Low-grade aphanitic graphite flotation reagent, preparation method thereof and mineral processing process

Abstract

The application discloses a low-grade aphanitic graphite flotation reagent and a preparation method and a beneficiation process thereof, and belongs to the field of graphite beneficiation process, and comprises the following steps: mixing wood ash and deionized water and then heating; obtaining potassium carbonate alkali liquor through magnetic stirring, standing and depositing and double-layer filter paper suction filtration in sequence; taking the potassium carbonate alkali liquor and a sodium hydroxide solution as raw materials to generate fatty acid sodium through saponification reaction; adding sodium chloride into the saponification reaction liquid, stirring, standing and layering, filtering and then taking upper viscous paste, adding n-butanol after heating, stirring, uniformly mixing, cooling to room temperature and obtaining light yellow waxy solid. Through the green, low-cost and high-efficiency flotation reagent design and preparation method, combined with the optimized beneficiation process, the application realizes efficient, energy-saving and high-quality recovery of the low-grade aphanitic graphite, and has the advantages of significant technical advancement, economy and environmental protection.

Description

Technical Field

[0001] This invention belongs to the field of graphite beneficiation technology, specifically relating to a low-grade cryptocrystalline graphite flotation reagent, its preparation method, and beneficiation process. Background Technology

[0002] Cryptocrystalline graphite has strong surface adsorption, resulting in lower natural floatability than flake-shaped crystalline graphite. Conventional graphite flotation processes commonly use hydrocarbon oils such as kerosene and diesel oil as collectors, and frothers such as pine oil, cresol acid, camphor oil, and ether alcohols as frothers.

[0003] Cryptocrystalline graphite has a fine particle size, and the ultrafine particles result in a large total surface area. This requires a large amount of kerosene to effectively cover the mineral particles. Furthermore, the high surface energy of these fine particles makes them prone to adsorbing water molecules or hydrophilic impurities, reducing their hydrophobicity. Using conventional flotation reagents may not yield a qualified concentrate product, or even make it virtually impossible to recover graphite concentrate. Summary of the Invention

[0004] The purpose of this invention is to provide a low-grade cryptocrystalline graphite flotation reagent, its preparation method, and mineral processing technology to solve the technical problem that existing conventional flotation reagents cannot obtain qualified concentrate products or even recover graphite concentrate.

[0005] The technical solution adopted by this invention to solve the technical problem is as follows:

[0006] In a first aspect, the present invention provides a method for preparing a low-grade cryptocrystalline graphite flotation reagent.

[0007] The present invention provides a method for preparing a low-grade cryptocrystalline graphite flotation reagent, comprising the following steps:

[0008] (1) Mix wood ash and deionized water and heat to 70℃-90℃; then pass through magnetic stirring, static precipitation, and double-layer filter paper to obtain potassium carbonate alkaline solution.

[0009] (2) Using potassium carbonate alkaline solution and sodium hydroxide solution as raw materials, a saponification reaction is carried out to produce sodium fatty acid;

[0010] (3) Add sodium chloride to the saponification reaction solution, stir, let stand and separate into layers, filter and take the upper viscous paste, heat to 60℃-75℃, add n-butanol, stir and mix evenly, cool to room temperature to obtain a light yellow waxy solid.

[0011] In a preferred embodiment, in step (1), the solid-liquid ratio of the plant ash and deionized water is 1:5-1:10, with units of g:ml.

[0012] In a preferred embodiment, in step (1), the concentration of the potassium carbonate alkaline solution is 10%-15%.

[0013] In a preferred embodiment, the saponification reaction process in step (2) is as follows:

[0014] Heat the potassium carbonate alkaline solution to 80℃-95℃, slowly add oleic acid, and stir at a constant temperature. The reaction solution changes from turbid to milky white and viscous. When the pH value is less than 8, add sodium hydroxide solution dropwise until the pH is 9~10 to neutralize the remaining oleic acid. Take the reaction solution into cold water. No oil drops will precipitate. At this point, the saponification reaction is complete, and sodium fatty acid is produced.

[0015] In a preferred embodiment, the volume ratio of potassium carbonate alkaline solution to oleic acid is 25:4-20:7.

[0016] In a preferred embodiment, the concentration of the sodium hydroxide solution is 15%-30%.

[0017] In a preferred embodiment, in step (3), the mass ratio of sodium chloride to sodium fatty acid is 0.2:1-0.4:1.

[0018] In a preferred embodiment, in step (3), the solid-liquid ratio of the upper viscous paste to n-butanol is 1:2-1:5, in g:ml.

[0019] Secondly, the present invention provides a low-grade cryptocrystalline graphite flotation reagent obtained by the above preparation method.

[0020] Thirdly, the present invention provides a mineral processing technology using the aforementioned low-grade cryptocrystalline graphite flotation reagent.

[0021] The beneficial effects of this invention are:

[0022] 1. The agent has superior performance, combining both harvesting and foaming functions;

[0023] The flotation reagent prepared in this invention has the dual function of a collector and a frother, replacing the traditional "kerosene + pine oil" combination and simplifying the reagent preparation process. The hydrophobic chain (C17) of sodium fatty acid forms π-stacking adsorption with the edge of graphite; the carboxylate group coordinates with metal ions on the mineral surface to form a dense adsorption film, significantly improving the hydrophobicity of graphite; the critical wetting contact angle increases from 78° to 85°, the absolute value of the Zeta potential decreases, and bubble-particle adhesion is promoted.

[0024] 2. Low raw material cost, green and environmentally friendly;

[0025] This invention extracts potassium carbonate from wood ash, a widely available and inexpensive raw material, thus realizing the resource utilization of agricultural waste. This invention contains no toxic or harmful substances; the main components are natural extracts and conventional chemical raw materials, making it environmentally friendly and easy to industrialize.

[0026] 3. The flotation effect is significantly improved;

[0027] The present invention achieves both high concentrate grade and high recovery rate: the concentrate grade reaches 78.82% and the recovery rate reaches 83.52%; compared with conventional reagents (Comparative Example 1: grade 49.87%, recovery rate 17.20%), the flotation effect is significantly improved.

[0028] This invention is applicable to low-grade cryptocrystalline graphite, and has excellent flotation adaptability, especially for cryptocrystalline graphite with fine embedded particle size and high surface energy.

[0029] 4. Simplified process flow and reduced energy consumption;

[0030] This invention reduces the required grinding fineness, decreasing the regrinding fineness of the rough concentrate from 93% to 67.44% (-0.045mm), significantly reducing ball mill energy consumption. The invention also reduces the number of refining processes from the traditional seven to four, shortening the process and reducing equipment investment and floor space requirements.

[0031] 5. Strong synergistic effect of drug components;

[0032] This invention adjusts the pH of the slurry using potassium carbonate and complexes Ca... 2+ / Mg 2+ It inhibits quartz activation and enhances the interaction between graphite and reagents; it promotes the hemimicelle adsorption of sodium fatty acids on the graphite surface by compressing the electric double layer with sodium chloride; n-butanol acts as a micelle stabilizer to reduce the critical micelle concentration, improve the foam structure, and enhance foam stability; and it maintains an alkaline environment with sodium hydroxide to promote the ionization of sodium fatty acids and enhance adsorption capacity.

[0033] 6. Significant economic benefits;

[0034] This invention can replace part of the kerosene, reducing the amount of reagents used; the concentrate grade of this invention meets the raw material standards for casting carbon raisers, improving the concentrate quality and making it suitable for the production of mid-range refractory materials; the overall cost of this invention is reduced, with low reagent cost, low energy consumption, and a short process, resulting in a significant decrease in overall flotation cost.

[0035] This invention achieves efficient, energy-saving, and high-quality recovery of low-grade cryptocrystalline graphite through a green, low-cost, and efficient flotation reagent design and preparation method combined with an optimized mineral processing technology. It has significant technological advantages, economic benefits, and environmental friendliness. Detailed Implementation

[0036] In a first aspect, the present invention provides a method for preparing a low-grade cryptocrystalline graphite flotation reagent.

[0037] The present invention provides a method for preparing a low-grade cryptocrystalline graphite flotation reagent, comprising the following steps:

[0038] (1) Mix wood ash and deionized water at a solid-liquid ratio of 1:5-1:10 (unit: g:ml) and heat to 70℃-90℃; after magnetic stirring, static sedimentation, and double-layer filter paper filtration, a potassium carbonate alkaline solution with a concentration of 10%-15% is obtained.

[0039] (2) Using potassium carbonate alkaline solution and sodium hydroxide solution as raw materials, a saponification reaction is carried out to produce sodium fatty acid;

[0040] Heat the potassium carbonate solution to 80℃-95℃, and slowly add oleic acid. The volume ratio of potassium carbonate solution to oleic acid is 25:4-20:7. Stir at a constant temperature. The reaction solution changes from turbid to milky white and viscous. When the pH value is less than 8, add 15%-30% sodium hydroxide solution dropwise until the pH is 9-10 to neutralize the remaining oleic acid. Put the reaction solution into cold water. If no oil drops are precipitated, the saponification reaction is complete, and sodium fatty acid is produced.

[0041] (3) Sodium chloride is added to the saponification reaction solution at a mass ratio of sodium chloride to sodium fatty acid of 0.2:1-0.4:1. The mixture is stirred, allowed to stand and separate into layers, filtered, and the upper viscous paste is taken. The mixture is heated to 60℃-75℃, and n-butanol is added at a solid-liquid ratio of 1:2-1:5 (in g:ml). The mixture is stirred, mixed evenly, and cooled to room temperature to obtain a pale yellow waxy solid.

[0042] Secondly, the present invention provides a low-grade cryptocrystalline graphite flotation reagent obtained by the above preparation method.

[0043] Thirdly, the present invention provides a mineral processing technology using the aforementioned low-grade cryptocrystalline graphite flotation reagent.

[0044] Considering the characteristics of cryptocrystalline graphite, its surface has strong adsorption properties, easily adsorbing water molecules or impurities, resulting in poor hydrophobicity. Conventional flotation reagents such as kerosene require large quantities to cover the surface. This invention utilizes wood ash to extract potassium carbonate, then saponifies oleic acid to produce sodium fatty acid, followed by the addition of sodium chloride and n-butanol to obtain a pale yellow waxy solid, which is the low-grade cryptocrystalline graphite flotation reagent. In addition to sodium fatty acid, the prepared flotation reagent also contains some unreacted potassium carbonate, sodium chloride, n-butanol, sodium hydroxide, etc.

[0045] Sodium fatty acids act as a collector and also have a foaming effect. Sodium fatty acids contain carboxyl groups (COO₂). - The carboxylate group (C17) forms a π-pack with the graphite edge defect site through the hydrophobic chain (C17) and long-chain alkyl group (C17), with an adsorption energy of -42kJ / mol. The carboxylate group coordinates with the metal ions on the mineral surface to form a dense directional adsorption film, which reduces the hydrophilicity of the mineral surface and enhances the stability of hydrophobic-bubble adhesion, thus improving the grade of concentrate and enhancing the recovery effect.

[0046] The potassium carbonate in wood ash helps regulate pH. Residual potassium carbonate provides CO3. 2- Can complex Ca 2+ / Mg 2 + It reduces gangue activation and has better dispersibility than Cl. - / OH - Potassium carbonate helps disperse cryptocrystalline graphite in the slurry. It can inhibit the dissociation of Si-OH on the surface of quartz (SiO2), increase the negative charge density of carboxylate ions, enhance the van der Waals interaction with graphite, thereby reducing the hydrophilicity of gangue. At the same time, it increases the interaction between graphite and flotation reagents, which is beneficial to the separation of concentrate and gangue minerals and reduces the impurity content in the concentrate.

[0047] Sodium chloride can help precipitate or stabilize colloids. As an electrolyte, sodium chloride can reduce the solubility of saponified molecular micelles. The residual sodium chloride concentration in the pulp is low; this low concentration of electrolyte can lower the energy barrier between graphite and bubbles, promoting bubble-particle adhesion. Sodium chloride provides Na... + Compressing the double layer enhances the hemimicelle adsorption of sodium fatty acids on the graphite surface, improves hydrophobicity, increases the critical wetting contact angle from 78° to 85°, and reduces the Zeta potential on the graphite surface from -28mV to -18mV. The decrease in the absolute value of the Zeta potential directly leads to a reduction in the repulsive force of the double layer, which reduces electrostatic repulsion between particles and promotes the adsorption of agents on the graphite surface.

[0048] As a mixed micelle stabilizer, n-ethanol can reduce the critical micelle concentration (CMC) from 0.8 to 0.45 mmol / L, improve the foam microstructure (surface viscosity from 0.032 to 0.058 Pa·s), and form a mixed micelle network, resulting in a more uniform foam pore size distribution. The mixed micelles suppress bubble coalescence through steric hindrance, enhancing foam stability, extending foam lifespan, and increasing the interaction time between the foam and graphite mineral particles. Meanwhile, n-butanol is a good organic solvent; upon heating, it can dissolve some soap bases, significantly reducing the viscosity of the system, making it easier to stir and mix evenly, and improving its fluidity.

[0049] Sodium hydroxide helps maintain an alkaline environment in the slurry and promotes the ionization of sodium fatty acids into the more reactive RCOO. - Ions enhance adsorption on the graphite surface, thereby improving the flotation effect of cryptocrystalline graphite.

[0050] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0051] Example 1: Preparation of a low-grade cryptocrystalline graphite flotation reagent

[0052] (1) Add 100g of wood ash and 300ml of deionized water to a beaker and heat to 70℃. Stir magnetically for 30min, let stand and precipitate for 10min, and finally filter with double-layer filter paper to obtain about 250ml of potassium carbonate alkaline solution with a concentration of about 10%.

[0053] (2) Using potassium carbonate alkaline solution and sodium hydroxide solution as raw materials, a saponification reaction is carried out to produce sodium fatty acids:

[0054] Heat the potassium carbonate alkaline solution to 85℃, and slowly add 40ml of oleic acid; stir at a constant temperature for 1 hour. The reaction solution changes from turbid to milky white and viscous. When the pH value is less than 8, add 30% sodium hydroxide solution dropwise until the pH is 9~10 to neutralize the remaining oleic acid; take 1 drop of the reaction solution and put it into cold water. No oil droplets are precipitated. At this time, the saponification reaction is completed and sodium fatty acid is generated.

[0055] (3) Add 10g of sodium chloride to the saponification reaction solution (containing 0.3g of sodium fatty acid), stir for 10min, let stand and separate into layers, filter and take 1g of the upper viscous paste, heat to 60℃, add 5ml of n-butanol, stir and mix evenly, cool to room temperature to obtain a light yellow waxy solid.

[0056] Example 2: Flotation test was conducted using the flotation reagents prepared in Example 1.

[0057] Using cryptocrystalline graphite ore from Inner Mongolia as the experimental target, 10 g / t of conventional collector kerosene was used, and 80 g / t of flotation reagent (Example 1) was prepared. The coarse grinding fineness was 85% -0.075 mm. After one roughing stage, the rough concentrate was regrinded, with a regrinding fineness of 67.44% -0.045 mm. Four cleaning stages and one scavenging stage were performed to obtain graphite concentrate product: C. 固 Grade: 78.82%, Recovery rate: 83.52%.

[0058] Example 3: Preparation of a low-grade cryptocrystalline graphite flotation reagent

[0059] The procedure was carried out according to Example 1, except that the concentration of sodium hydroxide solution and the amount of n-butanol were different. In this Example 3, the concentration of sodium hydroxide solution was 20% and the amount of n-butanol was 4 ml.

[0060] Example 4: Flotation test was conducted using the flotation reagents prepared in Example 3.

[0061] Using the same cryptocrystalline graphite ore from Inner Mongolia as in Example 2, 10 g / t of conventional collector kerosene was used, and 80 g / t of flotation reagent (Example 3) was prepared. The coarse grinding fineness was 85% -0.075 mm. After one roughing stage, the rough concentrate was regrinded, with a regrinding fineness of 67.44% -0.045 mm. Four cleaning stages and one scavenging stage were performed to obtain the graphite concentrate product: C. 固 Grade 74.31%, recovery rate 79.92%.

[0062] A comparison of Example 4 and Example 2 shows that the concentrate grade and recovery rate are significantly reduced. This indicates that reducing the amount of sodium hydroxide and n-butanol used in the formulation process affects the ore flotation effect.

[0063] Comparative Example 1 uses conventional flotation reagents for flotation tests.

[0064] The same cryptocrystalline graphite ore from Inner Mongolia as in Example 2 was used as the test target, with raw ore C... 固 With a grade of 47.73%, using conventional collectors (kerosene 180g / t) and frother (oil No. 2 100g / t), and coarse grinding to a fineness of -0.075mm (85%), after one roughing stage, the rough concentrate is regrinded to a fineness of -0.045mm (67.44%). After four cleaning stages and one scavenging stage, the graphite concentrate product C is obtained. 固 Grade 49.87%, recovery rate 17.20%.

[0065] As shown in Comparative Example 1, when conventional collectors and frothers are used, and the coarse grinding fineness is -0.075mm accounting for 85%, after one roughing, the rough concentrate is regrinded. When the regrinding fineness is -0.045mm accounting for 67.44%, the grade of graphite concentrate is almost no higher than that of the original ore, and the recovery rate is extremely low.

[0066] Comparative Example 2 used conventional flotation reagents for flotation tests.

[0067] Using the same cryptocrystalline graphite ore from Inner Mongolia as in Example 2, 180 g / t of conventional collector kerosene and 100 g / t of frother No. 2 oil were employed. The coarse grinding fineness was -0.075 mm, accounting for 85%. After one roughing stage, the rough concentrate was regrinded, with a regrinding fineness of -0.045 mm accounting for 93%. After 7 cleaning stages and 1 scavenging stage, the graphite concentrate product C was obtained. 固 Grade: 69.42%, Recovery rate: 50.37%.

[0068] As shown in Comparative Example 2, using the same flotation reagents and coarse grinding fineness as Comparative Example 1, while increasing the regrinding fineness of the rough concentrate (from -0.045 mm to 93%) and increasing the number of cleaning cycles to 7, the graphite concentrate product C can be obtained. 固 Grade: 69.42%, Recovery rate: 50.37%.

[0069] The above experiments demonstrate that the present invention has the following technical advantages:

[0070] (1) Using the flotation reagent prepared in this invention can reduce the amount of collector kerosene by about 170g / t.

[0071] (2) Using the flotation reagents prepared in this invention, the proportion of -0.045mm in the regrinding fineness of the rough concentrate decreased from 93% to 67.44%, reducing the energy consumption of the ball mill. Among them, compared with Example 2, Comparative Example 2 showed a significant increase in grinding energy consumption. The energy consumption increase per ton of rough concentrate from 67.44% -0.045mm to 93% was approximately 30.2 kWh / t. Based on the industrial electricity price of RMB 0.42 / kWh in Inner Mongolia, the grinding cost per ton of ore increased by approximately RMB 12.7 / ton (30.2 × 0.42 ≈ 12.7). The grade of graphite concentrate increased from 69.42% to 78.82%, meeting the raw material standard for casting carbon raisers, and can be used in the production of mid-range refractory materials. The recovery rate increased from 50.37% to 83.52%, and the amount of recovered concentrate increased by 33%.

[0072] (3) Using the flotation reagents prepared in this invention improves flotation efficiency and shortens the process flow. The number of cleaning processes is reduced from 7 to 4, eliminating three cleaning processes, reducing equipment footprint, and resulting in a shorter process and higher flotation efficiency.

[0073] This invention discloses a low-grade cryptocrystalline graphite flotation reagent, its preparation method, and beneficiation process. Those skilled in the art can refer to the content of this document and appropriately modify the process parameters to achieve the desired result. It is particularly important to note that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in this invention. The product of this invention has been described through preferred embodiments, and those skilled in the art can clearly modify or appropriately change and combine the product described herein without departing from the content, spirit, and scope of this invention to realize and apply the technology of this invention.

Claims

1. A method for preparing a low-grade cryptocrystalline graphite flotation reagent, characterized in that, Includes the following steps: (1) Mix wood ash and deionized water and heat to 70℃-90℃; then, after magnetic stirring, settling and filtration through double-layer filter paper, obtain potassium carbonate alkaline solution; the concentration of the potassium carbonate alkaline solution is 10%-15%; (2) Using potassium carbonate alkaline solution and sodium hydroxide solution as raw materials, a saponification reaction is carried out to generate sodium fatty acid; the saponification reaction process is as follows: the potassium carbonate alkaline solution is heated to 85℃-95℃, oleic acid is slowly added, and the mixture is stirred at a constant temperature. The reaction solution changes from turbid to milky white and viscous. When the pH value is less than 8, sodium hydroxide solution is added dropwise until the pH is 9~10 to neutralize the remaining oleic acid; the reaction solution is taken into cold water, and no oil drops are precipitated. At this time, the saponification reaction is completed and sodium fatty acid is generated; the volume ratio of potassium carbonate alkaline solution to oleic acid is 25:4-20:

7. (3) Add sodium chloride to the saponification reaction solution, stir, let stand and separate into layers, filter and take the upper viscous paste, heat to 60℃-75℃, add n-butanol, stir and mix evenly, cool to room temperature to obtain a light yellow waxy solid.

2. The method for preparing a low-grade cryptocrystalline graphite flotation reagent according to claim 1, characterized in that, In step (1), the solid-liquid ratio of the plant ash and deionized water is 1:5-1:10, with units of g:ml.

3. The method for preparing a low-grade cryptocrystalline graphite flotation reagent according to claim 1, characterized in that, The concentration of the sodium hydroxide solution is 15%-30%.

4. The method for preparing a low-grade cryptocrystalline graphite flotation reagent according to claim 1, characterized in that, In step (3), the mass ratio of sodium chloride to sodium fatty acid is 0.2:1-0.4:

1.

5. The method for preparing a low-grade cryptocrystalline graphite flotation reagent according to claim 1, characterized in that, In step (3), the solid-liquid ratio of the upper viscous paste to n-butanol is 1:2-1:5, in g:ml.

6. A low-grade cryptocrystalline graphite flotation reagent obtained by the preparation method according to any one of claims 1-5.

7. A mineral processing technology using a low-grade cryptocrystalline graphite flotation reagent as described in claim 6.