Lithium extraction adsorbent for raw halogen and preparation method thereof
Technical Field
The invention belongs to the technical field of new materials, and particularly relates to a lithium extraction adsorbent for original halogen and a preparation method thereof.
Background
Lithium is the metal with the smallest density in nature, has unique physicochemical characteristics of high specific heat, high conductivity, strong chemical activity and the like, is widely applied to the fields of lithium batteries, aluminum lithium alloys, nuclear energy and the like, has increasingly prominent value particularly along with the rapid development of portable electronic equipment and electric automobiles, and is called as '21 st century energy source new and expensive'. The share of the salt lake lithium resource in the global lithium resource reserve reaches 70-80%, the lithium-containing salt lake resource in China is rich, the salt lake with high magnesium-lithium ratio is taken as the main component, and the method for extracting lithium from the salt lake brine by adopting the low-cost adsorption method has wide application prospect.
The technology for extracting lithium from salt lake brine by adopting an adsorption method is developed earlier abroad, and then patents related to the extraction of lithium from the salt lake brine by the adsorption method are mainly domestic applications, and currently, the core technology in the field is mainly controlled by five countries, namely Japan, China, Korea, United states and Russia. Compared with foreign salt lakes, the lithium resources of the salt lakes in China have the characteristics of high total amount, low lithium grade, high magnesium-lithium ratio, complex associated elements and the like, so that the technical requirements for extracting lithium from the salt lake brine in China are higher than those in foreign countries. At present, the development of domestic salt lake lithium resources is in a primary stage, and the lithium extraction and adsorption market potential is huge.
The core of the adsorption method salt lake lithium extraction technology lies in the research and development of an adsorption material, and the problem of dissolution loss of a manganese adsorbent in a plurality of lithium extraction adsorbents is not completely solved, so that the adsorption quantity is high, but the manganese adsorbent cannot be applied in a large range; although the adsorption amount of the aluminum-based adsorbent is relatively low, the aluminum-based adsorbent is convenient to prepare, high in selectivity, good in stability and long in service life, so that the aluminum-based adsorbent has certain advantages at the present stage.
At present, various reported lithium extraction adsorbents at home and abroad mainly aim at old brine obtained by evaporating and concentrating original brine to remove a large amount of potassium salt and sodium salt, and almost no report is found about an adsorbent for directly extracting lithium from the original brine. The content of original halogen lithium is generally low, and the traditional aluminum-based lithium extraction adsorbent contains a large amount of coexisting ions, when the traditional aluminum-based lithium extraction adsorbent is used for extracting the lithium from the original halogen, the adsorption rate is low, the time required for reaching the work adsorption capacity is long, the lithium extraction efficiency is low, and the application of the aluminum-based lithium extraction adsorbent in the extraction of the original halogen lithium is restricted.
Disclosure of Invention
The technical problem to be solved by the invention is to provide a lithium extraction adsorbent for original halogen and a preparation method thereof, aiming at the defects in the prior art, the preparation method is simple and efficient, the adsorption rate of lithium is effectively improved, the influence of ions coexisting in the original halogen on the performance of the adsorbent is reduced, and a new idea is provided for the development and utilization of salt lake lithium resources.
The invention adopts the following technical scheme:
a preparation method of a lithium extraction adsorbent for original halogen comprises the following steps:
s1, crushing the crosslinked polystyrene resin, soaking the crushed crosslinked polystyrene resin in enough solvent, fully expanding the crushed crosslinked polystyrene resin, and filtering out free solvent to obtain white sphere powder;
s2, mixing the lithium extraction adsorbent active body powder, the adhesive, the white ball powder obtained in the step S1 and the solvent according to the ratio of 1 (0.1-0.5): (0-0.3): (0.5-2.5) uniformly kneading to obtain a mixture;
s3, carrying out extruding, crushing, screening and drying treatment on the mixture obtained in the step S2 to obtain a semi-finished product;
s4, washing the semi-finished product obtained in the step S3 with diluted acid, then washing with water to be neutral, and performing suction filtration to remove free moisture to obtain the lithium extraction adsorbent for the raw halogen.
Specifically, in step S1, the crosslinked polystyrene resin is an unqualified product with a particle size of less than 0.3mm or greater than 1.2mm, which is generated in a factory production process, and the crosslinked polystyrene resin beads with a basic skeleton of styrene and divinylbenzene are pulverized to obtain a powder with a particle size of 60-200 meshes.
Specifically, in step S1 and step S2, the solvent is one or more of N, N-dimethylformamide, ethyl acetate, dichloromethane, chloroform, carbon tetrachloride, dichloroethane, trichloroethane, acetone, or toluene.
Specifically, in step S2, the adhesive includes one or more of polystyrene, epoxy resin, polymethyl methacrylate, polyvinyl chloride, and chlorinated polyvinyl chloride.
Specifically, in the step S3, the screened particle size is 0.6-3.0mm, the drying temperature is 40-100 ℃, and the drying time is 2-6 h.
Specifically, in the step S3, the screened particle size is 0.8-1.2mm, the drying temperature is 40-100 ℃, and the drying time is 2-6 hours.
Specifically, in step S4, the dilute acid is one of hydrochloric acid, nitric acid and sulfuric acid, and the concentration is 0.1 to 1 mol/L.
Furthermore, the concentration of the dilute sulfuric acid is 0.05-0.5 mol/L.
The invention also provides a lithium extraction adsorbent for the original halogen, which is prepared by adopting the method.
Specifically, both the adsorption amount and desorption amount of the lithium extraction adsorbent for orthohalides are 2.7mg/mL or more.
Compared with the prior art, the invention has at least the following beneficial effects:
the invention relates to a preparation method of a lithium extraction adsorbent for raw halogen, which comprises the steps of introducing white ball powder fully expanded by a solvent in the lithium extraction adsorbent forming stage, drying to remove the solvent, reducing the volume of expanded particles, forming gaps between an adsorbent framework and the white ball particles, obtaining a larger pore channel structure, and then treating by dilute acid to widen the pore channel. These larger pores and the solvent volatilization in the drying process, the lithium salt inserted in the preparation of the active body and the fine pores formed by other coated salts in the water washing process form a pore network together. The difficulty of transferring substances in the larger pore passage is obviously smaller than that of the fine pore passage, and the introduction of the larger pore passage effectively shortens the distance of internal diffusion through the fine pore passage, so that the difficulty of internal diffusion of various ions contained in the original halogen in the adsorbent particles is reduced, the lithium adsorption efficiency of the adsorbent is improved, and the time for reaching the work adsorption capacity by adsorption is shortened; the utilization rate of the active body of the lithium extraction adsorbent is improved by the network formed by the larger pore passage and the small pore passage. Because the internal diffusion rate is low, the internal diffusion difficulty of the traditional aluminum-based lithium extraction adsorbent is remarkably increased from the surface to the inside, and the utilization rate of the inner layer of the adsorbent particles is generally low. After the introduction of the larger pore channel, the difficulty of internal diffusion is effectively reduced, the utilization rate of the active body in the inner layer of the adsorbent is improved, and the cost of the lithium extraction adsorbent is reduced to a certain extent.
Furthermore, the white balls used are unqualified products with grain diameter generated in the production process of the resin, and the purpose of solid waste recycling is achieved. In general, in order to ensure the resin properties, it is required that the particle size of the white balls is within a specific range, and when the white balls are produced by a conventional suspension polymerization process, the particle size distribution of the obtained white balls is generally wide, and some defective products having a larger or smaller particle size are inevitably produced. These rejects are either disposed of as solid waste or applied to specific areas, but these areas are generally in smaller demand and therefore often result in an undesirable backlog. The presence of rejects increases the production costs and it is sought to recycle them. The white ball will expand in the organic solvent, the volume will increase obviously, and the original grain size will be recovered after the solvent is removed. By utilizing the characteristic of the white ball, white ball powder expanded by the organic solvent is introduced into the forming process of the lithium extraction adsorbent to form a larger pore passage. The technical route of taking the white balls with unqualified particle sizes as the pore-foaming agent of the lithium extraction adsorbent improves the performance of the lithium extraction adsorbent, realizes the recycling of solid wastes generated in the suspension polymerization process, achieves two purposes at one stroke, and achieves the aim of green sustainable production.
Furthermore, the solvent used in steps S1 and S2 can fully swell the white ball powder, and can dissolve or swell the binder, so that the materials can be mixed more uniformly in the kneading stage, and the white ball powder can be easily removed in the drying stage to shrink the volume of the white ball powder to form larger pores.
Furthermore, the adhesive used in step S2 is easily dissolved or swelled by the solvent of the present invention, has good adhesion to the active adsorbent body, is inert in the original halogen, provides a stable support for the active adsorbent body, and significantly improves the service life of the adsorbent.
Furthermore, the particle size of the adsorbent is controlled to be 0.6-3.0mm, so that the adsorption performance and the service life of the adsorbent can be considered. In general, as the particle size increases, the distance of ion diffusion in the adsorbent in brine increases, and the time for adsorption and desorption increases, so that the performance of the adsorbent can be improved by reducing the particle size under the same condition; however, the adsorbent having an excessively small particle size suffers a large mass loss due to brine washing, and the bed layer thereof has a large flow resistance against brine, so that the particle size must be controlled within a reasonable range. The drying temperature is set to be 40-100 ℃, the drying time is set to be 2-6 h, the higher temperature treatment time is shorter or the lower temperature treatment time is longer, and the influence on the performance of the adsorbent due to the damage of crystal water in the active body of the adsorbent can be avoided while the solvent is removed.
Furthermore, the particle size of the adsorbent is controlled to be 0.8-1.2mm, the particle size range is obviously reduced compared with 0.6-3.0mm, and the adsorption and desorption efficiency is obviously improved. In general, the internal diffusion distance of brine in the large-particle-size adsorbent is longer than that of the small-particle-size adsorbent, so that the large-particle-size adsorbent needs a longer time to be saturated in adsorption or completely desorbed under the same conditions. If the particle size range is large, the adsorption saturation or sufficient desorption time of the adsorbent particles with different particle sizes is different in the use process, so that the smaller the particle size range of the adsorbent is, the narrower the absorption peak and the desorption peak of lithium in the use process are, the higher the peak value is, and the higher the adsorption and desorption efficiency is.
Further, the matrix of the aluminum-based lithium extraction adsorbent is amorphous aluminum hydroxide, is an amphoteric compound, and can be dissolved in a strong acidic or alkaline environment, and the dilute acid is used in S7 to widen the pore path of the adsorbent, based on the principle. The concentration of the dilute acid is controlled, the dissolution degree of the amorphous aluminum hydroxide can be effectively controlled, and the damage to the matrix structure of the adsorbent is avoided.
Further, sulfuric acid is a strong binary acid, and is generally a solution of the same acidity, and the concentration of sulfuric acid is half of that of a strong monobasic acid such as hydrochloric acid or nitric acid.
The lithium extraction adsorbent for the original halogen effectively improves the adsorption rate of lithium, reduces the influence of ions coexisting in the original halogen on the performance of the adsorbent, and provides a new idea for the development and utilization of salt lake lithium resources.
In conclusion, the invention takes the solid wastes in the resin production process as the pore-forming agent to prepare the lithium extraction adsorbent for the raw halogen with rich pore channel structures.
The technical solution of the present invention is further described in detail by the accompanying drawings and embodiments.
Drawings
FIG. 1 is a flow chart of the present invention.
Detailed Description
The invention provides a preparation method of a lithium extraction adsorbent for original halogen, which comprises the following steps:
s1, crushing 0-0.3 part by mass of crosslinked polystyrene resin (white balls for short, provided by Shaanxi blue deep special resin Co., Ltd.), soaking the crushed resin in sufficient solvent, fully expanding the soaked resin, and filtering out free solvent;
the white balls are unqualified products with particle size produced in the production process of a factory, the basic skeleton is styrene and divinylbenzene, and the particle size of the powder obtained after crushing is 60-200 meshes.
The solvent includes N, N-dimethylformamide, ethyl acetate, dichloromethane, chloroform, carbon tetrachloride, dichloroethane, trichloroethane, acetone, toluene and the like, and the same solvent is used for the expansion and kneading processes.
S2, mixing the active lithium extraction adsorbent powder (provided by Shaanxi blue deep special resin Co., Ltd.), the adhesive, the expanded white ball powder (dry weight) and the solvent according to the ratio of 1 (0.1-0.5): (0-0.3): (0.5-2.5) uniformly kneading to obtain a mixture;
the binder comprises one or more of polystyrene, epoxy, polymethyl methacrylate, polyvinyl chloride, chlorinated polyvinyl chloride, and the like.
The solvent includes N, N-dimethylformamide, ethyl acetate, dichloromethane, chloroform, carbon tetrachloride, dichloroethane, trichloroethane, acetone, toluene and the like, and the same solvent is used for the expansion and kneading processes.
S3, carrying out extruding, crushing, screening and drying treatment on the mixture obtained in the step S2 to obtain a semi-finished product;
sieving particles with the particle size of 0.6-3.0mm, preferably 0.8-1.2mm, and drying at 40-100 ℃ for 2-6 h to obtain a semi-finished product.
S4, washing the semi-finished product obtained in the step S3 with diluted acid, finally washing with water to be neutral, and performing suction filtration to remove free moisture to obtain the finished product.
The diluted acid is one of hydrochloric acid, nitric acid and sulfuric acid, the concentration is 0.1-1 mol/L, and the concentration of the diluted sulfuric acid is 0.05-0.5 mol/L.
The lithium extraction adsorbent for the original halogen prepared by the method has a rich pore channel structure, and the adsorption quantity and desorption quantity of lithium in the original halogen are both more than or equal to 2.7 mg/mL.
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of the embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
30.0g of white balls (supplied by Shaanxi blue deep Special resin Co., Ltd.) were pulverized into powder having a particle size of 200 mesh, sufficiently expanded with a sufficient amount of carbon tetrachloride, and then free carbon tetrachloride was filtered off.
100.0g of lithium extraction adsorbent active body powder (supplied by Shaanxi blue deep Special resin Co., Ltd.), 30.0g of polyvinyl chloride, expanded white ball powder and 150.0g of carbon tetrachloride were uniformly kneaded. Extruding, crushing and screening, collecting all particles with the particle size of 0.8-1.2mm, and drying for 2 hours at 100 ℃ to obtain a semi-finished product. Washing the semi-finished product with 1mol/L diluted hydrochloric acid, then washing the semi-finished product with pure water to be neutral, and filtering the solution to remove free moisture to obtain a finished product 1.
Example 2
15.0g of white balls (supplied by Shaanxi blue deep Special resins Co., Ltd.) were pulverized into powder having a particle size of 130 mesh, sufficiently expanded with a sufficient amount of chloroform, and then free chloroform was filtered off.
100.0g of lithium extraction adsorbent active body powder (supplied by Shaanxi blue deep Special resin Co., Ltd.), 10.0g of polyvinyl chloride, expanded white sphere powder and 150.0g of chloroform were uniformly kneaded. Extruding, crushing and screening, collecting all particles with the particle size of 0.8-1.2mm, and drying at 70 ℃ for 4h to obtain a semi-finished product. Washing the semi-finished product with 0.5mol/L dilute hydrochloric acid, then washing with pure water to be neutral, and filtering to remove free moisture to obtain a finished product 2.
Example 3
30.0g of white balls (supplied by Shaanxi blue deep Special resins Co., Ltd.) were pulverized into powder having a particle size of 200 mesh, sufficiently expanded with a sufficient amount of dichloroethane, and then filtered to remove free dichloroethane.
100.0g of lithium extraction adsorbent active body powder (supplied by Shaanxi blue deep Special resin Co., Ltd.), 50.0g of polymethyl methacrylate, expanded white sphere powder, and 250.0g of dichloroethane were uniformly kneaded. Extruding, crushing and screening, collecting all particles with the particle size of 0.8-1.2mm, and drying for 2 hours at 100 ℃ to obtain a semi-finished product. Washing the semi-finished product with 1mol/L diluted hydrochloric acid, then washing the semi-finished product with pure water to be neutral, and filtering the solution to remove free moisture to obtain a finished product 3.
Example 4
15.0g of white balls (supplied by Shaanxi blue deep specialty resins Co., Ltd.) were pulverized into a powder having a particle size of 60 mesh, sufficiently swollen with a sufficient amount of dichloromethane, and then free dichloromethane was filtered off.
100.0g of lithium extraction adsorbent active body powder (supplied by Shaanxi blue deep Special resin Co., Ltd.), 30.0g of polystyrene, expanded white sphere powder, and 250.0g of methylene chloride were uniformly kneaded. Extruding, crushing and screening, collecting all particles with the particle size of 0.6-3.0mm, and drying for 2 hours at 100 ℃ to obtain a semi-finished product. And (3) washing the semi-finished product with 0.1mol/L dilute nitric acid, then washing the semi-finished product with pure water to be neutral, and performing suction filtration to remove free moisture to obtain a finished product 4.
Example 5
100.0g of lithium extraction adsorbent active body powder (supplied by Shaanxi blue deep Special resin Co., Ltd.), 10.0g of polystyrene and 50.0g of methylene chloride were kneaded uniformly. Extruding, crushing and screening, collecting all particles with the particle size of 0.8-1.2mm, and drying at 40 ℃ for 6h to obtain a semi-finished product. And (3) washing the semi-finished product with 0.5mol/L dilute nitric acid, then washing the semi-finished product with pure water to be neutral, and performing suction filtration to remove free moisture to obtain a finished product 5.
Comparative example
100.0g of lithium extraction adsorbent active body powder (supplied by Shaanxi blue deep Special resin Co., Ltd.), 30.0g of polyvinyl chloride and 200.0g of methylene chloride were kneaded uniformly. Extruding, crushing and screening out particles with the particle size of 0.8-1.2mm, drying for 6 hours at 40 ℃, washing with pure water, and filtering to remove free moisture to obtain a comparison product.
The lithium extraction adsorbent prepared by the method is characterized by comprising the following specific steps:
taking 10.0mL of a lithium extraction adsorbent sample which is activated by pure water, placing the sample in a 500.0mL conical flask, adding 300mL of a certain salt lake original halogen (the lithium content is 130mg/L), oscillating for 2h at room temperature, taking samples oscillating for 0.5h and 2h, measuring the lithium content, and calculating the adsorption capacity; filtering free brine during desorption, adding 300mL of pure water, oscillating for 2h at room temperature, taking samples oscillating for 0.5h and 2h, measuring the lithium content, and calculating the desorption amount. Repeating for several cycles, and obtaining the adsorption quantity and the adsorption quantity of the sample after the data are stable. The lithium content was determined using a steel Minakg Plasma 2000 model full-spectrum inductively coupled Plasma spectrometer.
TABLE 1 statistical table of adsorption and desorption amounts of lithium extraction adsorbents
As can be seen from table 1, the adsorption amount and the desorption amount of the samples prepared in examples 1 to 4 of the present invention reach 80% or more and 86% or more of the adsorption amount and the desorption amount of 2h, respectively, in 0.5h, the adsorption amount and the desorption amount of the samples prepared in example 5 reach 72% or 81% of the adsorption amount and the desorption amount of 2h, respectively, and the adsorption amount and the desorption amount of the samples prepared in comparative example reach only 50% or 63% of the adsorption amount and the desorption amount of 2h, respectively, in 0.5 h. According to the data in table 1, the adsorption and desorption performances of the samples prepared in examples 1 to 4 are optimal, and the samples in example 5 are inferior to those in the comparative example, so that the following conclusion can be drawn: compared with the traditional lithium extraction adsorbent, the lithium extraction adsorbent prepared by the technology has higher adsorption and desorption efficiency and adsorption and desorption amount.
The conventional aluminum-based lithium extraction adsorbent only has relatively fine pore passages, and the pore passages are formed in the drying process by solvent volatilization, lithium salt inserted in the preparation of an active body and other coated salts in the washing process. The invention utilizes the characteristic that white balls can expand in an organic solvent, the volume is obviously increased, the original particle size is recovered after the solvent is removed, white ball powder which is fully expanded by the solvent is introduced in the forming process of the lithium extraction adsorbent, and the pore channel is further widened by means of the change of the particle volume of the white ball powder before and after drying and the treatment of dilute acid, so that a larger pore channel is finally constructed. Thereby effectively reducing the difficulty of internal diffusion and improving the adsorption efficiency of the adsorbent and the utilization rate of the inner active body.
In the embodiments 1 to 4, the white ball powder fully expanded by the solvent is introduced in the lithium extraction adsorbent forming stage and is treated by combining with the dilute acid; example 5 treatment with dilute acid only; the comparative example did not incorporate white ball powder nor treated the adsorbent with dilute acid. Compared with the comparative sample, the sample of the embodiment has richer pore channel structures and larger specific surface area, and can perform substance exchange with the liquid phase more quickly and sufficiently during the use process, so that the sample of the embodiment has higher adsorption and desorption rates and higher utilization rate.
In summary, the lithium extraction adsorbent for the original halide and the preparation method thereof provided by the invention take the resin production solid waste as the pore-forming agent to prepare the lithium extraction adsorbent for the original halide with rich pore channel structures, and compared with the traditional lithium extraction adsorbent, the lithium extraction adsorbent has higher adsorption and desorption efficiency and adsorption and desorption capacity, and is technically feasible.
The above-mentioned contents are only for illustrating the technical idea of the present invention, and the protection scope of the present invention is not limited thereby, and any modification made on the basis of the technical idea of the present invention falls within the protection scope of the claims of the present invention.