A method for recovering fine-grained lepidolite from deslimed product

Abstract

The application discloses a method for recovering fine-grained lepidolite from desliming products, which comprises the following steps: S1, slurry preparation: the desliming products are prepared into a slurry, a combined depressant and a combined collector are sequentially added, and stirring is uniformly performed to obtain a first mixed slurry of lepidolite and reagents; S2, pressure reduction: the first mixed slurry obtained in the step S1 is placed into a pressure reduction device, pressure reduction operation is performed on the first mixed slurry to generate nano bubbles, and a second mixed slurry of lepidolite, reagents and nano bubbles is obtained; S3, lithium flotation: the second mixed slurry is sorted by using a micro-bubble flotation column to obtain a lepidolite concentrate and a tailing. By combining the combined depressant and the anion-cation combined collector, and by adopting the slurry preparation-pressure reduction-lithium flotation process, the high-efficiency recovery of the lepidolite in the desliming products is effectively realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of separation and beneficiation, and particularly relates to a method for recovering micro-fine-grained lepidolite from deslimed products. BACKGROUND

[0002] Lithium is widely used in lithium-ion batteries, nuclear industry and solid fuel and many other fields. As a lithium-containing mineral with large reserves in China, lepidolite is one of the important resources for extracting lithium elements. A large amount of fine-grained minerals are produced in the process of mineralization, weathering and grinding of lithium ore deposits, and the crystal structure and chemical properties of layered aluminosilicate minerals are similar, the grade of valuable metals is generally low, and the embedded particle size is fine, especially the recovery of micro-fine-grained target minerals in overgrinding fine mud products is difficult, which restricts the efficient recovery of lithium resources. In the process of flotation, the probability of collision and adhesion of micro-fine-grained minerals with bubbles is low, and the flotation rate is slow, resulting in low recovery rate and serious loss of valuable metals, which is a severe challenge in the field of mineral processing today. Developing high-selectivity flotation reagents and processes for lithium resources in fine mud products is a difficult problem that needs to be solved in the flotation of micro-fine-grained minerals.

[0003] At present, there is little research on the flotation of micro-fine-grained lepidolite in fine mud products. In terms of reagents, the combination of anion and cation collectors shows strong synergistic effect and high surface activity in the flotation of conventional particle size lepidolite, and has better collecting performance and selectivity than single collector, and is more economical and practical than new collectors, but there is no specific research on micro-fine-grained lepidolite. The research on recovery technology for fine-grained minerals mainly focuses on increasing the apparent particle size of minerals and reducing the size of bubbles, including flocculation flotation, carrier flotation and micro-bubble flotation, etc. However, there is little research on these methods in the field of lepidolite flotation. Micro-nano bubbles produced by reduced pressure are often used to solve the problem of micro-fine-grained flotation. Nano bubbles can selectively adhere to the surface of hydrophobic minerals, enhancing long-range hydrophobic force between mineral particles. Thus, it promotes the hydrophobic flocculation of micro-fine minerals and has great advantages in improving the recovery rate of micro-fine-grained minerals.

[0004] Chinese patent application CN111151381A discloses a preparation method and application of a collector for fine-grained lepidolite flotation, provides a cationic temperature-sensitive collector prepared by copolymerization of N-isopropyl acrylamide and N-[3-dimethylaminopropyl] methacrylamide monomers through free radical polymerization, mainly for flotation of Li2O containing 1.2-1.8% ore with unclear characteristics of lepidolite, 80% of the lithium mica particle size is less than 50μm, and the method is for ore with Li2O content of 0.5-0.6%, and about 50% of the particle size in fine mud is less than 20μm. Chinese patent application CN115155796A discloses a combined flotation-magnetic separation beneficiation method for recovering micro-fine particle lepidolite from tailings, which uses a process of "direct pulp preparation-strong stirring and mixing-pulp column roughing-pulp column cleaning-high gradient magnetic separation scavenging" to separate micro-fine particle lepidolite. Chinese patent application CN115155825A discloses a beneficiation method for recovering micro-fine particle lepidolite from tailings, which develops a short process separation technology of one roughing, two cleaning and one scavenging combined with a pulp column. The methods disclosed in the above two patent applications start from the dispersion principle of ore pulp, use sodium hexametaphosphate to disperse useful minerals and gangue minerals, and use desliming method, which will cause great loss of lithium resources in fine mud. With the continuous rise of lithium metal price, some concentrators try to use flotation column for recovery, but due to the too fine particle size, the effect still needs to be improved. Therefore, it is urgent to develop a reagent and process for recovering micro-fine particle lepidolite in fine mud product to realize efficient recovery of lithium resources. SUMMARY

[0005] In view of the deficiencies of the prior art, the purpose of the present application is to provide a method for recovering micro-fine particle lepidolite from deslimed product, which realizes efficient recovery of micro-fine particle lepidolite in fine mud product.

[0006] To solve the above technical problems, the technical scheme of the present application is as follows:

[0007] A method for recovering micro-fine particle lepidolite from deslimed product, comprising the following steps:

[0008] S1, pulp preparation: the deslimed product is added with water to prepare a certain concentration of ore pulp, and then a combined depressant and a combined collector are added in sequence and stirred uniformly to obtain a first mixture of lepidolite and reagent;

[0009] S2, pressure reduction: the first mixture obtained in step S1 is put into a pressure reduction device to perform pressure reduction operation on the first mixture to generate nano bubbles, and a second mixture of lepidolite, reagent and nano bubbles is obtained;

[0010] S3, lithium flotation: the second mixture is separated by using a micro-bubble flotation column to obtain a lepidolite concentrate and a tailing.

[0011] The lithium mica in the desliming product is fine in size, the combined depressor and the combined collector are added in the pulp conditioning step to stir uniformly to obtain a first mixed ore pulp; in the process of reducing the pressure of the first mixed ore pulp, a large number of micro-nano bubbles are generated in the ore pulp system, and on the basis of the combined depressor and the combined collector, the micro-nano bubbles are more accurately adsorbed on the surface of the fine-grained lithium mica with strong hydrophobicity, so that the fine-grained lithium mica further hydrophobic flocculation occurs, the apparent particle size of the ore particle is increased, and the collision probability with the bubbles in the flotation process is increased, and finally the micro-bubble flotation column is used for flotation, the bubbles generated by the micro-bubble flotation column are smaller than those of the ordinary flotation column and the flotation machine, the collision probability of the target mineral and the bubbles is further increased from the perspective of reducing the bubble size, and the ore pulp is relatively stable and the flocculation structure is not easy to be damaged, which is helpful to finally realize the efficient recovery of the fine-grained lithium mica in the desliming product. The lithium is floated by using the method of weak dispersion and strong flocculation, and the fine-grained lithium mica in the fine mud product is efficiently recovered.

[0012] Further, in step S1, the desliming product is conditioned into a pulp with a mass concentration of 30% to 35%.

[0013] Further, in step S1, the depressor includes at least one of water glass, caustic starch and carboxymethyl cellulose. The combined depressor is configured as an aqueous solution and is directly added for use.

[0014] Preferably, the combined depressor is compounded by water glass, caustic starch and carboxymethyl cellulose in a mass ratio of (1-3):(1-3):(2-6). In this way, the depressor compounded by water glass, caustic starch and carboxymethyl cellulose is added in the pulp conditioning step to adjust the hydrophilicity of the gangue minerals, so that the target minerals and the gangue minerals are dispersed in the pulp to reduce the entrainment. The water glass can enhance the hydrophilicity of the surface of the gangue minerals such as quartz and feldspar, and has a certain dispersion effect; the caustic starch can depress the gangue minerals such as fluorite, quartz and feldspar, and the carboxymethyl cellulose can depress the calcium-containing gangue minerals such as calcite and fluorite, and also has a certain flocculation effect, which is helpful to the formation of flocculation between mineral particles.

[0015] Further, in step S1, the combined collector includes at least one of dodecylamine, sodium oleate, sodium dodecyl sulfate, oxidized paraffin soap and polyaluminum chloride.

[0016] Preferably, the combined collector is compounded by dodecylamine, sodium oleate, sodium dodecyl sulfate, oxidized paraffin soap and polyaluminum chloride in a mass ratio of (4-6):(1-2):(2-5):(2-5):(1-4). In this way, the combined collector compounded by dodecylamine, sodium oleate, sodium dodecyl sulfate, oxidized paraffin soap and polyaluminum chloride is selectively adsorbed on the surface of the fine-grained lithium mica to enhance the hydrophobicity of the fine-grained lithium mica, so that the target minerals are hydrophobic flocculation, and preparation for further efficient collection is made.

[0017] Lepidolite is a typical layered silicate mineral, the basic structure is composed of octahedral cations between two [(Si, Al)O4] tetrahedral network layers, under the action of external force, along the layer fracture, the exposed K + and silicon tetrahedral anions, K + is easily dissolved in aqueous solution H + exchange, the mineral surface has a strong ability to bond, so the surface of lepidolite has a constant negative charge. In solution, dodecylamine mainly exists in the form of cation, sodium oleate, sodium dodecyl sulfate and oxidized paraffin soap exist in the form of anion, cation is first adsorbed on the surface of lepidolite, and then anion is co-adsorbed by electric neutralization to form complex and improve the hydrophobicity of the mineral. Among them, dodecylamine, sodium oleate and oxidized paraffin soap have both collecting ability and foaming performance. Polyaluminum chloride is an inorganic flocculant, which is a water-soluble inorganic polymer between AlCl3 and Al(OH)3. Its structure is composed of multi-carboxyl complex with variable morphology. The flocculation and precipitation speed is fast, and the pH value range is wide. When Al 3+ is dissolved in water, it can strengthen the inhibition of carboxymethyl cellulose on calcite, fluorite and quartz in the slurry. In the synergistic effect of polyaluminum chloride and dodecylamine, sodium oleate and other collectors, the lepidolite particles can be selectively flocculated, the collision probability with gas bubbles can be increased, and the floatability can be improved.

[0018] Further, the combined collector is prepared into an aqueous solution by using hot water with a temperature of 45-55℃, and the mass concentration of the combined collector is 5-10%.

[0019] Further, the decompression device in step S2 is known in the prior art.

[0020] Further, in step S2, the decompression operation condition is 0.01-0.03 MPa, and the decompression time is 10-40 min.

[0021] Further, in step S2, the first mixed ore slurry is stirred at a constant speed during the decompression process.

[0022] Further, in step S2, the stirring speed is 200-800 r / min.

[0023] Further, in step S3, the microbubble flotation column is a known device, and the flotation of the microbubble flotation column adopts a closed circuit process of one roughing, two cleaning and one scavenging, specifically, once roughing, twice cleaning, the concentrate of cleaning I is sent to cleaning II operation, the middlings are returned to the roughing operation, the concentrate of cleaning II is the final concentrate, and the middlings are returned to cleaning I operation.

[0024] The mechanism of micro-nano bubbles in fine particle flotation can be divided into two aspects: one is that the smaller volume increases the probability of collision and adhesion with fine particles, and the other is that micro-nano bubbles can be attached to the gap on the surface of the mineral particles, increasing the hydrophobicity and promoting the agglomeration between particles. Hydrophobic force is a main force between bubbles and particles, according to the DLVO theory, the hydrophobic force is 10-100 times larger than the electrostatic force and van der Waals force, and is the main factor affecting the interaction between bubbles and particles. When the hydrophobic particles are close to each other, the micro-nano bubbles on the surface of the particles will first coalesce to form a micro-nano bubble bridge between the mineral particles. The strong long-range force generated during the bubble coalescence process makes the particles agglomerate, and this force is also called micro-nano bubble bridge capillary force. Micro-nano bubbles are the bridge for the mutual adhesion of bubbles and particles in the flotation process, and the existence of micro-nano bubbles makes the collision and adhesion of the two finally realize the floating.

[0025] Further, the roughing reagent system is: 40 g / t-80 g / t of combined depressant (mass of combined depressant / mass of desliming product), 250 g / t-400 g / t of combined collector (mass of combined collector / mass of desliming product), and no reagent is added in the two times of cleaning in step S3.

[0026] Literature research shows that in the flotation of most oxidized ores, the combination of cationic and anionic collectors has better flotation effect than the single collector alone. The action of the combined collector on the mineral surface is a complex process, and the main mechanisms include: co-adsorption, mutual promotion of adsorption, lengthening of the hydrophobic end, and improvement of the solution environment. In the flotation test of spodumene and feldspar, the presence of sodium oleate promotes the adsorption of sodium dodecyl sulfonate on the surface of spodumene, thereby successfully separating spodumene and feldspar; in the flotation separation system of muscovite and quartz, dodecylamine can promote the adsorption of sodium oleate on muscovite, thereby realizing the effective separation of the two minerals. Generally speaking, the surface tension and critical micelle concentration of the anion-cation combined collector are much lower than those of one of the single components, so the activity is stronger, and smaller and more stable bubbles can be produced, which is beneficial to the flotation process. According to the analysis of the gas-liquid interface fluorescence results, the critical micelle concentration of the anion-cation combined collector is greater than that of any single collector, which shows strong positive synergistic effect. The anion-cation combined collector has better flotation index than the single collector.

[0027] Compared with the prior art, the present application has the following advantages:

[0028] (1) The combined inhibitor of the present application can inhibit the gangue minerals such as quartz, feldspar and fluorite, and does not hinder the hydrophobic flocculation of lepidolite; the cationic and anionic combined collector has good selectivity and collecting performance, and has a certain specific effect on fine-grained lepidolite; the combined inhibitor and the collector have a reinforcing effect on the adsorption of micro-nano bubbles on the surface of lepidolite by strengthening the difference in hydrophobicity between the target mineral and the gangue mineral; the present application combines the combined inhibitor and the cationic and anionic combined collector, adopts the process of slurry adjustment-decompression-lithium flotation, and effectively realizes the efficient recovery of lepidolite in desliming products.

[0029] (2) The process flow of the present application is simple, the dosage of reagents is low, and the economic benefit is high, which has important significance for efficient comprehensive utilization of lithium resources in fine mud. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 is the process flow chart of Example 1 of the present application;

[0031] Figure 2 is the process flow chart of Comparative Example 1 of the present application;

[0032] Figure 3 is the process flow chart of Comparative Example 2 of the present application;

[0033] Figure 4 is the process flow chart of Comparative Example 3 of the present application;

[0034] Figure 5 is the process flow chart of Example 2 of the present application. DETAILED DESCRIPTION

[0035] The present application will be described in detail below with reference to examples. It should be noted that the examples in the present application and the features in the examples can be combined with each other without conflict.

[0036] Example 1

[0037] This example uses a desliming product of a lepidolite ore in Jiangxi, with a low Li2O grade of 0.38%, and the fine mud-20 μm particle size accounts for 45.03%, the main useful mineral is lepidolite, and the gangue minerals are mainly quartz, feldspar, kaolin and calcite, etc., Li is mainly present in mica, and it is easy to form slime due to the presence of a certain amount of clay minerals, resulting in the loss of fine-grained lepidolite.

[0038] The combined depressant ISC (ISC is the code of the combined depressant) in this embodiment is compounded by water glass, caustic starch and carboxymethyl cellulose at a mass ratio of 1:1:2, and the combined collector CSP (CSP is the code of the combined collector) is compounded by dodecylamine, sodium oleate, sodium dodecyl sulfate, oxidized paraffin soap and polyaluminum chloride at a mass ratio of 6:1:2:2:4. The combined collector CSP is used after being configured into a solution with a mass concentration of 5% at 50°C warm water.

[0039] The process flow of this embodiment is shown in Figure 1 The specific steps and reagent system are as follows:

[0040] S1, slurry adjustment: adjust the desliming product into a slurry with a mass concentration of 30%, without adjusting the pH, and then add the combined depressant ISC 50 g / t (mass of the combined depressant / mass of the desliming product) and the combined collector CSP 350 g / t (mass of the combined collector / mass of the desliming product) in sequence, and stir for 3 min, to obtain a mixed slurry of lepidolite and reagents.

[0041] S2, pressure reduction: put the mixed slurry of lepidolite and reagents obtained in step S1 into a pressure reduction device, adjust the system pressure to 0.01 Mpa, and reduce the pressure of the mixed slurry to generate nanobubbles, while keeping the mixed slurry stirred at a constant speed with a rotation speed of 500 rpm, and the pressure reduction operation time is 20 min, to obtain a mixed slurry of lepidolite, reagents and nanobubbles.

[0042] S3, lithium flotation: use the microbubble flotation column to separate the pressure reduction product, adopt one roughing, two cleaning and one scavenging, and do not add extra reagents in the flotation process, to finally obtain lepidolite concentrate and tailings.

[0043] The results of the whole process closed-circuit test are shown in Table 1. The final lepidolite concentrate has a Li2O grade of 1.81% and a Li2O recovery rate of 87.09%, and the final lepidolite tailings have a Li2O grade of 0.06% and a Li2O recovery rate of 12.91%.

[0044] Table 1: Results of whole process closed-circuit test

[0045] Product name Yield / % Li2O grade / % Li2O recovery / % Concentrate 18.28 1.81 87.09 Tails 81.72 0.06 12.91 Fine slime run-of-mine 100.00 0.38 100.00

[0046] Comparative Example 1

[0047] Using the lithium-containing fine slurry in Example 1 as the raw ore, the same reagent system, pressure reduction step and flotation process as in Example 1 are adopted to investigate the influence of different depressants on the operation indexes of the desliming product lithium flotation, and the process flow is shown in Figure 2 Table 2 shows the test results.

[0048] It is evident that without the use of inhibitors, the grade of lithium flotation concentrate is low, with no significant enrichment; using sodium hexametaphosphate as an inhibitor results in low recovery rate and grade of lithium flotation concentrate, which is detrimental to lithium recovery. The use of the combined inhibitor ISC further improves the recovery rate of lithium flotation, demonstrating a significant enhancing effect on improving the recovery of lepidolite.

[0049] Table 2 Results of trials with different inhibitors

[0050]

[0051] Comparative Example 2

[0052] Using the lithium-containing fine mud from Example 1 as the raw ore, and employing the same reagent regimen, depressurization steps, and flotation process as in Example 1, the effects of different collectors on the lithium flotation performance indicators of the deslimed product were investigated. The process flow is as follows: Figure 3 As shown in Table 3, the experimental results are as follows.

[0053] It is evident that using sodium oleate as a collector results in low-grade lithium concentrate with no enrichment. Using dodecylamine as a collector improves the recovery rate and grade of lithium concentrate, but it remains low and unfavorable for lithium recovery. Using a collector composed of sodium oleate and dodecylamine in a 1:4 ratio improves the lithium recovery rate, but it is still lower than that of a combined collector. Using a combined collector further enhances the lithium recovery rate and has a significant strengthening effect on improving lepidolite recovery.

[0054] Table 3 Results of tests with different collectors

[0055]

[0056] Comparative Example 3

[0057] Using the lithium-containing fine mud from Example 1 as the raw ore, and employing the same slurry preparation steps and flotation process as in Example 1, the impact of the depressurization process on the lithium flotation performance indicators of the deslimed product was investigated. The process flow is as follows: Figure 4 As shown ( Figure 4 The left side of the graph shows the process using decompression, and the right side shows the process without decompression. The experimental results are shown in Table 4.

[0058] It is evident that without the depressurization process, the recovery rate and grade of lithium flotation concentrate are improved, but still lower than the Li2O grade and recovery rate obtained using the depressurization process. The absence of a depressurization process is detrimental to lithium recovery. Using the depressurization process further enhances the recovery rate of lithium flotation, significantly strengthening its role in improving lepidolite recovery.

[0059] Table 4. Test results with and without decompression process

[0060]

[0061] Example 2

[0062] The desliming product of a certain lepidolite ore in Daoxian County was used in this example, with a low Li2O grade of 0.23%, and the fine slime of -20 μm accounted for 59.12%. The main gangue minerals included calcite, fluorite, quartz, feldspar, etc. The main valuable metal mineral was lepidolite.

[0063] The process flow of this example was the same as that of Example 1, only the components and dosages of the reagents were different. The combined depressant ISC was compounded by water glass, caustic starch and carboxymethyl cellulose at a mass ratio of 1:1:2. The combined collector CSP was compounded by dodecylamine, sodium oleate, sodium dodecyl sulfate, oxidized paraffin soap and polyaluminum chloride at a mass ratio of 4:1:2:2:3. The combined collector CSP was prepared into a solution with a mass concentration of 5% at 50°C and then used.

[0064] The process flow of this example is shown in Figure 5 The specific steps and reagent system are as follows:

[0065] Step S1, slurry preparation: the desliming product was adjusted to a mass concentration of 34% of the slurry, without adjusting the pH, and then the combined depressant ISC 75 g / t was added and stirred for 3 min, and then the combined collector CSP 400 g / t was added and stirred for 3 min, to obtain a mixed slurry of lepidolite and reagents.

[0066] Step S2, pressure reduction: the slurry product was placed in a pressure reduction device, the system pressure was adjusted to 0.01 Mpa, and the product was subjected to pressure reduction to generate nanobubbles, while the slurry was stirred at a uniform speed, the rotation speed was 500 rpm, and the pressure reduction time was 20 min, to obtain a mixed slurry of lepidolite, reagents and nanobubbles.

[0067] Step S3, lithium flotation: the pressure reduction product was separated using a microbubble flotation column, with one roughing, two cleaning and one scavenging, without additional reagents in the flotation process, to finally obtain a lepidolite concentrate and a tailing.

[0068] The results of the closed-circuit test of the whole process are shown in Table 5. The final lepidolite concentrate had a Li2O grade of 1.52% and a Li2O recovery rate of 76.60%, and the lepidolite tailing had a Li2O grade of 0.11% and a Li2O recovery rate of 23.40%.

[0069] Table 5. Results of closed-circuit test of whole process

[0070] Product name Yield / % Li2O grade / % Li2O recovery / % Concentrate 19.15 1.52 76.60 Tails 80.85 0.11 23.40 Fine slime run-of-mine 100.00 0.38 100.00

[0071] The above embodiments should be understood as being used only for more clearly describing the present application, and not for limiting the scope of the present application, and after reading the present application, various equivalent modifications of the present application by those skilled in the art fall within the scope of the appended claims.

Claims

1. A method of recovering microfine lepidolite from a deslimed product, characterised in that, The method comprises the following steps: S1, slurry preparation: the deslimed product is prepared into a slurry, and a combined depressant and a combined collector are sequentially added and uniformly stirred to obtain a first mixed slurry of lepidolite and reagents; the combined depressant is composed of water glass, caustic starch and carboxymethyl cellulose in a mass ratio of (1-3):(1-3):(2-6); the combined collector is composed of dodecylamine, sodium oleate, sodium dodecyl sulfate, oxidized paraffin soap and polyaluminum chloride in a mass ratio of (4-6):(1-2):(2-5):(2-5):(1-4); S2, pressure reduction: the first mixed slurry obtained in step S1 is placed in a pressure reduction device, and the first mixed slurry is subjected to pressure reduction operation to generate nano bubbles, thereby obtaining a second mixed slurry of lepidolite, reagents and nano bubbles; S3, lithium flotation: the second mixed slurry is separated by using a microbubble flotation column to obtain lepidolite concentrate and tailings.

2. The method of recovering microfine lepidolite from a deslimed product according to claim 1, wherein, In step S1, the deslimed product is prepared into a slurry with a mass concentration of 30%-35%.

3. The method of recovering microfine lepidolite from a deslimed product according to claim 1, wherein The combined collector is used after being configured into an aqueous solution with water at a temperature of 45-55 DEG C, and the mass concentration of the combined collector is 5%-10%.

4. The method of recovering microfine lepidolite from a deslimed product of claim 1, wherein, In step S2, the pressure reduction operation condition is 0.01-0.03 MPa, the pressure reduction operation time is 10-40 min, and the stirring speed of the first mixed slurry during the pressure reduction process is 200-800 r / min.

5. The method of recovering microfine lepidolite from a deslimed product of claim 1, wherein, In step S1, the addition amount of the combined depressant is 40-80 g / t (mass of combined depressant / mass of deslimed product), and the addition amount of the combined collector is 250-400 g / t (mass of combined collector / mass of deslimed product).

6. The method of recovering microfine lepidolite from a deslimed product according to any one of claims 1 to 5, wherein In step S3, the flotation of the microbubble flotation column adopts a closed-circuit process of one roughing, two cleaning and one scavenging.

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