Process for the preparation of a flotation depressant for talc purification

Abstract

The present application relates to the technical field of flotation, and discloses a preparation method of a flotation depressant for talc purification, which comprises the following steps: adding 1 epoxidized cellulose and ethanolamine phosphate into a solvent, performing ring-opening reaction, then adding sodium hydroxide aqueous solution and 2-chloroethyl phosphate, and performing substitution reaction to obtain the flotation depressant for talc purification.The flotation depressant prepared by the method has a cellulose base body, a large amount of phosphate groups are introduced, can form a strong adsorption effect with silicate minerals and magnesium minerals in talc, and the surface force between the phosphate groups and molybdenite is low, so that a large amount of phosphate cellulose is closely attached to the surface of talc, the hydrophilicity of talc is improved, the floatability is reduced, the flotation depressant can be used as a talc depressant, and the flotation of molybdenite and the purification and separation of talc are effectively realized.

Description

Technical Field

[0001] The present invention relates to the field of flotation technology, in particular to a method for preparing a flotation depressant for talc purification. Background Art

[0002] Molybdenum is an important metallic element with significant applications in metallurgy, chemical engineering, electronics, aerospace, and other fields. Molybdenum is primarily derived from molybdenite. Using flotation to treat molybdenite is an effective method for improving the grade of molybdenum concentrate. Talc is a common associated mineral in molybdenite, but due to its excellent floatability, it can enter the molybdenum concentrate during flotation, reducing its quality. Therefore, an inhibitor is needed to reduce the floatability of talc. Common inhibitors include polysaccharides, sodium hexametaphosphate, and lignin sulfonates. Chinese patent CN108499743B discloses a combined inhibitor for talc and other easily floatable gangue minerals and its use method. Using Na2SiO3, aluminum sulfate, dextrin, and carboxymethyl cellulose as inhibitors, the combined inhibitor achieves the separation and flotation of molybdenite from easily floatable gangue minerals such as talc and mica. However, the inhibitor's composition is relatively complex and does not significantly improve the recovery rate of molybdenite concentrate. Summary of the Invention

[0003] The present invention solves the problem that the existing inhibitors have poor flotation separation effects on molybdenite and talc.

[0004] The technical solution of the present invention is a method for preparing a flotation depressant for talc purification: (1) adding 100 parts by weight of cellulose to a 12-15% by weight aqueous sodium hydroxide solution, stirring for 18-24 hours, filtering, adding the cellulose to water for soaking and swelling, adding 700-740 parts by weight of epichlorohydrin, dropping a 25-30% by weight aqueous sodium hydroxide solution, stirring and reacting at 40-45° C. for 2-2.5 hours, filtering, washing with water and ethanol, and drying to obtain epoxidized cellulose. The structural formula is:

[0005] (2) 100 parts by weight of epoxidized cellulose is added to a solvent, and after stirring, 15-45 parts by weight of phosphoethanolamine (CAS registration number 1071-23-4) is added to carry out a ring-opening reaction. Then, an aqueous sodium hydroxide solution and 22-70 parts by weight of 2-chloroethylphosphoric acid (CAS registration number 16672-87-0) are added to carry out a substitution reaction. An aqueous sodium hydroxide solution is further added to neutralize the mixture. After stirring, the solution is poured into ethanol to precipitate a precipitate, which is filtered, washed with ethanol, and dried to obtain a flotation depressant for talc purification. The reaction formula is as follows:

[0006]

[0007] Preferably, the solvent in (2) is N,N-dimethylformamide or N,N-dimethylacetamide.

[0008] Preferably, the temperature of the ring-opening reaction in (2) is 70-85° C., and the reaction time is 10-18 h.

[0009] Preferably, the temperature of the substitution reaction in (2) is 45-75° C., and the reaction time is 12-24 h.

[0010] Preferably, the mass fraction of the sodium hydroxide aqueous solution in (2) is 5-30%.

[0011] Preferably, the flotation depressant for talc purification in (2) is used for flotation separation of molybdenite and talc.

[0012] The present invention has the following beneficial technical effects: The flotation depressant prepared by the present invention uses cellulose as a matrix and introduces a large number of phosphate groups, which can form a strong adsorption effect with silicate minerals and magnesium minerals in talc. The phosphate groups have a low surface interaction with molybdenite, allowing a large amount of phosphate cellulose to tightly adhere to the talc surface, improving the hydrophilicity of the talc and reducing its floatability. It can be used as a talc depressant, thereby achieving the flotation of molybdenite and the purification and separation of talc. Using conventional butyl xanthate as a capture agent and methyl isobutyl carbinol as a frother, the addition of phosphate cellulose significantly reduces the recovery rate and content of talc in the concentrate, thereby increasing the content and recovery rate of molybdenite in the concentrate, reaching a maximum of 97.15%. The recovery rate of talc in the tailings reaches as high as 93.7%, effectively achieving the flotation of molybdenite and the purification and separation of talc. DETAILED DESCRIPTION

[0013] In order to make the purpose, technical solutions and advantages of this application more clear, the present application is further described in detail below with reference to the embodiments. It should be understood that the embodiments described are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0014] Example 1

[0015] (1) Add 10 g of cellulose to 200 mL of a 15% by mass sodium hydroxide aqueous solution, stir for 18 h, filter, add the cellulose to water for soaking and swelling, add 70 g of epichlorohydrin, add dropwise 80 mL of a 30% by mass sodium hydroxide aqueous solution, stir and react at 40°C for 2.5 h, filter, wash with water and ethanol, and dry to obtain epoxidized cellulose.

[0016] (2) 10 g of epoxidized cellulose was added to 120 mL of N,N-dimethylacetamide, and 1.5 g of phosphoethanolamine was added after stirring. The mixture was heated to 75° C. and stirred for 12 h. Then, 20 mL of a 25% by mass sodium hydroxide aqueous solution and 2.2 g of 2-chloroethylphosphoric acid were added, and the mixture was stirred at 45° C. for 24 h. 10 mL of a 5% by mass sodium hydroxide aqueous solution was added for neutralization. After stirring, the solution was poured into ethanol to precipitate a precipitate, which was filtered, washed with ethanol, and dried to obtain a flotation depressant for talc purification.

[0017] Example 2

[0018] (1) Add 10 g of cellulose to 200 mL of a 12% sodium hydroxide aqueous solution, stir for 24 h, filter, add the cellulose to water for soaking and swelling, add 74 g of epichlorohydrin, dropwise add 100 mL of a 25% sodium hydroxide aqueous solution, stir and react at 45°C for 2 h, filter, wash with water and ethanol, and dry to obtain epoxidized cellulose.

[0019] (2) 10 g of epoxidized cellulose was added to 1300 mL of N,N-dimethylformamide, and 2.5 g of phosphoethanolamine was added after stirring. The mixture was heated to 70° C. and stirred for 18 h. Then, 22 mL of a 20% by mass sodium hydroxide aqueous solution and 4 g of 2-chloroethylphosphoric acid were added, and the mixture was stirred at 60° C. for 12 h. 8 mL of an 8% by mass sodium hydroxide aqueous solution was added for neutralization. After stirring, the solution was poured into ethanol to precipitate a precipitate, which was filtered, washed with ethanol, and dried to obtain a flotation depressant for talc purification.

[0020] Example 3

[0021] (1) 10 g of epoxidized cellulose (prepared in Example 1) was added to 150 mL of N,N-dimethylacetamide, and after stirring, 3.5 g of phosphoethanolamine was added. The mixture was heated to 85° C. and stirred for 10 h. Then, 20 mL of a 25% by mass sodium hydroxide aqueous solution and 5.5 g of 2-chloroethylphosphoric acid were added. The mixture was stirred at 60° C. for 18 h. 10 mL of a 5% by mass sodium hydroxide aqueous solution was added for neutralization. After stirring, the solution was poured into ethanol to precipitate a precipitate, which was filtered, washed with ethanol, and dried to obtain a flotation depressant for talc purification.

[0022] Example 4

[0023] (1) To 120 mL of N,N-dimethylacetamide, 10 g of epoxidized cellulose (prepared in Example 1) was added, after stirring, 1.5 g of ethanolamine phosphate was added, heated to 75°C, stirred for 12 h, then 20 mL of 25% by mass aqueous sodium hydroxide solution was added for neutralization, after stirring, the solution was poured into ethanol, the precipitate was separated, filtered, washed with ethanol, and dried to obtain a flotation depressant.

[0024] Comparative Example 1

[0025] (1) To 120 mL of N,N-dimethylacetamide, 10 g of epoxidized cellulose (prepared in Example 1) was added, after stirring, 1.5 g of ethanolamine phosphate was added, heated to 75°C, stirred for 12 h, then 20 mL of 25% by mass aqueous sodium hydroxide solution was added for neutralization, after stirring, the solution was poured into ethanol, the precipitate was separated, filtered, washed with ethanol, and dried to obtain a flotation depressant.

[0026] Comparative Example 2

[0027] Comparative Example 3

[0028] Flotation separation simulation test of molybdenite and talc: 1 g of molybdenite and 1 g of talc were ground and sieved, the particle size of -0.074 mm was 90%, added to a hanging tank flotation machine, 50 mL of distilled water was added, stirred for 2 min, the pH was adjusted to 5, the depressant (controlled amount 15 mg / L) was added, then the collector butyl xanthate (controlled amount 400 mg / L) was added, stirred for 3 min, then the frother methyl isobutyl carbinol (controlled amount 18 mg / L) was added, stirred for 2 min, then air was supplied for flotation and froth scraping, the products in the froth and the tank were collected, dried, and weighed to obtain the concentrate and the tailings, respectively. The grade of molybdenite and talc in the concentrate and the tailings was measured, and the recovery rate was calculated.

[0029] Recovery rate = (concentrate weight x concentrate grade) / (ore weight x ore grade) x 100%.

[0030] Table 1 Recovery rate test

[0031]

[0032] After testing, the conventional butyl xanthate of Examples 1-4 was used as a capture agent, methyl isobutyl carbinol as a foaming agent, and cellulose containing a phosphate group was added as a talc inhibitor, which significantly reduced the recovery rate and content of talc in the concentrate, thereby increasing the content and recovery rate of molybdenite in the concentrate, reaching a maximum of 97.15%. The recovery rate of talc in the tailings reached a maximum of 93.7%, effectively achieving the flotation of molybdenite and the purification and separation of talc. This is mainly because cellulose contains a large amount of phosphate groups, which can form a strong adsorption effect with silicate minerals and magnesium minerals in talc, and the phosphate groups have a low surface force on the molybdenite, so that a large amount of phosphate cellulose is closely attached to the surface of talc, improving the hydrophilicity of talc and reducing floatability, thereby achieving the flotation of molybdenite and the purification and separation of talc.

[0033] When comparative example 1 prepares inhibitor, 2-chloroethyl phosphoric acid is not added, resulting in that the phosphate group of cellulose contains less, and the reactive force with talcum surface is lower, there is no obvious reduction in the floatability of talcum, and the flotation, separation effect of talcum and molybdenite are relatively poor. The cellulose of comparative example 2 does not contain phosphate group, and it and talcum and molybdenite surface can form the interactions such as hydrogen bond, improve the hydrophilicity on talcum and molybdenite surface, reduce the floatability of the two, resulting in that the recovery of molybdenite in concentrate significantly decreases, and the flotation of molybdenite and the purification separation of talcum cannot be effectively realized. Comparative example 3 uses conventional sodium hexametaphosphate as inhibitor, and the recovery of molybdenite in concentrate after flotation is lower, and the recovery of talcum in tailings is explained, and the ability to suppress the floatability of talcum is relatively low.

Claims

1. A method for preparing a flotation depressant for talc purification, characterized in that: The preparation method comprises the following steps: adding 100 parts by weight of epoxidized cellulose to a solvent, stirring, adding 15-45 parts by weight of phosphoethanolamine to carry out a ring-opening reaction, then adding a sodium hydroxide aqueous solution and 22-70 parts by weight of 2-chloroethylphosphoric acid to carry out a substitution reaction, further adding a sodium hydroxide aqueous solution to neutralize, stirring, pouring the solution into ethanol to precipitate a precipitate, filtering, washing with ethanol, and drying to obtain a flotation depressant for talc purification.

2. The method for preparing a flotation depressant for talc purification according to claim 1, characterized in that: The solvent is N,N-dimethylformamide or N,N-dimethylacetamide.

3. The method for preparing a flotation depressant for talc purification according to claim 1, wherein: The temperature of the ring-opening reaction is 70-85° C., and the reaction time is 10-18 h.

4. The method for preparing a flotation depressant for talc purification according to claim 1, characterized in that: The temperature of the substitution reaction is 45-75° C., and the reaction time is 12-24 hours.

5. The method for preparing a flotation depressant for talc purification according to claim 1, characterized in that: The mass fraction of the sodium hydroxide aqueous solution is 5-30%.

6. The method for preparing a flotation depressant for talc purification according to claim 1, characterized in that: The preparation method of the epoxidized cellulose comprises the following steps: adding 100 parts by weight of cellulose to a 12-15% by weight aqueous sodium hydroxide solution, stirring for 18-24 hours, filtering, adding the cellulose to water for soaking and swelling, adding 700-740 parts by weight of epichlorohydrin, dropwise adding a 25-30% by weight aqueous sodium hydroxide solution, stirring and reacting at 40-45° C. for 2-2.5 hours, filtering, washing with water and ethanol, and drying to obtain the epoxidized cellulose.

7. Use of the flotation depressant for talc purification according to any one of claims 1 to 6 in flotation separation of molybdenite and talc.

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