CN113088695A - Gradient simulated moving bed method for large-scale combined extraction of boron and lithium in brine - Google Patents

Gradient simulated moving bed method for large-scale combined extraction of boron and lithium in brine Download PDF

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CN113088695A
CN113088695A CN202110268267.9A CN202110268267A CN113088695A CN 113088695 A CN113088695 A CN 113088695A CN 202110268267 A CN202110268267 A CN 202110268267A CN 113088695 A CN113088695 A CN 113088695A
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lithium
boron
brine
fixed bed
zone
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李平
张云波
邵历强
杨颖�
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East China University of Science and Technology
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
    • C22B7/006—Wet processes
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B35/00—Boron; Compounds thereof
    • C01B35/08—Compounds containing boron and nitrogen, phosphorus, oxygen, sulfur, selenium or tellurium
    • C01B35/10—Compounds containing boron and oxygen
    • C01B35/1045—Oxyacids
    • C01B35/1054—Orthoboric acid
    • C01B35/1081—Preparation by working up other natural sources, e.g. seawater
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
    • C01D15/00—Lithium compounds
    • C01D15/08—Carbonates; Bicarbonates
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B26/00—Obtaining alkali, alkaline earth metals or magnesium
    • C22B26/10—Obtaining alkali metals
    • C22B26/12—Obtaining lithium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
    • C22B3/02—Apparatus therefor
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
    • C22B3/20—Treatment or purification of solutions, e.g. obtained by leaching
    • C22B3/22—Treatment or purification of solutions, e.g. obtained by leaching by physical processes, e.g. by filtration, by magnetic means, or by thermal decomposition
    • C22B3/24—Treatment or purification of solutions, e.g. obtained by leaching by physical processes, e.g. by filtration, by magnetic means, or by thermal decomposition by adsorption on solid substances, e.g. by extraction with solid resins
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Abstract

The invention provides a gradient simulated moving bed method for large-scale combined extraction of boron and lithium in brine, which comprises the following steps: the fixed beds are filled with adsorbents, the four material input ports and the four material output ports divide the fixed beds into four areas, each area comprises a plurality of fixed beds which are connected in series for operation, open circuits are formed among the areas, and the whole system is in a state of four-area open circuits; low-grade boron-lithium brine enters from the area III, and after the boron-lithium is adsorbed by the fixed bed adsorbent, the lean brine is discharged into a salt pan; after the valve is switched, the fixed bed is circularly operated from the zone III → the zone II → the zone I → the zone IV → the zone III … … in sequence, so that the co-extraction of the boron and the lithium in the brine is realized, and the high-quality boron and lithium solution is continuously obtained at an extraction port. Provides a gradient simulated moving bed adsorption method for jointly extracting boron and lithium in brine, and reduces the extraction cost and energy consumption of boron or lithium.

Description

Gradient simulated moving bed method for large-scale combined extraction of boron and lithium in brine
Technical Field
The invention relates to the technical field of extraction, enrichment and concentration of valuable elements of boron and lithium in salt lake brine, in particular to a large-scale combined extraction method of boron and lithium in brine.
Background
With the increasing prominence of global resources and environmental problems, lithium is one of the important materials of green energy in the new century, and the development and application of lithium are widely concerned. With the development and application of lithium power batteries for automobiles, the lithium resources will be in short supply in the future, so that the lithium resources are regarded as important strategic resources by various countries. Boron and compounds thereof have a very important position in the fields of modern industry and science and technology, and are widely applied to the fields of electronics, chemical industry, medicine, glass, ceramics, nuclear industry, aerospace and the like. Boron is a novel resource, the consumption of which is increased year by year, and has become an indispensable important chemical product in modern industry. However, boron ore and lithium ore in China are short in resources and cannot meet the industrial production requirements. However, the salt lake brine in China is rich in a large amount of boron and lithium valuable elements and is a valuable boron and lithium resource. The Tibet Zambuya salt lake, the Chadada basin, the east Ginell salt lake and the SitaiGinell salt lake brine contain more than 59 elements, wherein Li, B, Cs, Br, K, Rb and the like have close symbiotic relationship, the content of the elements increases along with the mineralization degree of the lake water, and the brine has huge reserves and development value.
Various researchers in various countries successfully develop various lithium extraction processes aiming at the characteristics of different salt lake brines. The most common process is that lithium in original brine is concentrated by solarization and evaporation, and then the lithium in the concentrated brine is separated and extracted by adopting a proper separation technology to finally prepare lithium carbonate. The process for separating lithium from brine after being evaporated and concentrated by sun mainly comprises a solar pond temperature-rising lithium precipitation method, a calcination method, an adsorption method, a solvent extraction method and the like. In practical application, the solar cell temperature-rising lithium precipitation method is mainly suitable for extracting lithium from carbonate type brine with high lithium grade and low magnesium-lithium ratio; the precipitation method is more suitable for extracting lithium from brine with medium-low magnesium-lithium ratio; the adsorption method has the potential of being applied to the extraction of lithium in brine with low lithium concentration and high magnesium-lithium ratio. There are also many methods for extracting boron from salt lake brine, such as acidification precipitation method, solvent extraction method and adsorption method, wherein the acidification precipitation method is suitable for brine system with high boron content, the process operation is simple, the cost is low, but the recovery rate is low, and the solvent extraction method can be combined to extract boron. The solvent extraction method is suitable for brine systems with the boron concentration of 2g/L-18 g/L. The adsorption method is suitable for a salt lake brine system with low boron concentration, and has the advantages of high boron selectivity, high recovery rate and the like.
Because the salt lake brine has low boron and lithium grade, high magnesium and lithium ratio and high content of alkali metal and alkaline earth metal, the extraction cost and energy consumption of the boron and lithium are high, and the industrialization process is limited. In recent years, a plurality of scholars apply for patents, and propose a combined extraction technology of boron and lithium valuable elements in salt lake brine, so that the extraction cost and energy consumption of a single product (boron or lithium) are reduced, the market competitiveness is improved, and the industrialization process of the utilization of boron and lithium resources in the salt lake brine is promoted. Representative examples are:
(1) the Z1201310451528.6 patent discloses a method for comprehensively utilizing potassium, boron and lithium in salt lake brine, which adopts an acidification process to adjust the pH value of the brine, and adopts a solvent extraction method to extract boric acid from the acidified brine; the raffinate enters a sodium salt pool, is subjected to solarization and evaporation to separate out sodium salt, and then enters a potassium salt pool to separate out potassium mixed salt; and (4) extracting lithium carbonate from the lithium-enriched potassium separation mother liquor by a precipitation method.
(2) The CN108264064A patent discloses a comprehensive recycling method of boron and lithium in brine. Firstly, after a large amount of boron is precipitated by evaporation concentration and an acid method, deep separation and recovery are carried out on the boron left in brine after boron precipitation by adopting an extraction or adsorption method; after boron is removed, the brine is subjected to precipitation of calcium and most of magnesium by adopting Na2CO3, and then deep precipitation and purification of the rest magnesium are performed by using NaOH; and separating and recovering NaCl and/or KCl from the brine after purifying calcium and magnesium by evaporation crystallization and/or cooling crystallization, and then precipitating the lithium-containing concentrated solution by adopting Na2CO3 to extract lithium carbonate.
(3) The CN108584995A patent discloses a method for comprehensively extracting lithium, potassium and boron from oil field brine, which comprises the following process flows: pretreating, evaporating and crystallizing to separate out sodium salt to obtain sodium extraction mother liquor, evaporating and crystallizing the sodium extraction mother liquor to separate out potassium salt to obtain potassium extraction mother liquor, removing impurities from the potassium extraction mother liquor by using lime milk and mirabilite to obtain potassium extraction mother liquor after impurity removal, adding hydrochloric acid or sulfuric acid into the potassium extraction mother liquor after impurity removal to obtain crude boric acid and crude lithium-containing mother liquor, evaporating and concentrating the crude lithium-containing mother liquor, chelating or adsorbing to purify and remove impurities to obtain refined lithium-rich mother liquor, and adding alkali into the refined lithium-rich mother liquor to precipitate and wash to obtain crude lithium carbonate.
(4) The CN103523801A patent discloses a method for jointly extracting potassium, boron and lithium from chloride type potassium-containing underground brine, sodium chloride is separated out by adopting an evaporation process, and brine is enriched; concentrating by a certain multiple, and extracting boric acid by an ion exchange method; precipitating calcium from the adsorbed solution with mirabilite to eliminate the influence of calcium on the subsequent lithium extraction process; evaporating the calcium precipitation mother liquor at high temperature to separate out sodium salt, and crystallizing at low temperature to separate out potassium salt; and extracting lithium carbonate from the potassium separation mother liquor by a precipitation method.
(5) The CN108342595A patent discloses a co-extraction method of boron and lithium in brine, which adopts a mixed extraction system to synchronously extract boron and lithium in brine, so as to realize the separation between boron and lithium and a brine matrix. Then, the lithium and the boron in the organic phase are back-extracted by respectively adopting an acidic solution and an alkaline solution, so that the separation between the boron and the lithium is realized. The lithium-containing strip liquor is concentrated, cooled and crystallized to prepare lithium chloride or precipitate to prepare lithium carbonate, and the boron-containing strip liquor is directly concentrated and crystallized to prepare borax or is concentrated and crystallized to prepare boric acid after acidification.
(6) The CN 103031448B patent relates to a method for pre-enriching and separating lithium and boron in salt lake brine by liquid-liquid three-phase extraction, which comprises the following steps: adding a water-soluble synergist into a salt lake concentrated brine solution, adjusting the pH value of brine, adding a water-soluble high-molecular polymer, and fully mixing at room temperature to obtain an upper-layer liquid phase system and a lower-layer liquid phase system; then adding an organic extracting agent, and mixing to obtain an upper, middle and lower three-layer liquid phase system. Taking the upper phase and the middle phase of the three-liquid phase system, and respectively back extracting and recovering lithium and boron in the upper phase and the middle phase. The method can realize one-step extraction, namely simultaneously enriching and extracting lithium and boron from the salt lake brine with high magnesium-lithium ratio, and can separate the lithium and boron from a large amount of coexisting magnesium, calcium and other impurity metal ions in the brine. Lithium and boron are selectively enriched in the three-liquid-phase system, and the two phases in the system can be respectively separated, so that the primary separation can be realized for subsequent purification and refining.
In view of low grade of boron and lithium, high ratio of magnesium and lithium and high content of alkali metal and alkaline earth metal in salt lake brine in China, practice proves that the method for directly extracting low-concentration boron and lithium valuable elements in the brine by adopting an adsorption method has obvious advantages, and the process can separate a large amount of coexisting magnesium, calcium and other impurity metal ions in the boron and lithium and the brine. Desorbing the acid to obtain liquid rich in lithium and boron, adding hydrochloric acid for crystallization and separation to obtain crude boric acid, evaporating and concentrating the crude lithium-containing mother liquor, and adding lithium carbonate to obtain crude lithium carbonate. The invention directly co-extracts lithium and boron in brine from salt lake brine with high magnesium-lithium ratio by adopting an adsorption method, reduces the extraction cost and energy consumption of a single product (boron or lithium), and adopts an advanced gradient simulated moving bed adsorption separation technology to continuously extract boron and lithium in the brine by adopting a key technology.
Disclosure of Invention
Therefore, the technical problem to be solved by the invention is to provide a gradient simulated moving bed adsorption method for jointly extracting boron and lithium in brine, so that the extraction cost and energy consumption of a single product (boron or lithium) are reduced.
The technical scheme of the invention is that a gradient simulated moving bed method for large-scale combined extraction of boron and lithium in brine is characterized in that: a plurality of fixed bed systems are adopted; each fixed bed is filled with an adsorbent; the four material input ports and the four material output ports divide the fixed bed system into four areas, each area comprises at least one fixed bed which is operated in series, open circuits are formed among the areas, and the whole system is in a four-area open circuit state;
zone I: in the acid desorption area, eluting the boron and lithium elements adsorbed by the adsorbent in the fixed bed by using dilute acid to obtain a high-grade boron and lithium solution;
zone II: a primary water washing zone for washing the ions and impurities remaining in the fixed bed with a small amount of water; the ions are potassium, sodium, calcium, magnesium and the like;
zone III: in the adsorption zone, the brine containing boron and lithium is input into a fixed bed filled with an adsorbent, and the boron and lithium in the brine are adsorbed and extracted by the adsorbent in the tower; the lean brine is discharged to a designated place, such as a salt pan, and is subjected to subsequent recovery; the sample can be collected in a container in a laboratory for later use.
Zone IV: a secondary water washing area, which uses a small amount of water to wash the remained dilute hydrochloric acid in the tower;
after a certain time interval, the input and output material port synchronously moves a fixed bed along the fluid flowing direction; after the valves are switched, one fixed bed in each zone moves to the other zone, and other fixed beds correspondingly move to a position in a direction opposite to the fluid flowing direction, so that countercurrent flow is formed between the adsorbent fixed phase and the fluid flowing phase;
the method comprises the following steps:
(1) the low-grade boron-lithium brine enters the zone III and flows through each fixed bed of the zone III in sequence;
filling an adsorbent in the tower in the area III to adsorb boron and lithium in the brine, and discharging the brine to a salt pan;
in practical application, the brine after boron and lithium recovery is discharged to a salt pan, and other useful components are also discharged for subsequent recovery. In laboratory experiments, the product can be collected by a container for later use.
(2) After boron and lithium in brine are extracted by an adsorbent in a fixed bed, the brine is shifted to a zone II for primary water washing after being switched by a valve, and other ions retained in a tower are removed;
(3) after impurity ions retained in the fixed bed are washed out, the impurities are switched by a valve and then are moved to a region I for acid hydrolysis and adsorption of boron and lithium on the adsorbent, and a high-quality boron and lithium solution is obtained from an extraction port;
(4) the fixed bed after being desorbed by dilute acid is switched to move to a region IV through a valve for secondary water washing, and dilute acid liquid retained in the desorption tower is recovered;
(5) and the fixed bed of the secondary water washing is moved to an adsorption zone III through valve switching, and the boron and the lithium in the brine are continuously adsorbed and recovered, and are continuously and circularly operated in sequence.
The fixed bed is also called an adsorption column after being filled with an adsorbent, and is also called a desorption column at the time of desorption.
The whole system forms a four-zone open circuit state. Each zone assumes a different task.
At a set valve switching time interval, a fixed bed is sequentially switched along the fluid flow direction through the inlet and outlet material positions, so that countercurrent flow is formed between the adsorbent fixed phase and the fluid flow phase, and the heat transfer and mass transfer efficiency is enhanced. Meanwhile, through the switching of the positions of the inlet and outlet materials, in the circulating process, each fixed bed sequentially enters an adsorption area, a primary water washing area, an acid hydrolysis and adsorption area and a secondary water washing area.
After a certain time interval, the input and output material port synchronously moves a fixed bed along the fluid flowing direction; after the valves are switched, one fixed bed in each zone is moved to another zone, and the other fixed beds are correspondingly moved to a position opposite to the direction of fluid flow.
All fixed beds were switched once to one cycle. If the system contains 12 fixed beds and the input and output ports move one fixed bed at a time, then switching 12 times is a cycle. After 20 cycles, the system can reach a stable operation state, and the continuous extraction of the brine boron and lithium is realized.
The gradient simulated moving bed process for large scale combined extraction of boron and lithium from brine according to the present invention preferably comprises at least one fixed bed per zone; the number of fixed beds is at least 4. The number of fixed beds in each zone can be different, and the number of the fixed beds can be increased to improve the separation efficiency under the condition that the operation pressure of the system allows; it is recommended that more than 2 fixed beds be operated in series per separation zone.
According to the gradient simulated moving bed method for large-scale combined extraction of boron and lithium in brine, the adsorbent is preferably one or two of boron adsorbent and lithium adsorbent; the adsorbent is filled in a fixed bed, and a single adsorbent is filled in the fixed bed; and filling the boron adsorbent and the lithium adsorbent in the fixed bed, wherein the filling comprises mixed filling and layered filling.
The ratio of boron sorbent to lithium sorbent is determined by the boron-lithium content of the brine and the properties of the sorbent selected. Layered filling, the boron adsorbent and the lithium adsorbent can be filled in the upper layer and the lower layer without special difference.
According to the gradient simulated moving bed method for large-scale combined extraction of boron and lithium in brine, the boron adsorbent is preferably meglumine chelate resin.
According to the gradient simulated moving bed method for large-scale combined extraction of boron and lithium in brine, the lithium adsorbent is preferably a titanium-based lithium ion sieve and a manganese-based lithium ion sieve.
According to the gradient simulated moving bed method for large-scale combined extraction of boron and lithium in brine, the low-grade boron and lithium brine preferably comprises the following components in percentage by weight: the lithium content is 50 mg/L-300 mg/L, and the boron content is 50 mg/L-300 mg/L. The content of other potassium, sodium, calcium and magnesium ions is not limited, and the other ions can be the same as the natural brine in composition and have a pH value of 3-7. And a small amount of sodium bicarbonate is added into the brine to neutralize hydrogen ions released in the ion exchange adsorption process.
According to the gradient simulated moving bed method for large-scale combined extraction of boron and lithium in brine, preferably, in the step (1), after the low-grade boron and lithium brine enters the adsorption zone, the brine input amount is adjusted, the brine temperature is 10-40 ℃, and the recovery rates of boron and lithium in the brine are controlled to be more than 70%.
According to the gradient simulated moving bed method for large-scale combined extraction of boron and lithium in brine, the flow rate of input water is preferably adjusted in the step (2), the water temperature is 10-40 ℃, and the impurity ion elution rate in brine retained in an adsorption tower is more than 90%.
According to the gradient simulated moving bed method for large-scale combined extraction of boron and lithium in brine, preferably, in the step (3), the desorbent is a dilute hydrochloric acid solution, the concentration range is 0.2mol/L HCl-0.5 mol/L HCl, the temperature is 10-40 ℃, and the flow of input dilute hydrochloric acid is adjusted, so that the desorption rate of boron and lithium is more than 80%.
Preferably, in the step (4), the secondary washing is carried out, the water temperature is 10-40 ℃, the dilute hydrochloric acid retained in the washing tower is used, and the pH value of the effluent is controlled to be 3-7.
According to the gradient simulated moving bed method for large-scale combined extraction of boron and lithium in brine, the desorbent is preferably a dilute hydrochloric acid solution, the concentration range of the desorbent is 0.2mol/L HCl-0.5 mol/L HCl, and the temperature is 10-40 ℃.
Introduction of high-efficiency boron lithium adsorbent:
the titanium-series lithium ion sieve and the manganese-series lithium ion sieve both have good performance of extracting lithium ions in brine, other coexisting ions in the brine, such as sodium, potassium, calcium, magnesium and the like, almost have no adsorption capacity, and the ion sieves have good selectivity. The lithium ion content of the brine was 200mg/L, pH 7, 25 ℃, and the amount of lithium adsorbed by the ion sieve was about 10mg (Li +)/g (ion sieve). The lithium ion mechanism of the lithium ion sieve for absorbing lithium ions in brine belongs to ion exchange adsorption of hydrogen ions and lithium ions. The hydrogen ions on the ion sieve can be replaced during the adsorption of the lithium ions in the brine, and the replaced hydrogen ions enter the brine, so that the pH value in the brine can be reduced, the brine is acidic, the lithium adsorption capacity of the ion sieve is reduced, and the timely removal of the hydrogen ions accumulated in the brine is very critical. The ion sieve for adsorbing lithium ions can be desorbed by dilute hydrochloric acid (0.2-0.5 mol/L HCl), the lithium desorption rate is over 90 percent, and lithium-rich crude mother liquor can be obtained after desorption. And (3) evaporating, concentrating and removing impurities from the crude lithium-containing mother liquor, and adding lithium carbonate to obtain crude lithium carbonate. Lithium adsorption and acid desorption in the brine can be carried out at room temperature, and the temperature is 20-40 ℃.
The meglumine chelate resin has the characteristics of high adsorption rate, large adsorption capacity, boron selective adsorption, good desorption performance and good cycle stability, and can be suitable for boron selective extraction in brine. The meglumine chelate resin is prepared by utilizing the complexation reaction of a meglumine group and borate, and separating boron from brine. Boron is complexed and adsorbed with 1, 2-position hydroxyl on meglumine in the form of borate in aqueous solution; when hydrochloric acid is desorbed, a large amount of H + in the solution restores the dihydroxy on the function of the meglumine again, and the boric acid returns to the solution and is desorbed. The boron adsorption amount reaches about 10mg (B)/g (resin), the adsorption selectivity is high, the adsorption rate is high, the good adsorption performance is kept under the temperature condition of 25 ℃ to 65 ℃, neutral and alkaline solutions are favorable for the adsorption of boron, the resin can be desorbed under the condition of 0.2 mol/L-0.5 mol/L hydrochloric acid or sulfuric acid, and the cyclic adsorption desorption performance is stable. Compared with the foreign methylamine chelate resin (the brands are IRA-743 and D-05 resin), the domestic meglumine chelate resin (the brands are LSC-800, ZG-99, D403, D564 and XSC-700 resin) has low price, good adsorption performance and market competitiveness.
Introduction of boron and lithium co-extraction process in brine:
the adsorption and desorption conditions of the lithium ion sieve and the meglumine chelating resin are basically the same, boron or lithium in salt lake brine is adsorbed in high selectivity under the neutral or alkaline condition, and the adsorbed boron and lithium can be desorbed by dilute acid. And (3) desorbing the obtained high-concentration boron-lithium aqueous solution, further adding hydrochloric acid for crystallization and separation to obtain crude boric acid, and adding lithium carbonate to obtain crude lithium carbonate. Provides sufficient conditions for co-extraction of boron and lithium in brine.
First, a lithium ion sieve (lithium adsorbent) and a meglumine chelate resin (boron adsorbent) are filled in a fixed bed in three ways, as shown in fig. 1. The fixed bed is filled with a single adsorbent (figure 1a and figure 1b), a boron adsorbent or a lithium adsorbent, so as to realize the extraction of the boron or lithium single product in the brine. The fixed bed is filled with boron adsorbent and lithium adsorbent, and the boron lithium adsorbent can be filled in a mixed mode (figure 1d) or in a layered mode (figure 1c), so that the boron lithium co-extraction in the brine is realized.
The traditional process for extracting boron and lithium from brine by fixed bed cyclic adsorption and desorption is shown in figure 2, a fixed bed filled with an adsorbent is adopted, and the operation process is divided into four steps as follows:
(1) b, adsorbing lithium: and (3) inputting the brine containing boron and lithium into a fixed bed filled with an adsorbent, adsorbing the boron and lithium in the brine by the adsorbent filled in the tower, and discharging the poor brine to a salt field.
(2) Primary water washing: stopping feeding brine, and then feeding a small amount of water to wash potassium, sodium, calcium, magnesium and other ions and impurities remained in the fixed bed, so as to reduce the content of impurity ions in the desorption solution. The dosage of the washing water is controlled, the adsorbed boron and lithium are prevented from losing along with the washing water, and the recovery rate of the boron and lithium is reduced;
(3) acid hydrolysis of boron-absorbing lithium: inputting dilute hydrochloric acid, eluting boron and lithium elements adsorbed in the fixed bed, desorbing the boron and lithium to obtain a high-grade boron and lithium solution, wherein the content of potassium, sodium, calcium, magnesium and other ions is low, and obtaining boric acid and lithium carbonate products after post-treatment;
(4) and (3) secondary water washing: after acid desorption, dilute hydrochloric acid retained in the fixed bed is washed by water, and dilute acid is recovered, so that pollution is reduced.
After the secondary water washing, the brine containing boron and lithium is input into the fixed bed again to adsorb the boron and lithium, and then the processes of adsorption, primary water washing, acid desorption and secondary water washing are formed to cyclically extract the boron and lithium in the brine. Because the traditional fixed bed adsorption elution cycle process belongs to intermittent operation, the problems of small brine treatment capacity, large diluted acid consumption and large water consumption exist, the cost and the energy consumption are high, the pollution is serious, and the large-scale production is not formed at present.
The process for extracting the boron and the lithium in the brine by the gradient simulated moving bed adsorption method comprises the following steps:
the invention adopts a novel pH gradient simulated moving bed adsorption method to jointly extract the boron and the lithium in the brine on a large scale, reduces energy consumption and cost and promotes the industrialization process.
Figure 3 shows a process for extracting boron and lithium from brine by constructing a pH gradient simulated moving bed from a plurality of fixed beds (in the case of 12 fixed bed operation), four input lines and four output lines dividing the 12 fixed beds into four zones, each zone containing 3 fixed beds connected in series.
Zone I: in the acid desorption area, eluting the boron and lithium elements adsorbed in the fixed bed by using dilute acid to obtain a high-grade boron and lithium solution;
zone II: a primary water washing area, wherein potassium, sodium, calcium, magnesium and other ions and impurities remained in the fixed bed are washed by a small amount of water;
zone III: in the adsorption zone, the brine containing boron and lithium is input into a fixed bed filled with an adsorbent, the boron and lithium in the brine are adsorbed and extracted by the adsorbent in the tower, and the poor brine is discharged to a salt field;
zone IV: in the secondary water washing area, the dilute hydrochloric acid retained in the washing tower is washed, and the waste acid liquid is recovered, so that the environmental pollution is reduced.
During the operation of the simulated moving bed, the adsorbent in the tower does not flow. The process is characterized in that a fixed bed is sequentially switched along the fluid flow direction through the material positions of an inlet and an outlet, so that countercurrent flow is formed between an adsorbent fixed phase and a fluid flowing phase, and the heat transfer rate and the mass transfer rate between the two phases are improved. As shown in fig. 3a and 3b, after adsorbing boron and lithium in brine by the adsorbent in zone III, the adsorbent is switched by a valve and then moved to zone II for water washing to remove other ions (such as magnesium, calcium, sodium and potassium ions) retained in the column. And then, the boron lithium solution is switched by a valve and then is moved to the area I for acid hydrolysis and adsorption of the boron lithium on the adsorbent, and a high-quality boron lithium solution is obtained through an extraction port. The desorbed adsorption tower moves to the region IV through valve switching to carry out secondary water washing, and dilute acid liquid retained in the desorption tower is recovered, so that the environmental pollution is reduced. And the fixed bed of the secondary water washing is moved to an adsorption zone III through valve switching, and the boron and the lithium in the brine are continuously adsorbed and recovered, and are continuously and circularly operated in sequence. If the system contains 12 fixed beds, the input and output ports move one fixed bed at a time by switching, and the switching 12 times is a cycle operation. After 20 cycles, the system can reach a stable operation state, and brine boron and lithium co-extraction is realized.
When all of the 12 fixed beds are filled with an adsorbent such as a manganese-based lithium ion sieve type, a titanium-based lithium ion sieve or a boron chelate resin, a single product (lithium or boron) is extracted from the salt lake brine after the simulated moving bed operation. When one fixed bed is filled with a lithium ion sieve and the other fixed bed is filled with boron chelating resin and is alternately arranged in the simulated moving bed system, the co-extraction of boron and lithium in salt lake brine can be realized. The lithium ion sieve and the boron chelating resin can be mixed and filled in each fixed bed, and the co-extraction of the boron and the lithium in the salt lake brine can also be realized, as shown in the fixed bed filling mode in figure 1.
The method for continuously extracting the boron and the lithium in the brine by the simulated moving bed adsorption separation method overcomes the defects of the traditional technology for extracting the boron or the lithium in the brine in the salt lake by the cyclic adsorption desorption of the fixed bed, and has the following advantages:
(1) the traditional fixed bed circulating adsorption and desorption process and the novel simulated moving bed adsorption and separation process both comprise four key steps; adsorption, primary water washing, acid desorption and secondary water washing. In the conventional fixed bed circulation process, only one fixed bed is used. The simulated moving bed is divided into four operation zones, including adsorption, primary water washing, acid desorption and secondary water washing, and each zone comprises a plurality of fixed beds which are connected in series for operation.
(2) Each zone of the simulated moving bed comprises a plurality of fixed beds which are connected in series for operation, and during the process of adsorbing boron and lithium in brine by the adsorbent, the input brine sequentially flows through each fixed bed in the adsorption zone. Every time the valve is switched, the input and output port only moves one fixed bed, the fixed bed enters the water washing area II, other fixed beds continuously adsorb the boron and lithium in the brine, the utilization rate of the adsorbent in the fixed bed is high, and the extraction efficiency of the boron and lithium in the brine is improved.
(3) The desorption zone of the simulated moving bed is also operated with a plurality of fixed beds in series. During desorption of the adsorbent, the incoming dilute hydrochloric acid desorbent will flow sequentially through each fixed bed in the desorption zone. And when the valve is switched every time, the input and output port only moves one fixed bed, the fixed bed enters the water washing zone IV, other fixed beds continue to desorb, the boron and lithium desorption efficiency is high, and the consumption of dilute hydrochloric acid is obviously reduced.
(4) In the cycle process of extracting boron and lithium in brine by an adsorption method, a large amount of fresh water is consumed by twice water washing, and the key is to save the consumption of the fresh water. Each zone of the simulated moving bed comprises a plurality of fixed beds which are connected in series, and input washing water flows through each fixed bed in sequence, which is equivalent to multiple uses, so that the use amount of the washing water can be remarkably reduced.
(5) The traditional fixed bed cyclic adsorption and desorption operation mode is an intermittent mode, the brine treatment capacity is small, and the boron and lithium yield is low. The simulated moving bed is a multi-tower series operation mode and is suitable for large-scale continuous production.
(6) In the traditional fixed bed circulating adsorption and desorption process, the adsorbent and the liquid cannot form countercurrent flow, and the extraction efficiency of boron or lithium is low. In the simulated moving bed adsorption separation process, the adsorbent in the tower and a liquid mobile phase can form countercurrent flow by frequently switching the input and output ports, so that the heat transfer and mass transfer rates are improved, and the boron and lithium extraction efficiency is improved;
(7) according to the condition that the brine contains boron and lithium, single boron or lithium extraction and boron and lithium co-extraction can be determined by selecting a fixed bed adsorbent filling mode. If all the fixed beds are filled with boron chelating resin, the simulated moving bed process extracts boron in the brine; if all the fixed beds are filled with lithium ion sieves, the simulated moving bed process extracts lithium in the brine; if all the fixed beds are mixed and filled with the lithium ion sieve and the boron chelating resin, the simulated moving bed process co-extracts boron and lithium in the brine.
Drawings
FIGS. 1 a-1 d show the manner of filling the boron lithium adsorbent in the fixed bed.
FIG. 2 is a traditional fixed bed cycle adsorption and desorption process for extracting boron and lithium from salt lake brine.
Fig. 3a is a schematic diagram of a four-zone open-circuit pH gradient simulated moving bed process for extracting boron and lithium from brine, when T is 0.
Fig. 3b is a schematic diagram of a four-zone open-circuit pH gradient simulated moving bed process for extracting boron and lithium from brine, when T is Ts.
Detailed Description
The following provides a specific embodiment of the pH gradient simulated moving bed process for combined extraction of boron and lithium from brines of the present invention on a laboratory scale, the fixed bed diameter and packing height are generally related to the brine throughput and the lithium recovery yield, and the examples are given only for the dimensions of the laboratory experiment. The experimental device, experimental conditions and experimental results can be amplified in an industrial scale.
Example 1 continuous extraction of boron from brine by gradient simulated moving bed Process
The brine comprises the following components: li+300mg/L,Na+1400mg/L,K+400mg/L,Ca2+30mg/L,Mg2+130g/L,B 300mg/L,Cl- 370g/L,pH 5.6
The fixed bed is filled with 12 boron adsorbents with the same size, the diameter of the tower is 25mm, the filling height of the adsorbents is 250mm, and the boron adsorbents are domestic D403 meglumine chelating resin.
The boron adsorption amount of the domestic D403 meglumine chelate resin can reach 10mg (B)/g (resin), the 0.5mol/L HCl solution can desorb the boron adsorbed by the D403 meglumine chelate resin, and the boron desorption rate reaches over 90 percent at room temperature.
The process for extracting boron from the brine by adopting a four-zone open-circuit pH gradient simulated moving bed consisting of a fixed bed filled with 12 boron adsorbents shown in figure 3. The experimental conditions and procedures were as follows:
(1) valve switching initial (switching time is 0) operating condition:
a) the boron-containing brine is input from the area III (fixed bed 7) at the input flow rate of 30mL/min, and after boron in the brine is sequentially adsorbed by the fixed bed 8 and the fixed bed 9, the brine is discharged to a salt field. Controlling the boron content in the discharged brine, and improving the recovery rate of boron in the brine to be more than 80%;
b) the fixed bed adsorbing boron from the brine will move to zone II for water washing to remove impurity ions (including Li) retained in the fixed bed+,Na+,K+,Ca2+,Mg2+,Cl-) So as to reduce impurity ions in the subsequent desorption liquid and improve the recovery purity of boron. The flow rate of input water is 20mL/min, the input water is input from the fixed bed 4, and then the input water is washed by the fixed bed 5 and the fixed bed 6 and discharged to a salt pan;
c) the boron adsorption fixed bed after water washing carries out acid desorption in an entering area I, desorption liquid is 0.5MHCl, the input flow is 10mL/min, the desorption liquid is input from the fixed bed 1, is discharged after passing through the fixed bed 2 and the fixed bed 3, the discharged liquid is recycled, high-purity boron solution is obtained, and Li in the solution+,Na+,K+,Ca2+,Mg2+The impurity content is low, and the total average value is less than 500 mg/L;
d) after the boron adsorbed in the fixed bed is desorbed, some dilute hydrochloric acid is retained in the bed and cannot be directly discharged to a salt pan, so that the environmental pollution is caused. Therefore, the dilute acid retained in the recovery tower is washed by water in the addition zone IV, the input water flow is 20mL/min, the dilute acid is input from the fixed bed 10, passes through the fixed bed 11 and the fixed bed 12 and is then discharged, and the discharged dilute acid liquid is recovered and recycled.
(2) The input and output valves are synchronously switched once (the switching time Ts is 15 min):
after the valve switching time interval set by the operation of the simulated moving bed is 15min, the input and output material port synchronously moves a fixed bed along the fluid flow direction. After the valves are switched, one fixed bed in each zone is moved to another zone, and the other fixed beds are correspondingly moved to a position opposite to the direction of fluid flow so as to make the adsorbent fixed phase and the liquid flow phase form a counter-current flow, but the flow rate of the input liquid and the output liquid in each zone is unchanged. After the valves are switched, the simulated moving bed operates as follows:
a) a fixed bed 7 in the adsorption zone III is switched into a zone II, boron-containing brine is input from the zone III (a fixed bed 8), the input flow is 30mL/min, and after boron in the brine is sequentially adsorbed by a fixed bed 9 and a fixed bed 10, the brine is discharged into a salt field;
b) the fixed bed 4 in the primary water washing zone II is switched into the zone I, the flow rate of water input from the fixed bed 5 is 20mL/min, and then the water is washed by the fixed bed 6 and the fixed bed 7 and discharged to a salt pan;
c) the fixed bed 1 in the acid desorption zone III is switched into a zone IV, 0.5MHCl with the input flow of 10mL/min is input from the fixed bed 2, and the solution is discharged after passing through the fixed bed 3 and the fixed bed 4 to obtain a high-purity boron solution with less content of other impurities;
d) the fixed bed 10 in the secondary water washing area IV is switched to the area I, water is input from the fixed bed 11, the input flow is 20mL/min, the water is discharged after passing through the fixed bed 12 and the fixed bed 1, and the discharged dilute acid liquid is recycled.
(3) The valve is switched N times (switching time NTs is 30N min) for operation:
after the valve switching time interval set by the operation of the simulated moving bed is 15min, the input and output material port continues to synchronously move a fixed bed along the fluid flow direction. After the valves are switched, one fixed bed in each zone is moved to another zone, and the other fixed beds are correspondingly moved to a position opposite to the direction of fluid flow so as to make the adsorbent fixed phase and the liquid flow phase form a counter-current flow, but the flow rate of the input liquid and the output liquid in each zone is unchanged.
12 fixed beds filled with D403 meglumine chelating resin, each time the valve is switched, the input and output material ports synchronously move one fixed bed along the fluid flowing direction, so the valve is switched 12 times, and a cycle operation is completed. About 20 cycles, the system is able to achieve stable operation. After the operation is stable, the process can continuously adsorb and recover boron in the brine, the recovery rate reaches more than 80 percent, the desorption of the boron can also reach more than 80 percent by adopting 0.5MHCl, and the boron adsorption quantity of the D403 meglumine chelate resin reaches about 10mg (B)/g (resin). The boron solution obtained after extraction has low impurity ion content, and the boric acid is crystallized and separated out by adding hydrochloric acid after the boron-rich solution is concentrated.
Example 2 continuous extraction of lithium from brine by a gradient simulated moving bed Process
The original brine comprises the following components: li+300mg/L,Na+1400mg/L,K+400mg/L,Ca2+30mg/L,Mg2+130g/L,B 300mg/L,Cl-370g/L, pH 5.6. The ion sieve can release hydrogen ions when absorbing lithium ions in brine, so that the pH value of the brine is reduced, and the amount of the lithium ions absorbed by the ion sieve is influenced. Therefore, 0.05M NaHCO was added to the brine3To slow down the accumulation of displaced hydrogen ions in the brine.
The fixed bed is filled with 12 lithium adsorbents with the same size, the diameter of the tower is 25mm, the filling height of the adsorbents is 250mm, and the amount of lithium in the brine can reach 8mg (Li) by using a titanium lithium ion sieve adsorbent+) The solution of 0.5MHCl can desorb the lithium adsorbed by the ion sieve, and the desorption rate of the lithium reaches over 90 percent at room temperature.
The process for extracting lithium from brine by adopting a four-zone open-circuit pH gradient simulated moving bed consisting of a fixed bed filled with 12 ion sieves as shown in figure 3. The experimental conditions and procedures were as follows:
simulated moving bed cycling is the start of the experimental run:
(1) valve switching initial (switching time is 0) operating condition:
a) lithium-containing brine is fed from the zone III (fixed bed 7) at a flow rate of 30mL/min, and after lithium in the brine is sequentially adsorbed by the fixed bed 8 and the fixed bed 9, the brine is discharged to a salt field. The lithium content in the discharged brine is controlled, and the recovery rate of lithium in the brine is improved to be more than 80%;
b) the fixed bed adsorbing lithium from brine will move to zone II for water washing to remove impurity ions (including B, Na) retained in the fixed bed+,K+,Ca2+,Mg2+,Cl-) So as to reduce impurity ions in the subsequent desorption liquid and improve the recovery purity of lithium. The flow rate of input water is 20mL/min, the input water is input from the fixed bed 4, and then the input water is washed by the fixed bed 5 and the fixed bed 6 and discharged to a salt pan;
c) the washed lithium-adsorbing fixed bed enters a zone I for acid desorption, desorption liquid is 0.5MHCl, the input flow is 10mL/min, the desorption liquid is input from the fixed bed 1, is discharged after passing through the fixed bed 2 and the fixed bed 3, and the discharged liquid is recovered to obtain high-purity lithium solutionB, Na in solution+,K+,Ca2+,Mg2+The impurity content is low, and the total average value is less than 500 mg/L;
d) after the lithium adsorbed in the fixed bed is desorbed, some dilute hydrochloric acid is retained in the bed and cannot be directly discharged to a salt pan, so that the environmental pollution is caused. Therefore, the dilute acid retained in the recovery tower is washed by water in the addition zone IV, the input water flow is 20mL/min, the dilute acid is input from the fixed bed 10, passes through the fixed bed 11 and the fixed bed 12 and is then discharged, and the discharged dilute acid liquid is recovered and recycled.
(2) The input and output valves are synchronously switched once (the switching time Ts is 15 min):
after the valve switching time interval set by the operation of the simulated moving bed is 15min, the input and output material port synchronously moves a fixed bed along the fluid flow direction. After the valves are switched, one fixed bed in each zone is moved to another zone, and the other fixed beds are correspondingly moved to a position opposite to the direction of fluid flow so as to make the adsorbent fixed phase and the liquid flow phase form a counter-current flow, but the flow rate of the input liquid and the output liquid in each zone is unchanged. After the valves are switched, the simulated moving bed operates as follows:
a) the fixed bed 7 in the adsorption zone III is switched to the zone II, lithium-containing brine is input from the zone III (the fixed bed 8), the input flow is 30mL/min, lithium in the brine is sequentially adsorbed by the fixed bed 9 and the fixed bed 10, and then the brine is discharged to a salt field.
b) The fixed bed 4 in the primary water washing zone II is switched into the zone I, the flow rate of water input from the fixed bed 5 is 20mL/min, and then the water is washed by the fixed bed 6 and the fixed bed 7 and discharged to a salt pan;
c) the fixed bed 1 in the acid desorption zone III is switched into a zone IV, 0.5MHCl with the input flow of 10mL/min is input from the fixed bed 2, and the lithium solution is discharged after passing through the fixed bed 3 and the fixed bed 4 to obtain a high-purity lithium solution with less content of other impurities;
d) the fixed bed 10 in the secondary water washing area IV is switched to the area I, water is input from the fixed bed 11, the input flow is 20mL/min, the water is discharged after passing through the fixed bed 12 and the fixed bed 1, and the discharged dilute acid liquid is recycled.
(3) The valve is switched N times (switching time is NTs) for the operation:
after the valve switching time interval set by the operation of the simulated moving bed is 15min, the input and output material port continues to synchronously move a fixed bed along the fluid flow direction. After the valves are switched, one fixed bed in each zone is moved to another zone, and the other fixed beds are correspondingly moved to a position opposite to the direction of fluid flow so as to make the adsorbent fixed phase and the liquid flow phase form a counter-current flow, but the flow rate of the input liquid and the output liquid in each zone is unchanged.
The 12 fixed beds filled with the titanium-based lithium ion sieve adsorbent synchronously move one fixed bed along the fluid flowing direction at each valve switching time, so that the valves are switched 12 times to complete one cycle operation. About 20 cycles, the system is able to achieve stable operation. After the operation is stable, the process can continuously adsorb and recover lithium in the brine, the recovery rate reaches more than 80 percent, the desorption of the lithium can also reach more than 80 percent by adopting 0.5MHCl, and the lithium adsorption amount of the titanium lithium ion sieve reaches about 8mg (Li)+) (ii)/g (ion sieve). The lithium solution obtained after extraction has low impurity ion content, and after the lithium-rich solution is concentrated, sodium carbonate is added after neutralization to crystallize and separate out lithium carbonate.
Example 3 continuous extraction of lithium and boron from brine by a gradient simulated moving bed process
The original brine comprises the following components: li+300mg/L,Na+1400mg/L,K+400mg/L,Ca2+30mg/L,Mg2+130g/L,B 300mg/L,Cl-370g/L, pH 5.6. The ion sieve can release hydrogen ions when absorbing lithium ions in brine, so that the pH value of the brine is reduced, and the amount of the lithium ions absorbed by the ion sieve is influenced. Therefore, 0.05M NaHCO was added to the brine3To slow down the accumulation of displaced hydrogen ions in the brine.
12 fixed beds which are filled by mixing lithium adsorbent and boron adsorbent and have the same size, the diameter of the tower is 25mm, the total height of the mixed adsorbent is 250mm, the lithium adsorbent is filled at the bottom of the tower, the filling height is 125mm, the boron adsorbent is filled at the top of the tower, and the filling height is 125 mm. The titanium lithium ion sieve is a lithium adsorbent, and the amount of lithium in the absorbed brine can reach 8mg(Li+) The solution of 0.5MHCl can desorb the lithium adsorbed by the ion sieve, and the desorption rate of the lithium reaches over 90 percent at room temperature. The boron adsorbent is domestic D403 meglumine chelate resin, the amount of boron in the adsorbed brine reaches 10mg (B)/g (resin), the boron adsorbed by the D403 meglumine chelate resin can be desorbed by 0.5MHCl solution, and the boron desorption rate reaches over 90% at room temperature.
The process for extracting the boron and the lithium in the brine by adopting a four-zone open-circuit pH gradient simulated moving bed consisting of a fixed bed filled with 12 ion sieves shown in figure 3. The experimental conditions and procedures were as follows:
simulated moving bed cycling is the start of the experimental run:
(1) valve switching initial (switching time is 0) operating condition:
a) the boron-containing lithium brine is input from the area III (the fixed bed 7) at the flow rate of 15mL/min, and is discharged into a salt field after boron and lithium in the brine are sequentially adsorbed by the fixed bed 8 and the fixed bed 9. Controlling the content of boron and lithium in the discharged brine, and improving the recovery rate of the boron and the lithium in the brine to be more than 80%;
b) the fixed bed adsorbing boron and lithium from the brine moves to the zone II for water washing to remove impurity ions (including Na) retained in the fixed bed+,K+,Ca2+,Mg2+) So as to reduce impurity ions in the subsequent desorption liquid and improve the recovery purity of the boron and the lithium. The flow rate of input water is 20mL/min, the input water is input from the fixed bed 4, and then the input water is washed by the fixed bed 5 and the fixed bed 6 and discharged to a salt pan;
c) the washed fixed bed for adsorbing boron and lithium enters a zone I to be subjected to acid desorption, desorption liquid is 0.5MHCl, the input flow is 10mL/min, the desorption liquid is input from the fixed bed 1, is discharged after passing through the fixed bed 2 and the fixed bed 3, the discharged liquid is recycled, high-purity boron and lithium solution is obtained, and Na in the solution+,K+,Ca2+,Mg2+The impurity content is low, and the total average value is less than 500 mg/L;
d) after the boron and lithium adsorbed in the fixed bed are desorbed, some dilute hydrochloric acid is retained in the bed and cannot be directly discharged to a salt pan, so that the environmental pollution is caused. Therefore, the dilute acid retained in the recovery tower is washed by water in the addition zone IV, the input water flow is 20mL/min, the dilute acid is input from the fixed bed 10, passes through the fixed bed 11 and the fixed bed 12 and is then discharged, and the discharged dilute acid liquid is recovered and recycled.
(2) The input and output valves are synchronously switched once (the switching time Ts is 15 min):
after the valve switching time interval set by the operation of the simulated moving bed is 15min, the input and output material port synchronously moves a fixed bed along the fluid flow direction. After the valves are switched, one fixed bed in each zone is moved to another zone, and the other fixed beds are correspondingly moved to a position opposite to the direction of fluid flow so as to make the adsorbent fixed phase and the liquid flow phase form a counter-current flow, but the flow rate of the input liquid and the output liquid in each zone is unchanged. After the valves are switched, the simulated moving bed operates as follows:
a) and a fixed bed 7 in the adsorption zone III is switched to a zone II, the boron-containing lithium brine is input from the zone III (a fixed bed 8), the input flow is 15mL/min, lithium in the brine is sequentially adsorbed by a fixed bed 9 and a fixed bed 10, and then the brine is discharged to a salt field.
b) The fixed bed 4 in the primary water washing zone II is switched into the zone I, the flow rate of water input from the fixed bed 5 is 20mL/min, and then the water is washed by the fixed bed 6 and the fixed bed 7 and discharged to a salt pan;
c) the fixed bed 1 in the acid desorption zone III is switched into a zone IV, 0.5MHCl with the input flow of 10mL/min is input from the fixed bed 2, and the solution is discharged after passing through the fixed bed 3 and the fixed bed 4 to obtain a high-purity boron-lithium solution with less content of other impurities;
d) the fixed bed 10 in the secondary water washing area IV is switched to the area I, water is input from the fixed bed 11, the input flow is 20mL/min, the water is discharged after passing through the fixed bed 12 and the fixed bed 1, and the discharged dilute acid liquid is recycled.
(3) The valve is switched N times (switching time is NTs) for the operation:
after the valve switching time interval set by the operation of the simulated moving bed is 15min, the input and output material port continues to synchronously move a fixed bed along the fluid flow direction. After the valves are switched, one fixed bed in each zone is moved to another zone, and the other fixed beds are correspondingly moved to a position opposite to the direction of fluid flow so as to make the adsorbent fixed phase and the liquid flow phase form a counter-current flow, but the flow rate of the input liquid and the output liquid in each zone is unchanged.
The 12 boron lithium adsorbent filled fixed beds, each time the valve is switched, the input and output material ports synchronously move one fixed bed along the fluid flowing direction, so the valve is switched for 12 times, and one cycle operation is completed. About 20 cycles, the system is able to achieve stable operation. After the operation is stable, the process can continuously adsorb and recover the boron and the lithium in the brine, the recovery rate reaches more than 80 percent, the desorption of the boron and the lithium can also reach more than 80 percent by adopting 0.5MHCl, and the lithium adsorption amount of the titanium lithium ion sieve reaches about 8mg (Li)+) The boron content in the D403 meglumine chelate resin absorbed brine reaches 10mg (B)/g (resin). The extracted boron-lithium solution has low impurity ion content, the boron-lithium-rich solution is concentrated, then hydrochloric acid is added for crystallization to separate out boric acid, and then sodium carbonate is added for crystallization to separate out lithium carbonate after neutralization.
The invention provides a gradient simulated moving bed adsorption method for combined extraction of boron and lithium in brine, and the key technology for extracting boron and lithium in brine by the adsorption method comprises two parts, namely research and development of a high-efficiency boron and lithium adsorbent and development of a low-energy-consumption adsorption process.
Low-grade boron-lithium brine enters from the area III, and after the boron-lithium is adsorbed by the fixed bed adsorbent, the lean brine is discharged into a salt pan; after the valve is switched, the fixed bed is moved to a zone II for primary water washing to remove other impurity ions remained in the bed; after switching through a valve, moving the fixed bed to the region I for acidolysis and adsorption of the boron and lithium on the adsorbent, and obtaining a high-quality boron and lithium solution from an extraction port; the desorbed fixed bed is switched by a valve and moves to a region IV for secondary water washing; then the mixture is switched by a valve to move to an adsorption area III, and continuous cycle operation is carried out in sequence. At certain time intervals, the input and output material ports synchronously move a fixed bed along the flowing direction of the fluid, the valves are switched circularly, the fixed bed circularly operates from the zone III → the zone II → the zone I → the zone IV → the zone III … … in sequence, the co-extraction of the boron and the lithium in the brine is realized, and the high-quality boron and the lithium solution can be continuously obtained at the extraction port. The invention reduces the extraction cost and energy consumption of boron or lithium.

Claims (10)

1. A gradient simulated moving bed method for large-scale combined extraction of boron and lithium in brine is characterized in that: a plurality of fixed bed systems are adopted; each fixed bed is filled with an adsorbent; the four material input ports and the four material output ports divide the fixed bed system into four areas, each area comprises at least one fixed bed which is operated in series, open circuits are formed among the areas, and the whole system is in a four-area open circuit state;
zone I: in the acid desorption area, eluting the boron and lithium elements adsorbed by the adsorbent in the fixed bed by using dilute acid to obtain a high-grade boron and lithium solution;
zone II: a primary water washing zone for washing the ions and impurities remaining in the fixed bed with a small amount of water;
zone III: in the adsorption zone, the brine containing boron and lithium is input into a fixed bed filled with an adsorbent, and the boron and lithium in the brine are adsorbed and extracted by the adsorbent in the tower;
zone IV: a secondary water washing area, which uses a small amount of water to wash the remained dilute hydrochloric acid in the tower;
after a certain time interval, the input and output material port synchronously moves a fixed bed along the fluid flowing direction; after the valves are switched, one fixed bed in each zone moves to the other zone, and other fixed beds correspondingly move to a position in a direction opposite to the fluid flowing direction, so that countercurrent flow is formed between the adsorbent fixed phase and the fluid flowing phase;
the method comprises the following steps:
(1) the low-grade boron-lithium brine enters the zone III and flows through each fixed bed of the zone III in sequence;
(2) after boron and lithium in brine are extracted by an adsorbent in a fixed bed, the brine is shifted to a zone II for primary water washing after being switched by a valve, and other ions retained in a tower are removed;
(3) after impurity ions retained in the fixed bed are washed out, the impurities are switched by a valve and then are moved to a region I for acid hydrolysis and adsorption of boron and lithium on the adsorbent, and a high-quality boron and lithium solution is obtained from an extraction port;
(4) the fixed bed after being desorbed by dilute acid is switched to move to a region IV through a valve for secondary water washing, and dilute acid liquid retained in the desorption tower is recovered;
(5) and the fixed bed of the secondary water washing is moved to an adsorption zone III through valve switching, and the boron and the lithium in the brine are continuously adsorbed and recovered, and are continuously and circularly operated in sequence.
2. The gradient simulated moving bed process for large-scale combined extraction of boron and lithium from brine according to claim 1, wherein: each zone contains at least one fixed bed; the number of fixed beds is at least 4.
3. The gradient simulated moving bed process for large-scale combined extraction of boron and lithium from brine according to claim 1, wherein: the adsorbent is selected from one or two of boron adsorbent and lithium adsorbent; the adsorbent is filled in a fixed bed, and a single adsorbent is filled in the fixed bed; and filling the boron adsorbent and the lithium adsorbent in the fixed bed, wherein the filling comprises mixed filling and layered filling.
4. The gradient simulated moving bed process for large-scale combined extraction of boron and lithium from brine according to claim 1, wherein: the boron adsorbent is meglumine chelating resin.
5. The gradient simulated moving bed process for large-scale combined extraction of boron and lithium from brine according to claim 1, wherein: the lithium adsorbent is a titanium-based lithium ion sieve or a manganese-based lithium ion sieve.
6. The gradient simulated moving bed process for large-scale combined extraction of boron and lithium from brine according to claim 1, wherein: the low-grade boron-lithium brine comprises the following components in percentage by weight: the lithium content is 50 mg/L-300 mg/L, and the boron content is 50 mg/L-300 mg/L.
7. The gradient simulated moving bed process for large-scale combined extraction of boron and lithium from brine according to claim 1, wherein: in the step (1), after the low-grade boron-lithium brine enters the adsorption area, the brine input amount is adjusted, the brine temperature is 10-40 ℃, and the recovery rate of boron and lithium in the brine is controlled to be more than 70%.
8. The gradient simulated moving bed process for large-scale combined extraction of boron and lithium from brine according to claim 1, wherein: in the step (2), the flow rate of the input water is adjusted, the water temperature is 10-40 ℃, and the impurity ion elution rate in the brine retained in the adsorption tower is over 90 percent.
9. The gradient simulated moving bed process for large-scale combined extraction of boron and lithium from brine according to claim 1, wherein: in the step (3), the desorbent is dilute hydrochloric acid solution, the concentration range is 0.2mol/L HCl-0.5 mol/L HCl, the temperature is 10-40 ℃, and the input dilute hydrochloric acid flow is adjusted, so that the desorption rate of boron and lithium is over 80 percent.
10. The gradient simulated moving bed process for large-scale combined extraction of boron and lithium from brine according to claim 1, wherein: in the step (4), the secondary washing is carried out, the water temperature is 10-40 ℃, the dilute hydrochloric acid retained in the washing tower is used for controlling the pH value of the effluent liquid to be 3-7.
CN202110268267.9A 2021-03-12 2021-03-12 Gradient simulated moving bed method for large-scale combined extraction of boron and lithium in brine Pending CN113088695A (en)

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