A) discloses the process of flotation of water-soluble weathered apatite ore with cotton oleic acid and rapeseed acid mixed acid Method; Chinese patent (publication number is CN102962144A) discloses a method for flotation bauxite with oleic acid with a saponification degree of about 50%.

As a collector, oleic acid is popular among mineral flotation manufacturers due to its strong collection ability and wide application range. Oxidized paraffin wax soap as a substitute for oleic acid has the advantages of cheap price and little influence on the flotation temperature of the pulp, but it also has disadvantages such as inferior flotation performance to oleic acid when used alone, poor selectivity, and low concentrate grade. . In view of different ore feeding properties, climate characteristics and the shortage of oleic acid and oxidized paraffin soap collectors, the development of new and efficient collectors has become one of the hot spots in the development of mineral processing technology.

At present, there are reports of amino acid Schiff bases, which are mainly made into metal complexes. These Schiff base metal complexes have good biological activity and catalytic activity, and can be used in the field of biomedicine or chemical catalysis. Amino acid Schiff bases are usually produced by the reaction of aldehydes or ketones with amino acids. They are particularly easy to hydrolyze and generally need to be synthesized under anhydrous conditions. Amino acid Schiff bases derived from aliphatic aldehydes or ketones are rarely reported due to their poor stability. European patent (publication number is WO 2008/127760A1) discloses a kind of preparation method of the amino acid Schiff base obtained by the reaction of n-octylaldehyde and lysine, but finds that this amino acid is unstable and will soon be reunited into Oil. Samy B.Said reported that the yield of Schiff base prepared by the reaction of aromatic ring-containing aldehyde and tert-butylamine is more than 80%, but when using aliphatic aldehyde (such as 2-ethyl-2-hexenal) and When tert-butylamine reacts to prepare the corresponding Schiff base, because the Schiff base is unstable and easily oxidized, the pure product (Samy B.Said, Jacek Mlochowski, Jacek Skariewski.Synthesis of 2- Alkyl-3-vinyloxaziridines as Potential Antitumor Agents. Liebigs Annalen der Chemie, 1990(5), 461-464.).

The research on amino acid Schiff bases is limited to amino acid Schiff bases containing aromatic rings (Formula 3), and this type of Schiff bases are mainly exhibited in the fields of medicine, catalysis, analytical chemistry, electrochemistry and magnetism. Good application prospect, but the preparation method of Schiff base fatty acid salt and the application as collector in flotation have not yet been reported.

Contents of the invention

Flotation collectors such as oleic acid and oxidized paraffin soaps in the prior art have defects such as low selectivity, poor frost resistance, and poor dispersibility. The purpose of the present invention is to provide a class of And Schiff base hexanoate with carbon-nitrogen double bond and carboxyl structure, which has good selective adsorption to non-sulfide minerals, good water solubility and good dispersibility, and can be used as a mineral flotation collector.

Another object of the present invention is to provide a method for preparing Schiff base hexanoate mineral flotation collectors with simple process, easy operation control, low cost and high yield.

Another object of the present invention is to provide the application of the Schiff base hexanoate mineral flotation collector, the Schiff base hexanoate has good water solubility and dispersibility, and is capable of collecting non-sulfide minerals Strong, good selectivity, suitable for flotation collection of various minerals.

In order to solve the defects in the prior art, the invention provides a Schiff base hexanoate mineral flotation collector, which has a structure of formula 1:

in,

R is a C ₃ -C ₁₁ alkane group or alkene group;

M is Na ⁺ or K ⁺ .

In the preferred Schiff base hexanoate mineral flotation collector, R is a _C7 alkane group or alkene group.

In the preferred Schiff base hexanoate mineral flotation collector, R is a _C7 linear or branched alkane group or a _C7 monoalkene group.

In the most preferred Schiff base hexanoate mineral flotation collector, R is n-heptyl, 1-ethyl-n-pentyl or 1-ethyl-1,2-pentenyl.

The Schiff base caproic acid salt of the invention has imine group and carboxylic acid at the same time, and the imine group and carboxyl group have synergistic chelation and adsorption effect on the target element on the mineral surface, greatly increasing the collection ability of the target mineral. The preferred Schiff base hexanoate mineral flotation collector has carboxyl groups and aliphatic groups with appropriate lengths, which is more conducive to improving its hydrophilicity and dispersion performance in the flotation collection process.

The present invention also provides a method for preparing Schiff base caproate mineral flotation collectors. Caprolactam is hydrolyzed and ring-opened in a sodium hydroxide and/or potassium hydroxide solution at a temperature of 80-105°C to obtain Aminocaproic acid salt; the aminocaproic acid salt and the aldehyde compound having the structure of formula 2 are subjected to an aminoaldehyde condensation reaction at a temperature of 90 to 120°C under acid catalysis to obtain the product;

in,

R is a C ₃ -C ₁₁ alkane or alkene group.

In a preferred scheme, R is a _C7 alkane group or an alkene group; more preferably a _C7 straight-chain or branched alkane group or a _C7 monoalkene group; most preferably n-heptyl, 1-ethyl n-pentyl or 1-ethyl-1,2-pentenyl.

In a preferred scheme, the molar ratio of sodium hydroxide and/or potassium hydroxide to water in the potassium hydroxide and/or sodium hydroxide solution is 1:1˜1:2.

In a preferred scheme, the molar ratio of potassium hydroxide and/or sodium hydroxide to caprolactam is 1:1.

In a preferred scheme, a water-carrying agent or a water-absorbing agent is added to the amaldehyde condensation reaction to remove the water generated by the amaldehyde condensation reaction.

In a more preferred solution, the water-carrying agent is at least one of benzene, toluene, and chloroform. In the present invention, water-carrying agent is added in the process of ammonia-aldehyde condensation reaction, and after the reaction is completed, the azeotrope of water and water-carrying agent is removed by vacuum distillation.

In a more preferred solution, the water-absorbing agent is at least one of anhydrous potassium carbonate, anhydrous magnesium sulfate, anhydrous sodium sulfate, anhydrous calcium chloride, and 4A molecular sieve. In the present invention, a water-absorbing agent is added during the ammonia-aldehyde condensation reaction, and after the reaction is completed, the water-absorbing agent is filtered while hot to remove the water-absorbing agent.

In a preferred solution, the acid catalyst is at least one of concentrated sulfuric acid, concentrated hydrochloric acid, glacial acetic acid, and p-toluenesulfonic acid.

In a preferred scheme, the time for the hydrolysis and ring-opening reaction is 0.5-3 hours.

In a preferred scheme, the time for the aminoaldehyde condensation reaction is 2 to 5 hours.

In a preferred scheme, the molar ratio of the aldehyde compound to the aminocaproic acid salt is 1:1˜1.3:1.

In a preferred scheme, the aminocaproic acid salt is added slowly or in batches to the aldehyde compound for reaction.

The caprolactam used in the present invention is a commercially available conventional raw material, which is preheated and melted during use, and then potassium hydroxide and/or sodium hydroxide solution is added to carry out the hydrolysis reaction.

The preparation method of Schiff base hexanoate mineral flotation collector of the present invention comprises the following specific steps:

(1) Hydrolysis and ring-opening reaction of caprolactam: Add caprolactam into the reaction vessel, raise the temperature of the reactor to above 80°C to melt the caprolactam into a liquid, and add sodium hydroxide and/or potassium hydroxide solution into the liquid caprolactam , maintain the temperature at 80-105°C for 0.5-3 hours, and cool to room temperature to obtain light yellow solid sodium 6-aminocaproate and/or potassium 6-aminocaproate; among them, sodium hydroxide and/or hydrogen The molar ratio of potassium oxide to caprolactam is 1:1; the molar ratio of sodium hydroxide and/or potassium hydroxide to water is 1:1~1:2;

(2) Aminoaldehyde condensation reaction of 6-aminocaproic acid salt and aldehyde compound: add aldehyde compound, acid catalyst and water-carrying agent or water-absorbing agent in sequence in the reaction vessel, and add solid 6- Sodium aminocaproate, after the feeding is completed, react at 90-120°C for 2-5 hours, and the molar ratio of aldehydes to aminocaproate is 1:1-1.3:1;

(3) Post-treatment: If a water-absorbing agent is used, after the ammonia aldehyde condensation reaction is completed, filter the water-absorbing agent while it is hot, and after cooling to room temperature, a solid substance is precipitated, and the solid substance is washed with acetone and anhydrous ether for 2 to 3 times, Vacuum drying can obtain the Schiff base hexanoate mineral flotation collector; if a water-carrying agent is used, after the amaldehyde condensation reaction is completed, the water-carrying agent is removed by distillation under reduced pressure, and a solid substance is precipitated. Wash the solid matter with ether for 2 to 3 times, and dry to obtain the Schiff base hexanoate mineral flotation collector.

The present invention also provides the application of the Schiff base hexanoate mineral flotation collector, which is to apply the Schiff base hexanoate mineral flotation collector to bauxite, ilmenite, scheelite Flotation separation of useful minerals in ore, wolframite, rare earth ore, tin ore, fluorite ore or manganese carbonate ore.

In the preferred application method, during the ore grinding process or in the flotation process after grinding, flotation agents including Schiff base hexanoate mineral flotation collectors are added to adjust the slurry, and the foam Useful minerals are separated by flotation; among them, Schiff base hexanoate mineral collectors are added at a ratio of 50 to 1600g/t of ore.

In a more preferred application method, the pH of the ore slurry is maintained in the range of 6-12 during froth flotation.

In a more preferred application method, the ore with a particle size of -200 mesh in the ore slurry accounts for 50% to 90% of the mass of the entire ore.

The Schiff base caproic acid salt of the invention can be used alone as a collector, or used in combination with other flotation agents.

Compared with the prior art, the present invention has beneficial effects: the present invention obtains for the first time a Schiff base hexanoate having both imino and carboxyl groups and an aliphatic chain structure. Its imine group and carboxyl group have a synergistic chelation and adsorption effect on metal ions on the mineral surface, greatly increasing the ability to collect target minerals; and the carboxyl group and the aliphatic hydrocarbon group of suitable length are more conducive to improving its hydrophilicity and floatation. Dispersion performance during election harvesting. The Schiff base hexanoate is used as a flotation collector for mineral flotation, and has the characteristics of good selectivity, strong collection capacity, good dispersibility and water solubility, and the like. Compared with the deficiencies such as poor antifreeze ability and poor dispersibility of conventional fatty acid agents in the prior art, the Schiff base caproic acid salt of the present invention has excellent water solubility, which is beneficial to the dissolution of the agent in the pulp, is convenient to use, and can be Widely used in flotation collection of non-sulfide ores, especially for flotation collection of bauxite, ilmenite, scheelite, wolframite, rare earth ore, tin ore, fluorite ore, manganese carbonate ore and other minerals . More importantly, the Schiff base caproic acid salt of the present invention is easily hydrolyzed into fatty aldehyde and 6-amino caproic acid salt in acidic medium, which makes it easy to carry out drug removal treatment on minerals after flotation. In addition, the preparation method of Schiff base caproic acid salt has simple process, easy operation control and low cost.

Description of drawings

[Fig. 1] is the infrared spectrogram of 6-(2-ethyl-2-enhexyl) imidocaproic acid sodium.

[Fig. 2] is the proton nuclear magnetic resonance spectrum of 6-(2-ethyl-2-enhexyl) imidocaproic acid sodium.

[Fig. 3] is a flow chart of the primary roughing of fluorite by sodium 6-(2-ethyl-2-enhexyl)iminocaproate.

[Fig. 4] is a process flow chart of primary roughing ilmenite for 6-(2-ethyl-2-enhexyl) sodium iminohexanoate.

[Fig. 5] is a process flow diagram of flotation of scheelite by sodium 6-(2-ethyl-2-enhexyl)iminocaproate.

[Fig. 6] is a process flow diagram of 6-(2-ethyl-2-enhexyl) sodium iminocaproate flotation bauxite.

[Fig. 7] is the process flow diagram of 6-(2-ethyl-2-enhexyl) sodium iminocaproate flotation manganese carbonate ore.

Detailed ways

The following examples are intended to further illustrate the present invention, but not to further limit the protection scope of the present invention.

All parts and percentages in Examples 1-12 refer to mass unless otherwise specified.

Example 1

Preparation of sodium 6-(2-ethyl-2-enhexyl)iminocaproate:

Add 5.66 parts of caprolactam into the reactor with a stirring device, melt it at a temperature of 80°C, and dissolve 2 parts of solid sodium hydroxide in 3 parts of distilled water to make an alkali solution, and add the alkali solution Into the melted caprolactam liquid, raise the temperature to 100°C, stir for 2 hours, and the white solid precipitated after cooling to room temperature is sodium 6-aminocaproate.

In the reactor, add 7.56 parts of 2-ethyl-2-hexenal, 0.48 parts of p-toluenesulfonic acid, 60 parts of toluene and the 6-aminocaproic acid sodium obtained by the above-mentioned hydrolysis, and install the water separator. React for 3 hours at a reaction temperature of 115°C. After removing the toluene by distillation under reduced pressure, the solid was washed twice with anhydrous ether and acetone in turn, and the obtained orange-red solid was dried in a vacuum dryer at 50°C for 24 hours to obtain 11.82 parts of solid , and the yield was 90.57%. Fig. 1 is the infrared spectrogram of the product, and Fig. 2 is the proton nuclear magnetic resonance spectrogram of the product.

Example 2

Preparation of sodium 6-(2-ethyl-2-enhexyl)iminocaproate:

Add 11.32 parts of caprolactam into the reactor with a stirring device, melt it at a temperature of 80°C, and dissolve 4 parts of solid sodium hydroxide in 6 parts of distilled water to make an alkali solution, and add the alkali solution to Into the melted caprolactam liquid, raise the temperature to 100°C, stir for 2 hours, and the white solid precipitated after cooling to room temperature is sodium 6-aminocaproate.

In the reactor, add 15.12 parts of 2-ethyl-2-hexenal, 0.95 parts of p-toluenesulfonic acid, 80 parts of toluene and the 6-aminocaproic acid sodium obtained by the above-mentioned hydrolysis successively, install the water separator, React for 4 hours at a reaction temperature of 115°C. After toluene was removed by distillation under reduced pressure, the solid was washed twice with anhydrous ether and acetone in turn, and the obtained orange-red solid was dried in a vacuum dryer at 50°C for 24 hours to obtain 23.82 parts of solid. , and the yield was 91.26%.

Example 3

Preparation of sodium n-octyliminocaproate:

Add 11.32 parts of caprolactam into the reactor with a stirring device, melt it at a temperature of 80°C, and dissolve 4 parts of solid sodium hydroxide in 6 parts of distilled water to make an alkali solution, and add the alkali solution to Into the melted caprolactam liquid, raise the temperature to 100°C, stir for 2 hours, and the white solid precipitated after cooling to room temperature is sodium 6-aminocaproate.

Add 15.12 parts of n-octanal, 0.95 parts of p-toluenesulfonic acid, and 80 parts of toluene to the reactor in sequence, and drop the molten sodium 6-aminocaproate liquid prepared by the above hydrolysis at 100°C. After the addition is completed, Install a water separator, react at a reaction temperature of 115°C for 4 hours, and distill off the toluene under reduced pressure, wash the solid twice with anhydrous ether and acetone in turn, and dry the obtained yellow solid in a vacuum dryer at 50°C for 24 hours , 25.65 parts of solid were obtained, and the yield was 97.53%.

Example 4

Preparation of 6-(2-ethylhexyl)iminocaproic acid sodium:

Add 5.66 parts of caprolactam into the reactor with a stirring device, melt it at a temperature of 80°C, and dissolve 2 parts of solid sodium hydroxide in 3 parts of distilled water to make an alkali solution, and add the alkali solution Into the melted caprolactam liquid, raise the temperature to 100°C, stir for 2 hours, and the white solid precipitated after cooling to room temperature is sodium 6-aminocaproate.

In the reactor, add 7.68 parts of 2-ethylhexanal, 0.48 parts of p-toluenesulfonic acid, 45 parts of toluene and the 6-aminocaproic acid sodium obtained by the above-mentioned hydrolysis successively, install a water separator, and the reaction temperature is The reaction was carried out at 115°C for 4h, after the toluene was distilled off under reduced pressure, the solid was washed twice with anhydrous ether and acetone in turn, and the obtained pale yellow solid was dried in a vacuum dryer at 50°C for 24h to obtain 10.82 parts of solid, with a yield of 82.28%.

The Schiff base hexanoate prepared in Examples 1 to 4 is compared with the front orbital energy of the conventional sodium oleate flotation agent in the prior art:

According to the molecular design theory of collectors, Schiff base hexanoate has stronger selective collection ability than oleate. Using the Gaussian 03 software, the B3LYP method of density functional theory and the 6-31G(d) basis set were used to calculate the frontier orbital energies of the Schiff base sodium hexanoate and sodium oleate. The results are shown in Table 1. As can be seen from Table 1, the highest occupied orbital (HOMO) energy of sodium oleate is about 4kJ/mol higher than the HOMO energy of Schiff base sodium hexanoate, indicating that sodium oleate has a slightly stronger ability to provide electrons to transition metal elements; However, the lowest unoccupied orbital (LUMO) energy of Schiff base sodium hexanoate is more than 100kJ/mol lower than that of sodium oleate LUMO, indicating that Schiff base sodium caproate is more likely to accept d orbital electrons of transition metal atoms to form feedback than sodium oleate The π bond is beneficial to enhance the coordination selectivity of Schiff base sodium hexanoate to transition metal elements.

Table 1 Comparison of frontier orbital energies of collector molecules

Example 5

Application of sodium 6-(2-ethyl-2-enhexyl)iminocaproate in fluorite flotation:

The CaF ₂ grade of a certain fluorite ore is 38.92%, and the ore is ground to -200 mesh, accounting for 60%. It is placed in a flotation tank, and the dosage of sodium carbonate is 1400g/t, the dosage of water glass is 400g/t, and the dosage of collector is 500g/t. , a roughing operation is carried out under the condition of flotation temperature of 30°C, and the flotation process flow chart is shown in Figure 3. 6-(2-ethyl-2-enhexyl) sodium iminocaproate collector among the present invention and the flotation comparison experiment result of commonly used sodium oleate collector are shown in Table 2. It can be seen from the table that when the flotation temperature is 30°C, the flotation recovery rate of sodium 6-(2-ethyl-2-enhexyl)iminocaproate to fluorite is 1.89 percentage points higher than that of traditional sodium oleate. CaF ₂ grade increased by 0.53 percentage points.

Table 2 Comparison experiment results of collector flotation fluorite when the flotation temperature is 30°C

Collector dosage (g/t raw ore) Coarse concentrate CaF ₂ grade (%) CaF ₂ recovery rate (%) Sodium Oleate 500 80.88 96.05 Sodium 6-(2-ethyl-2-enhexyl)iminocaproate 500 81.41 97.94

Example 6

Application of sodium 6-(2-ethyl-2-enhexyl)iminocaproate in ilmenite flotation:

An ilmenite raw ore with a _TiO2 grade of 22.85%, 60% of which is ground to -200 mesh, is placed in a flotation cell, and the sulfuric acid dosage is 1800g/t, the collector dosage is 1500g/t, and the flotation temperature is 30°C Next, a roughing operation is carried out, and the flow chart of the flotation process is shown in accompanying drawing 4. 6-(2-ethyl-2-enhexyl) sodium iminocaproate collector among the present invention and the flotation comparison experiment result of commonly used sodium oleate collector are shown in Table 3. It can be seen from the table that when the flotation temperature is 30°C, the flotation recovery rate of 6-(2-ethyl-2-enhexyl)iminocaproic acid sodium to ilmenite is 2.01 percentage points higher than that of traditional sodium oleate , TiO ₂ grade increased by 0.63 percentage points.

Table 3 Comparison experiment results of collector flotation ilmenite when the flotation temperature is 30°C

Example 7

Application of sodium 6-(2-ethyl-2-enhexyl)iminocaproate in scheelite flotation:

The tungsten grade of a certain scheelite ore is WO ₃ 0.47%, and the ore is ground to -200 mesh, accounting for 80%. 36g foaming agent No. 2 oil, and then add 3000g sodium carbonate, 2500g water glass, and 500g collector for scheelite roughing operation per ton of ore, and add 100g of collector for each ton of ore for sweeping, once selected Add 500g of water glass per ton of ore, and add 300g of water glass per ton of ore for secondary selection. The flow chart of the flotation process is shown in Figure 5. The flotation comparison experiment results of 6-(2-ethyl-2-enhexyl) sodium iminocaproate collector and commonly used oxidized paraffin wax soap 731 in the present invention are shown in Table 4. It can be seen from the table that the flotation recovery rate of 6-(2-ethyl-2-enhexyl)iminohexanoate to scheelite is 3.35 percentage points higher than that of traditional oxidized paraffin wax soap 731, and the WO ₃ grade is increased by 0.39 percentage points .

Table 4 Comparative experimental results of collector flotation scheelite

Example 8

Application of sodium 6-(2-ethyl-2-enhexyl)iminocaproate in bauxite flotation:

A certain bauxite contains 65.15% Al ₂ O ₃ , 10.27% SiO ₂ , 80% of which is ground to -200 mesh, placed in a flotation cell, the dosage of sodium carbonate is 4000g/t, and the dosage of sodium hexametaphosphate is 60g/t , 6-(2-ethyl-2-enhexyl) sodium iminocaproate or sodium oleate combined with sodium benzohydroxamic acid to carry out a roughing operation on bauxite under the condition of a collector dosage of 1000g/t , to obtain coarse aluminum concentrate, the flow chart of the flotation process is shown in Figure 6, and the flotation results are shown in Table 5. As can be seen from the table, compared with the combined use of sodium oleate and sodium benzohydroxamic acid, 6-(2-ethyl-2-enhexyl) iminocaproic acid sodium and sodium benzohydroxamic acid have a significant effect on After primary roughing of bauxite, the recovery rate of Al ₂ O ₃ increased by 3.10 percentage points, and the ratio of aluminum to silicon increased by 0.57.

Table 56-(2-Ethyl-2-enhexyl) sodium iminocaproate flotation bauxite comparison experiment results

Example 9

Application of sodium 6-(2-ethyl-2-enhexyl)iminocaproate in flotation of manganese carbonate ore:

The manganese grade of magnetic separation tailings of a manganese carbonate ore is 7.58%, and the ore is ground to -200 mesh, accounting for 80%. For roughing, 3000g sodium carbonate, 2500g water glass, and 1000g collector are added for each ton of ore, and for sweeping, the ore is fed per ton. Add 500g of water glass and 200g of collector, add 500g of water glass per ton of ore for the first beneficiation, and add 300g of water glass per ton of ore for the second beneficiation. The flotation process flow chart is shown in Figure 7. 6-(2-ethyl-2-enhexyl) sodium iminocaproate collector among the present invention and the flotation comparison experiment result of commonly used sodium oleate collector are shown in Table 6. As can be seen from the table, the flotation recovery rate of 6-(2-ethyl-2-enhexyl)iminohexanoate to manganese carbonate ore is increased by 1.78 percentage points compared with sodium oleate, and the concentrate manganese grade is improved by 1.69 percentage points.

Table 6 Flotation comparison experiment results of manganese carbonate magnetic separation tailings

Collector type Manganese grade in concentrate (%) Manganese recovery rate (%) sodium oleate 16.56 80.62

Sodium 6-(2-ethyl-2-enhexyl)iminocaproate 18.25 82.40

Claims (10)

1. A Schiff base caproate mineral flotation collector is characterized by having a structure shown in formula 1:

wherein,

r is C₃～C₁₁An alkyl or alkenyl group of (a);

m is Na⁺Or K⁺。

2. The Schiff base caproate mineral flotation collector of claim 1, wherein R is C₇An alkyl group or an alkenyl group.

3. The schiff base caproate mineral flotation collector of claim 2, wherein R is n-heptyl, 1-ethyl-n-pentyl, or 1-ethyl-1, 2-pentenyl.

4. The preparation method of the Schiff base caproate mineral flotation collector of claim 1, characterized in that caprolactam is subjected to hydrolysis ring-opening reaction in sodium hydroxide and/or potassium hydroxide solution at the temperature of 80-105 ℃ to obtain amino caproate; carrying out an amino-aldehyde condensation reaction on the amino caproate and an aldehyde compound with a structure shown in a formula 2 at a temperature of 90-120 ℃ under the catalysis of acid to obtain the amino caproate;

wherein,

r is C₃～C₁₁An alkyl group or an alkenyl group.

5. The method according to claim 4, wherein the molar ratio of sodium hydroxide and/or potassium hydroxide to water in the potassium hydroxide and/or sodium hydroxide solution is 1: 1-1: 2; the molar ratio of potassium hydroxide and/or sodium hydroxide to caprolactam is 1: 1.

6. The method of claim 4, wherein a water-carrying agent or water-absorbing agent is added to the reaction for removing water produced by the reaction.

7. The method according to claim 6, wherein the water-carrying agent is at least one of benzene, toluene and chloroform; the water absorbent is at least one of anhydrous potassium carbonate, anhydrous magnesium sulfate, anhydrous sodium sulfate, anhydrous calcium chloride and a 4A molecular sieve.

8. The method of claim 4, wherein the acid catalyst is at least one of concentrated sulfuric acid, concentrated hydrochloric acid, glacial acetic acid, and p-toluenesulfonic acid; the time for the hydrolytic ring-opening reaction is 0.5-3 h; the time for the ammonia-aldehyde condensation reaction is 2-5 h.

9. The application of the Schiff base caproate mineral flotation collector disclosed by any one of claims 1 to 3, which is characterized by being applied to flotation separation of useful minerals in bauxite, ilmenite, scheelite, wolframite, rare earth ore, tin ore, fluorite ore or manganese carbonate ore.

10. The application of the method as claimed in claim 9, wherein a flotation agent including a Schiff base caproate mineral flotation collector is added to the ore during grinding or during flotation after grinding for size mixing, and the useful minerals are separated by flotation through a froth flotation method; wherein the Schiff base caproate flotation collecting agent is added according to the proportion of 50-1600 g/t ore.