ALKYL THIOETHER ETHYL HYDROXAMIC ACID BENEFICIATION REAGENT AND PREPARATION METHOD AND APPLICATION THEREOF

Abstract

An alkyl thioether ethyl hydroxamic acid beneficiation reagent and a preparation method and application thereof are provided. The alkyl thioether ethyl hydroxamic acid molecules have two functional groups, a thioether group and a hydroxamate group. The beneficiation reagent is obtained by esterification of alkyl thioether acetic acid and methanol and then by hydroxamation of hydroxylamine and an alkali. The alkyl thioether ethyl hydroxamic acid beneficiation reagent can be used as a collector for mineral flotation. The preparation method is simple and has a high yield. The thioether and hydroxamate group in the molecules have a synergistic effect and can effectively improve the collection performance.

Claims

1. An alkyl thioether ethyl hydroxamic acid beneficiation reagent, wherein the alkyl thioether ethyl hydroxamic acid beneficiation reagent has a structure as shown in formula I, ##STR00004## wherein in the formula I, R.sup.1 is one selected from the group consisting of a C.sub.1-C.sub.12 alkane group, a C.sub.5-C.sub.12 cycloalkyl group, a C.sub.6-C.sub.12 aromatic group and a C.sub.1-C.sub.12 alkane group and the C.sub.1-C.sub.12 alkane group is substituted with at least one substituent.

2. The alkyl thioether ethyl hydroxamic acid beneficiation reagent according to claim 1, wherein R.sup.1 is one selected from the group consisting of methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, sec-pentyl, neopentyl, cyclopentyl, n-hexyl, isohexyl, sec-hexyl, cyclohexyl, heptyl, cycloheptyl, n-octyl, isooctyl, sec-octyl, cyclooctyl, benzyl, phenyl, p-tert-butyl benzyl and dodecyl.

3. The alkyl thioether ethyl hydroxamic acid beneficiation reagent according to claim 2, wherein R.sup.1 is the benzyl or the dodecyl.

4. A preparation method of the alkyl thioether ethyl hydroxamic acid beneficiation reagent according to claim 1, comprising the following steps: (1) an esterification reaction: subjecting an alkyl thioether acetic acid with a structure as shown in formula II and methanol to the esterification reaction under a catalysis of a concentrated sulfuric acid to obtain a methyl alkyl thioether acetate with a structure as shown in formula III; ##STR00005## (2) a hydroxamation reaction: subjecting the methyl alkyl thioether acetate with the structure as shown in the formula III, a hydroxylamine and an alkali to the hydroxamation reaction in an aqueous solution to obtain the alkyl thioether ethyl hydroxamic acid beneficiation reagent, ##STR00006##

5. The preparation method according to claim 4, wherein in step (1), a temperature of the esterification reaction is 50-100° C., a reaction time is 1-6 hours, a molar ratio of the alkyl thioether acetic acid to the methanol is 1:(1-8), a mass fraction of the concentrated sulfuric acid is 25-50 g/mol, and an added amount of the concentrated sulfuric acid is 2.5-5 g/0.1 mol of the alkyl thioether acetic acid.

6. The preparation method according to claim 4, wherein in step (2), a temperature of the hydroxamation reaction is 10-60° C., a reaction time is 2.5-6 hours, the hydroxylamine is hydroxylamine hydrochloride or hydroxylamine sulfate, the alkali is sodium hydroxide or potassium hydroxide, a molar ratio of the methyl alkyl thioether acetate to the hydroxylamine to the alkali is 1:(1-1.5):(1-1.5), and an amount of water in the aqueous solution is 10-100 mL water/0.1 mol of the methyl alkyl thioether acetate.

7. A method of collecting a flotation of metallic ores, comprising: using the alkyl thioether ethyl hydroxamic acid beneficiation reagent according to claim 1 as a collector for the flotation of the metallic ores.

8. The method according to claim 7, wherein the metallic ores are at least one selected from the group consisting of bauxite, tungsten ores, copper oxide ores and tin ores.

9. The method according to claim 7, wherein a basic process of using the alkyl thioether ethyl hydroxamic acid beneficiation reagent as the collector comprises: (1) floating the metallic ores after grinding to achieve the flotation of the metallic ores; (2) preparing a saline solution of the alkyl thioether ethyl hydroxamic acid as a flotation reagent by mixing the alkyl thioether ethyl hydroxamic acid beneficiation reagent and sodium hydroxide or potassium hydroxide in water; (3) adding hydrochloric acid or the sodium hydroxide during the floating to adjust a pulp pH to 7-9, and adding the saline solution of the alkyl thioether ethyl hydroxamic acid to the flotation of the metallic ores under weakly alkaline conditions to reach a concentration of 25-400 mg/L; and (4) floating useful metallic minerals by a froth flotation method.

10. The preparation method according to claim 4, wherein R.sup.1 is one selected from the group consisting of methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, sec-pentyl, neopentyl, cyclopentyl, n-hexyl, isohexyl, sec-hexyl, cyclohexyl, heptyl, cycloheptyl, n-octyl, isooctyl, sec-octyl, cyclooctyl, benzyl, phenyl, p-tert-butyl benzyl and dodecyl.

11. The preparation method according to claim 10, wherein R.sup.1 is the benzyl or the dodecyl.

12. The method according to claim 7, wherein R.sup.1 is one selected from the group consisting of methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, sec-pentyl, neopentyl, cyclopentyl, n-hexyl, isohexyl, sec-hexyl, cyclohexyl, heptyl, cycloheptyl, n-octyl, isooctyl, sec-octyl, cyclooctyl, benzyl, phenyl, p-tert-butyl benzyl and dodecyl.

13. The method according to claim 12, wherein R.sup.1 is the benzyl or the dodecyl.

14. The method according to claim 8, wherein a basic process of using the alkyl thioether ethyl hydroxamic acid beneficiation reagent as the collector comprises: (1) floating the metallic ores after grinding to achieve the flotation of the metallic ores: (2) preparing a saline solution of the alkyl thioether ethyl hydroxamic acid as a flotation reagent by mixing the alkyl thioether ethyl hydroxamic acid beneficiation reagent and sodium hydroxide or potassium hydroxide in water; (3) adding hydrochloric acid or the sodium hydroxide during the floating to adjust a pulp pH to 7-9, and adding the saline solution of the alkyl thioether ethyl hydroxamic acid to the flotation of the metallic ores under weakly alkaline conditions to reach a concentration of 25-400 mg/L; and (4) floating useful metallic minerals by a froth flotation method.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] FIG. 1 is a nuclear magnetic resonance hydrogen spectrum of 2-(benzylthio)-acetohydroxamic acid;

[0033] FIG. 2 is a nuclear magnetic resonance carbon spectrum of 2-(benzylthio)-acetohydroxamic acid;

[0034] FIG. 3 is an infrared spectrum of 2-(benzylthio)-acetohydroxamic acid;

[0035] FIG. 4 is a nuclear magnetic resonance hydrogen spectrum of 2-(dodecylthio)-acetohydroxamic acid;

[0036] FIG. 5 is a nuclear magnetic resonance carbon spectrum of 2-(dodecylthio)-acetohydroxamic acid;

[0037] FIG. 6 shows the optimal configuration of 2-(benzylthio)-acetohydroxamic acid at the level of DFT/B3LYP6-311G(d);

[0038] FIG. 7 shows the optimal configuration of benzohydroxamic acid at the level of DFT/B3LYP6-311G(d);

[0039] FIG. 8 shows the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of 2-(benzylthio)-acetohydroxamic acid at the level of DFT/B3LYP6-311 G(d);

[0040] FIG. 9 shows the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of benzohydroxamic acid at the level of DFT/B3LYP6-311G(d);

[0041] FIG. 10 shows the molecular electrostatic potential of 2-(benzylthio)-acetohydroxamic acid at the level of DFT/B3LYP6-311G(d);

[0042] FIG. 11 shows the molecular electrostatic potential of benzohydroxamic acid at the level of DFT/B3LYP6-311G(d);

[0043] FIG. 12 is a schematic diagram of molecular structure and atomic numbers of benzohydroxamic acid and 2-(benzylthio)-acetohydroxamic acid;

[0044] FIG. 13 is a flowchart of a wolframite flotation process in Example 6 of the present invention.

DETAILED DESCRIPTION

[0045] The present invention is further described with reference to the following examples, but is not limited by these examples.

Example 1

[0046] Preparation of 2-(Benzylthio)-Acetohydroxamic Acid:

[0047] For the first step, 18.93 g of 96.15% 2-(benzylthio)acetic acid, 16.16 g of 99% methanol and 2.5 g of 98% concentrated sulfuric acid were added to a 150 mL three-neck flask. After the mixture was heated at 75° C. for 5 hours, the temperature was cooled to room temperature. Then, 4.2 g of 98.5% solid sodium bicarbonate was added, the mixture was filtered and distilled under reduced pressure to remove methanol to obtain methyl S-benzylthioglycolate. For the second step, 7.76 g of 99.5% hydroxylamine hydrochloride and 30 mL distilled water were added to a 150 mL three-neck flask. Under stirring, 8.33 g of 85.0% sodium hydroxide and 20 mL distilled water were added to the mixture in batches, under 5° C. heat. Next, methyl S-benzylthioglycolate was added dropwise to the mixture. After a reaction time of 4 h at 40° C., the mixture was acidified with sulfuric acid to obtain 16.81 g product of 2-(benzylthio)-acetohydroxamic acid with a yield of 91.86% based on 2-(benzylthio)acetic acid. 2-(benzylthio)-acetohydroxamic acid was characterized after purification, with .sup.1H NMR, .sup.13C NMR and infrared spectrum being as shown in FIGS. 1 to 3 respectively.

TABLE-US-00001 TABLE 1 Analysis results of nuclear magnetic resonance hydrogen spectrum and carbon spectrum Compound NMR 2-(benzylthio)-acetohydroxamic .sup.1H NMR/δ δ: 2.91(2H, —CH2—), 3.83(2H, —CH2—), acid (the solvent is deuterated 7.25(5H, —C6H5), 8.93(1H, —NH—), DMSO) 10.58(—OH) .sup.13C NMR/δ δ: 31.66(1C, S—CH2—), 36.13(1C, —CH2—S), 127.41(1C, Ar—CH); 128,88(2C, 2Ar—CH); 129.44(2C, Ar—CH); 138.47(1C, CH); 166.41(1C, C═O).

TABLE-US-00002 TABLE 2 Analysis results of infrared spectrum Compound Peak shift and possible attribution 2-(benzylthio)-acetohydroxamic 3247 cm.sup.−1 is —OH or —NH stretching vibration; 3055 and acid 302.3 cm.sup.−1 are C═CH—H stretching vibration on a benzene ring; 2975 and 2925 cm.sup.−1 are —CH.sub.2— stretching vibration; 1641 cm.sup.−1 is C═O stretching vibration; 1519 cm.sup.−1 is C—N stretching vibration; 910 cm.sup.−1 is C—S stretching vibration; 702 cm.sup.−1 is benzene ring bending vibration.

[0048] Quantum chemistry calculation results show that a hydrophobic constant ClogP value of 2-(benzylthio)-acetohydroxamic acid is 0.9626, energy values of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of molecules are −0.24699 and −0.03267 respectively. An energy gap between the highest occupied molecular orbital and the lowest unoccupied molecular orbital can be used as a stability index for organic compounds. The energy gap of 2-(benzylthio)-acetohydroxamic acid is 0.21432, which is close to the benzohydroxamic acid (Table 3). As a result, 2-(benzylthio)-acetohydroxamic acid has high collection ability and good selectivity and is especially suitable for flotation of copper oxide ores, bauxite, tungsten ores, tin ores and other oxide minerals.

[0049] It can be seen from Table 4 and FIG. 10 that the N—O bond length of 2-(benzylthio)-acetohydroxamic acid is similar to that of benzohydroxamic acid, but the C═O double bond is longer. It indicates that electrons of 2-(benzylthio)-acetohydroxamic acid are less distributed between the C═O double bonds, which results in weaker strength of the C═O double bonds than benzohydroxamic acid, and therefore the activity is higher. Hydroxamic acid interacts with minerals through combination of two O atoms in carbonyl and hydroxyl groups and metal cations to form a five-membered ring structure. Therefore, 2-(benzylthio)-acetohydroxamic acid is more likely to interact with metal cations. Dihedral angle data show that the dihedral angle composed of 2-(benzylthio)-acetohydroxamic acid O4-C3-N2-O1 is closer to 0 than benzohydroxamic acid, which is conducive to formation of conjugated n bonds, improving the effect of metal ions with the minerals and facilitating a more stable chelating ring after interacting with metal ions.

TABLE-US-00003 TABLE 3 Single-point energy, HOMO and LUMO energy values and CLogP value of the hydroxamic acid collector at the level of DFT/B3LYP6-311G(d) HOMO- HOMO LUMO LUMO Energy E.sub.T Collector (a.u.) (a.u.) (a.u.) (a.u.) ClogP Benzohydroxamic acid −0.27071 −0.05732 0.21339 −476.24628 0.255 2-(benzylthio)-acetohydroxamic −0.24699 −0.03267 0.21432 −953.10377 0.9626 acid

TABLE-US-00004 TABLE 4 Structural parameters of the benzohydroxamic acid collector at the level of DFT/B3LYP6-311G(d) r1 r2 r3 α1 α2 τ Collector (O1-N2) (N2-C3) (C3-O4) (O1-N2-C3) (N2-C3-O4) (O4-C3-N2-O1) 2-(benzylthio)- 1.39 1.34 1.24 118.59 120.42 6.54566 acetohydroxamic acid Bertzollydroxamic acid 1.39 1.38 1.22 117.49 122.93 −13.17814

Example 2

[0050] Preparation of 2-(Benzylthio)-Acetohydroxamic Acid:

[0051] For the first step, 9.47 g of 96.15% 2-(benzylthio)acetic acid, 8.08 g of 99% methanol and 1.3 g of 98% concentrated sulfuric acid were added to a 100 mL three-neck flask. After the mixture was heated at 75° C. for 5 hours, the temperature was cooled to room temperature. Then, 2.1 g of 98.5% solid sodium bicarbonate was added, the mixture was filtered and distilled under reduced pressure to remove methanol to obtain methyl S-benzylthioglycolate. For the second step, 3.88 g of 99.5% hydroxylamine hydrochloride and 30 mL distilled water were added to a 100 mL three-neck flask. Under stirring, 6.59 g of 85.0% sodium hydroxide and 20 mL distilled water were added to the mixture in batches, under 5° C. heat. Next, methyl S-benzylthioglycolate was added dropwise to the mixture. After a reaction time of 4 h at 40° C., the mixture was acidified with sulfuric acid to obtain 8.92 g product of 2-(benzylthio)-acetohydroxamic acid with a yield of 90.56% based on 2-(benzylthio)acetic acid. Example 3

[0052] Preparation of 2-(Dodecylthio)-Acetohydroxamic Acid:

[0053] For the first step, 18.71 g of 97.30% 2-(dodecylthio)acetic acid, 16.16 g of 99%/6 methanol and 2.5 g of 98% concentrated sulfuric acid were added to a 150 mL three-neck flask. After the mixture was heated at 75° C. for 4.5 hours, the temperature was cooled to room temperature. Then, 4.2 g of 98.5% solid sodium bicarbonate was added, the mixture was filtered and distilled under reduced pressure to remove methanol to obtain methyl S-dodecylthioglycolate. For the second step, 7.76 g of 99.5% hydroxylamine hydrochloride and 30 mL distilled water were added to a 150 mL three-neck flask. Under stirring, 8.33 g of 85.0% sodium hydroxide and 20 mL distilled water were added to the mixture in batches, under 5° C. heat. Next, methyl S-dodecylthioglycolate was added dropwise to the mixture. After a reaction time of 4 h at 40° C., the mixture was acidified with sulfuric acid to obtain 17.20 g product of 2-(dodecylthio)-acetohydroxamic acid with a yield of 89.30% based on 2-(dodecylthio)acetic acid, with .sup.1H NMR and .sup.13C NMR being as shown in FIGS. 4 to 5 respectively.

TABLE-US-00005 TABLE 5 Analysis results of nuclear magnetic resonance hydrogen spectrum and carbon spectrum Compound NMR 2-(dodecylthio)-acetohydroxamic .sup.1H NMR/δ δ: 0.84-0.87(3H, —CH3), 1.24-1.31 acid (the solvent is deuterated (16H, —CH2—), 1.31-1.35(2H, —CH2—), DMSO) 1.48-1.55(2H, —CH2—), 2.54-2.61 (2H, —CH2—), 3.20(2H, —CH2—), 3.63(1H, —NH—), 10.55(—OH) .sup.13C NMR/δ δ: 14.43(1C, —CH3), 19.53(1C, —CH2—), 22.57(1C, —CH2—), 28.79(1C, —CH2—), 29.19(1C, —CH2—), 29.28(1C, —CH2—), 29,44(1C, —CH2—), 29.49(1C, —CH2—), 29,52(1C, —CH2—), 31.77(1C, —CH2—), 31.98(1C, —CH2—), 33.45(1C, —CH2—), 35.48(1C, —CH2—), 165.53(1C, C═O).

Example 4

[0054] Flotation of Malachite with 2-(Benzylthio)-Acetohydroxamic Acid:

[0055] The concentration of 2-(benzylthio)-acetohydroxamic acid and benzohydroxamic acid was 400 mg/L, the pulp pH was 8, the concentration of a foaming agent (MIBC) was 30 mg/L and the rotation speed was 1650 r/min, malachite with the particle size of −0.076 mm to +0.038 mm was subjected to flotation for 5 minutes respectively. When 2-(benzylthio)-acetohydroxamic acid was used as a collector, 96.26% of malachite can float out, while when benzohydroxamic acid was used as a collector, only 30.88% of malachite can float out.

Example 5

[0056] Flotation of Bauxite with 2-(Benzylthio)-Acetohydroxamic Acid:

[0057] The concentration of 2-(benzylthio)-acetohydroxamic acid and benzohydroxamic acid was 150 mg/L, the pulp pH was 8, the concentration of a foaming agent (MIBC) was 30 mg/L and the rotation speed was 1650 r/min, bauxite with the particle size of −0.076 mm to +0.038 mm was subjected to flotation for 5 minutes respectively. When 2-(benzylthio)-acetohydroxamic acid was used as a collector, 95.91% of bauxite can float out, while when benzohydroxamic acid was used as a collector, only 19.88% of bauxite can float out.

Example 6

[0058] Flotation of Wolframite with 2-(Benzylthio)-Acetohydroxamic Acid:

[0059] The concentration of 2-(benzylthio)-acetohydroxamic acid and benzohydroxamic acid was 25 mg/L, the pulp pH was 8, the concentration of an activator (Pb.sup.2+) was 30 mg/L, the concentration of a foaming agent (MIBC) was 30 mg/L and the rotation speed was 1650 r/min, wolframite with the particle size of −0.076 mm to +0.038 mm was subjected to flotation for 5 minutes respectively. The flowchart of the flotation process was as shown in FIG. 10. When 2-(benzylthio)-acetohydroxamic acid was used as a collector, 95.89% of wolframite can float out, while when benzohydroxamic acid was used as a collector, only 46.86% of wolframite can float out.

Example 7

[0060] Flotation of Cassiterite with 2-(Benzylthio)-Acetohydroxamic Acid

[0061] The concentration of 2-(benzylthio)-acetohydroxamic acid and benzohydroxamic acid was 400 mg/L, the pulp pH was 8, the concentration of a foaming agent (MIBC) was 30 mg/L and the rotation speed was 1650 r/min, cassiterite with the particle size of −0.076 mm to +0.038 mm was subjected to flotation for 5 minutes respectively. When 2-(benzylthio)-acetohydroxamic acid was used as a collector, 79.41% of cassiterite can float out, while when benzohydroxamic acid was used as a collector, only 42.83% of cassiterite can float out.