Synthesis method and use method of fine particle lepidolite flotation activity mud inhibitor

Abstract

This invention relates to the field of mineral flotation technology, and discloses a method for synthesizing and using an active slime suppressant for the flotation of fine-grained lepidolite. The synthesis method includes: S1. Mixing polyacrylamide (molecular weight 50,000-100,000), phosphate-modified chitosan, and sodium hydroxide at a mass ratio of 1:3:1 to 1:5:1, hydrolyzing at 90°C for 3-5 hours, and neutralizing with oxalic acid solution to pH 5-6 to obtain the hydrolysis product; S2. Dispersing the hydrolysis product using ultrasonic stirring, and then activating it with high-shear stirring using a high-pressure homogenizer to obtain the active slime suppressant. During flotation, 100-200 g / t of this slime suppressant is added to the fine-grained lepidolite slurry. After slurry conditioning, inhibitors and collectors are added sequentially, and the slurry is subjected to a roughing, cleaning, and scavenging process to obtain lepidolite concentrate. This invention, through the synergistic modification of alkaline hot hydrolysis and physical activation, enables the slime suppressant to possess the dual functions of inhibiting slime agglomeration and selectively suppressing biotite, significantly reducing collector consumption and improving concentrate grade and recovery rate.

Description

Technical Field

[0001] This invention relates to the field of mineral flotation technology, and in particular to a method for synthesizing and using a fine-particle lithium mica flotation active mud suppressant. Background Technology

[0002] With the continuous development of the battery and energy storage industry, the demand and price of lithium carbonate and lithium iron phosphate, which are required as cathode materials, are constantly rising, leading to a year-on-year increase in the demand for lithium mineral resources. As high-quality lithium mineral resources are gradually developed, research and development of technologies for the development and utilization of fine-grained, complex, and difficult-to-process lepidolite mineral resources is of great significance.

[0003] Because mica minerals are prone to becoming muddy under natural conditions and during grinding, and often coexist with minerals such as biotite, the amount of flotation collectors required increases. Furthermore, since lepidolite and biotite have similar flotation properties, biotite minerals easily enter the lithium concentrate, resulting in a decrease in product grade. Therefore, existing technologies typically employ a "desliming-flotation" process for lepidolite flotation recovery. However, during this process, a large amount of lepidolite minerals is lost to the tailings. Statistics show that in recent years, in the development of lepidolite mines in Jiangxi Province, the amount of lithium resources lost in desliming tailings alone accounts for approximately 5%-8% of the total local lithium resources. This not only causes a serious waste of lithium resources but also leads to tailings accumulation and environmental problems.

[0004] Therefore, developing a flotation reagent that can effectively suppress slime and selectively suppress impurity minerals such as biotite is of great practical significance for achieving efficient flotation recovery of fine-grained lepidolite, reducing reagent consumption, and improving concentrate grade and recovery rate. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of poor flotation effect, large reagent dosage and low separation efficiency of existing fine-particle lepidolite, and to provide a method for synthesizing an active mud suppressant for flotation of fine-particle lepidolite and a flotation method using the mud suppressant, so as to achieve efficient recovery of fine-particle lepidolite.

[0006] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a method for synthesizing a fine-particle lithium mica flotation active mud suppressant, the core of which lies in the two-step modification treatment of polyacrylamide and phosphate chitosan of a specific molecular weight by alkaline hot water hydrolysis and physical activation.

[0007] Specifically, the synthesis method of the present invention includes the following steps: S1. Polyacrylamide with a molecular weight of 50,000 to 100,000, phosphate chitosan and sodium hydroxide are mixed in a mass ratio of 1:3:1 to 1:5:1 and hydrolyzed at 90°C for 3 to 5 hours. After hydrolysis, the mixture is neutralized with a 5% oxalic acid solution and the pH is adjusted to 5 to 6 to obtain the partial hydrolysis products of polyacrylamide and phosphate chitosan. S2. The hydrolysis product is first ultrasonically stirred and dispersed for 1-2 hours at an ultrasonic frequency of 30-60 kHz and an ultrasonic power of 2-5 kW. Then, it is activated by high-shear stirring in a high-pressure homogenizer at a speed of 1000-3000 r / min for 1-3 hours. During the homogenization process, the material temperature is controlled at 50-70 ℃ and the homogenization pressure is 150-200 MPa to obtain the fine-particle lithium mica flotation active mud suppressant.

[0008] As a preferred technical solution, in step S1, the molecular weight of polyacrylamide is 50,000, the mass ratio of polyacrylamide, phosphate chitosan and sodium hydroxide is 1:3:1, and the hydrolysis reaction time is 3 hours.

[0009] As a preferred technical solution, in step S1, the molecular weight of polyacrylamide is 100,000, the mass ratio of polyacrylamide, phosphate chitosan and sodium hydroxide is 1:5:1, and the hydrolysis reaction time is 5 hours.

[0010] As a preferred technical solution, in step S2, the ultrasonic stirring and dispersion frequency is 60 kHz. Ultrasonic waves in this frequency range can effectively generate cavitation, which helps to break the hydrogen bonds and long molecular chains between chitosan molecules, promoting the formation of multi-branched structures.

[0011] As a preferred technical solution, in step S2, the material temperature is controlled at 70°C by the circulating cooling jacket of the high-pressure homogenizer; temperature control by the circulating cooling jacket can prevent overheating and excessive degradation of the polymer chains. The homogenization pressure is 200 MPa.

[0012] The present invention also provides a fine-particle lithium mica flotation active mud suppressant prepared according to the above synthesis method.

[0013] The present invention also provides a method for flotation of fine-particle lepidolite using the above-mentioned active mud suppressant, comprising the following steps: (1) Add 100-200 g / t of the active mud suppressant described in claim 6 to a fine-grained lithium mica ore slurry with a Li2O grade of 0.3%-0.8% and a particle size of -0.074 mm accounting for 60%-80%, stir for 3-5 minutes, and adjust the slurry.

[0014] (2) Add inhibitors and collectors to the slurry after slurry conditioning, and carry out flotation using a flotation process of one roughing, three cleaning and two scavenging to obtain lithium mica concentrate and tailings.

[0015] As a preferred technical solution, the Li2O grade of the fine-grained lithium mica ore is 0.3%, the particle size of -0.074mm accounts for 60%, the amount of active mud suppressant added is 100 g / t, the stirring time is 3 minutes, and the amount of collector used is 250 g / t.

[0016] As a preferred technical solution, the Li2O grade of the fine-grained lithium mica ore is 0.8%, the particle size of -0.074mm accounts for 80%, the amount of active mud suppressant added is 200 g / t, the stirring time is 5 minutes, and the amount of collector used is 350 g / t.

[0017] As a preferred technical solution, the amount of inhibitor added is 80-150 g / t.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. Molecular weight selectivity This invention precisely selects polyacrylamide with a molecular weight of 50,000 to 100,000. This specific molecular weight range can effectively agglomerate the fine mudstone minerals in the lepidolite ore, while avoiding the non-selective inclusion of lepidolite minerals into the tailings due to excessively large molecular weights, thus achieving precise and efficient agglomeration of the ore slime.

[0019] 2. Functional properties of chemical activation High-temperature hydrolysis of polyacrylamide and phosphate-modified chitosan under sodium hydroxide conditions yields highly active carboxyl and hydroxyl groups. These groups can form hydrogen bonds and undergo chemisorption with iron ions on the surface of biotite minerals. Simultaneously, the phosphate groups in the phosphate-modified chitosan can also interact with biotite through chemisorption. The synergistic effect of these multiple functional groups achieves highly efficient and selective suppression of biotite, a byproduct of lepidolite minerals.

[0020] 3. Slime agglomeration and reagent consumption reduction Both polyacrylamide and phosphate-modified chitosan have long molecular chains, enabling them to effectively agglomerate fine mineral slime below -5μm, significantly improving the settling performance of the slime. This selective agglomeration effectively prevents the slime from entering the lepidolite concentrate through water entrainment and foam inclusions, thereby greatly reducing the ineffective consumption of flotation collectors and improving the concentrate grade.

[0021] 4. The key role of physical activation Conventional chitosan molecules tend to cross-link and aggregate due to strong hydrogen bonds, leading to a decline in performance. This invention, through two physical processes—ultrasonic dispersion and high-pressure homogenization with high-shear stirring—effectively breaks down the cross-linked chitosan molecular chains, dispersing them into smaller, multi-branched chains. This reduces the non-selective entrainment of lepidolite by the large molecular chains and also reduces the steric hindrance effect of chitosan molecules, significantly enhancing the interaction strength between its active groups and the iron-containing active sites on the biotite surface, thus significantly improving the selective inhibition effect of the agent on biotite.

[0022] In summary, this invention modifies polyacrylamide and phosphate chitosan to a specific molecular weight through a synergistic process of alkaline hydrolysis and physical activation, achieving multiple functions with a single agent: it both agglomerates ore slime and selectively inhibits biotite, thereby achieving excellent results in the flotation of fine-particle lepidolite, while simultaneously reducing reagent consumption and improving concentrate grade and recovery rate. Attached Figure Description

[0023] Figure 1 This is a flowchart illustrating the overall process of the synthesis method of the present invention. Figure 2 This is a process flow diagram of the active sludge inhibitor used in this invention. Detailed Implementation

[0024] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below with reference to specific embodiments.

[0025] Example 1 Synthesis of mud inhibitors: S1. Polyacrylamide with a molecular weight of 50,000 was selected and mixed with phosphate chitosan and sodium hydroxide at a mass ratio of 1:3:1. The mixture was placed in a water bath and hydrolyzed at 90°C for 3 hours. After the reaction was completed, a 5% oxalic acid solution was added for neutralization, and the pH of the system was adjusted to 5-6 to obtain the partially hydrolyzed product of polyacrylamide and phosphate chitosan.

[0026] S2. The above hydrolysis product is stirred and dispersed using ultrasound at a frequency of 30 kHz for 1 hour. Then, it is placed in a high-pressure homogenizer and activated by high-shear stirring at a speed of 1000 r / min for 1 hour. During the homogenization process, the material temperature is controlled at 50 ℃ and the homogenization pressure is 150 MPa, thus obtaining the fine-particle lithium mica flotation active mud suppressant of this embodiment.

[0027] Application of fine-particle lithium mica flotation active slime inhibitor in flotation:

[0028] Take fine-grained lithium mica ore from Yichun, Jiangxi Province, with a Li2O grade of 0.3% and a particle size of -0.074mm accounting for 60%. Add 100 g / t of the mud suppressant prepared in this example to the ore slurry and stir to adjust the slurry for 3 minutes.

[0029] A flotation process consisting of one roughing, three cleaning, and two scavenging stages was adopted. The final lithium mica concentrate had a Li₂O grade of 2.12% and a Li₂O recovery rate of 78.52%.

[0030] Comparative Example 1 The same lepidolite ore as in Example 1 was used, and flotation was performed directly without adding any slime inhibitor. 150 g / t of depressant and 500 g / t of collector were added sequentially, using the same "one rougher, three cleaners, two scavengers" flotation process. The final concentrate Li2O grade was only 1.65%, and the Li2O recovery rate was only 66.25%.

[0031] Comparative Example 2 Take the same lithium mica ore as in Example 1, and add 100 g / t of a reagent consisting of a simple mixture of 50,000 molecular weight polyacrylamide and phosphate chitosan at a mass ratio of 1:3 (without hydrolysis and physical activation treatment as in Example 1). After stirring for 3 minutes, add 100 g / t of inhibitor and 350 g / t of collector sequentially, and use the same flotation process. The final concentrate Li2O grade is 2.02%, and the Li2O recovery rate is 70.52%.

[0032] Comparative Example 3 Take the same lithium mica ore as in Example 1, add 100 g / t of reagent that has only undergone hydrolysis in step S1 of Example 1 but not ultrasonic dispersion and high-shear stirring activation in step S2. After stirring for 3 minutes, add 100 g / t of inhibitor and 350 g / t of collector sequentially, and use the same flotation process. The final concentrate Li2O grade is 2.02%, and the Li2O recovery rate is 73.52%.

[0033] Comparative analysis of results: Comparing Example 1 with Comparative Example 1, it can be seen that even if the amount of collector is doubled, the sorting index is still very poor when no mud suppressant is added, and the efficient recovery of fine-particle lepidolite cannot be achieved, which confirms the necessity of mud suppressant.

[0034] Comparing Example 1 with Comparative Example 2, it can be seen that the simple mixture without hydrolysis and physical activation treatment has a small number of active functional groups, and the molecules cross-link and aggregate due to hydrogen bonding, which cannot efficiently achieve selective aggregation of sludge, resulting in poor sorting index. This proves the indispensability of the synergistic process of alkaline hot water hydrolysis and physical activation in this invention.

[0035] Comparing Example 1 with Comparative Example 3, it can be seen that without the high-shear stirring activation step, the chitosan agent molecules cannot form a highly active small molecule branched structure, which cannot effectively inhibit biotite. Furthermore, due to the long molecular chain, non-selective entrainment of lepidolite occurs, thereby reducing the sorting index. This strongly demonstrates the key role of the physical activation step in this invention.

[0036] Example 2 Synthesis of mud inhibitors: S1. Polyacrylamide with a molecular weight of 100,000 was selected and mixed with phosphate chitosan and sodium hydroxide at a mass ratio of 1:5:1. The mixture was placed in a water bath and hydrolyzed at 90°C for 5 hours. After the reaction was complete, the solution was neutralized to pH 6 with 5% oxalic acid to obtain a partial hydrolysis product.

[0037] S2. The above hydrolysis products are stirred and dispersed using ultrasound at a frequency of 60 kHz for 2 hours; then placed in a high-pressure homogenizer and activated by high-shear stirring at a speed of 3000 r / min for 2 hours. During the homogenization process, the material temperature is controlled at 70 ℃ and the homogenization pressure is 200 MPa, thus obtaining the active mud inhibitor of this embodiment.

[0038] Application of fine-particle lithium mica flotation active slime inhibitor in flotation: Take fine-grained lithium mica ore from Chifeng area of ​​Inner Mongolia with a Li2O grade of 0.8% and a particle size of -0.074mm accounting for 80%, add 200 g / t of the mud suppressant prepared in this example to the slurry, and stir to adjust the slurry for 5 minutes.

[0039] 100 g / t of inhibitor and 350 g / t of collector were added sequentially to the slurry after conditioning, and a flotation process of one roughing, three cleaning, and two scavenging steps was adopted. The final lithium mica concentrate was obtained with a Li2O grade of 2.52% and a Li2O recovery rate of 85.86%.

[0040] Comparative Example 4 Using the same raw ore as in Example 2, without adding any mud suppressant, 150 g / t of inhibitor and 800 g / t of collector were added sequentially for flotation. The concentrate Li2O grade was 2.25%, and the recovery rate was 76.25%.

[0041] Comparative Example 5 The same raw ore as in Example 2 was used, but 200 g / t of a reagent consisting of a simple mixture of 100,000 molecular weight polyacrylamide and phosphate chitosan at a mass ratio of 1:5 was added. After stirring for 3 minutes, 100 g / t of inhibitor and 350 g / t of collector were added sequentially for flotation. The concentrate Li2O grade was 2.32%, and the recovery rate was 80.52%.

[0042] Comparative Example 6 Take the same raw ore as in Example 2, add 200 g / t of reagent that has only undergone hydrolysis in step S1 of Example 2 but not physical activation in step S2, stir for 3 minutes, and then add 150 g / t of inhibitor and 400 g / t of collector for flotation. The concentrate Li2O grade is 2.36%, and the recovery rate is 80.52%.

[0043] Comparative analysis of results: The comparison between Example 2 and Comparative Examples 4, 5, and 6 reproduced the same patterns and conclusions as in Example 1, further verifying the necessity and synergistic effect of the three technical elements of the present invention—"selection of raw materials with specific molecular weights," "chemical activation by alkaline hot water hydrolysis," and "physical activation by ultrasound and high shear"—in achieving excellent flotation indicators.

[0044] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for synthesizing a fine-particle lithium mica flotation active mud suppressant, characterized in that, Includes the following steps: S1. Polyacrylamide with a molecular weight of 50,000 to 100,000, phosphate chitosan, and sodium hydroxide are mixed in a mass ratio of 1:3:1 to 1:5:1 and hydrolyzed at 90°C for 3 to 5 hours. After hydrolysis, the mixture is neutralized with a 5% oxalic acid solution and the pH is adjusted to 5 to 6 to obtain the hydrolysis product. S2. The hydrolysis product is first ultrasonically stirred and dispersed for 1-2 hours at an ultrasonic frequency of 30-60 kHz and an ultrasonic power of 2-5 kW. Then, it is activated by high-shear stirring in a high-pressure homogenizer at a speed of 1000-3000 r / min for 1-3 hours. During the homogenization process, the material temperature is controlled at 50-70 ℃ and the homogenization pressure is 150-200 MPa to obtain the fine-particle lithium mica flotation active mud suppressant.

2. The synthesis method according to claim 1, characterized in that: In step S1, the molecular weight of polyacrylamide is 50,000, the mass ratio of polyacrylamide, phosphate chitosan and sodium hydroxide is 1:3:1, and the hydrolysis reaction time is 3 hours.

3. The synthesis method according to claim 1, characterized in that: In step S1, the molecular weight of the polyacrylamide is 100,000, the mass ratio of the polyacrylamide, phosphate chitosan, and sodium hydroxide is 1:5:1, and the hydrolysis reaction time is 5 hours.

4. The synthesis method according to claim 1, characterized in that: In step S2, the frequency of ultrasonic stirring and dispersion is 60 kHz.

5. The synthesis method according to claim 1, characterized in that: In step S2, the material temperature is controlled at 70°C by the circulating cooling jacket of the high-pressure homogenizer; the homogenization pressure is 200 MPa.

6. A fine-particle lithium mica flotation active mud suppressant prepared by the synthesis method according to any one of claims 1 to 5.

7. A method for flotation of fine-particle lepidolite using the active mud suppressant of claim 6, characterized in that, Includes the following steps: (1) Add 100-200 g / t of the active mud suppressant described in claim 6 to a fine-grained lithium mica ore slurry with a Li2O grade of 0.3%-0.8% and a particle size of -0.074 mm accounting for 60%-80%, stir for 3-5 minutes, and adjust the slurry. (2) Add inhibitors and collectors to the slurry after slurry conditioning, and carry out flotation using a flotation process of one roughing, three cleaning and two scavenging to obtain lithium mica concentrate and tailings.

8. The flotation method according to claim 7, characterized in that: The fine-grained lithium mica ore has a Li2O grade of 0.3% and a particle size of -0.074mm accounting for 60%. The active mud suppressant is added at a rate of 100 g / t, and the stirring time is 3 minutes. The collector is used at a rate of 250 g / t.

9. The flotation method according to claim 7, characterized in that: The fine-grained lithium mica ore has a Li2O grade of 0.8% and a particle size of -0.074mm accounting for 80%. The active mud suppressant is added at a rate of 200 g / t, and the stirring time is 5 minutes. The collector is used at a rate of 350 g / t.

10. The flotation method according to claim 7, characterized in that: The amount of inhibitor added is 80–150 g / t.

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