CN111533147B - Method for improving crystallization efficiency of lithium carbonate in solar cell - Google Patents
Method for improving crystallization efficiency of lithium carbonate in solar cell Download PDFInfo
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- CN111533147B CN111533147B CN202010449112.0A CN202010449112A CN111533147B CN 111533147 B CN111533147 B CN 111533147B CN 202010449112 A CN202010449112 A CN 202010449112A CN 111533147 B CN111533147 B CN 111533147B
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Abstract
The invention relates to a method for improving crystallization efficiency of lithium carbonate in a solar cell, belongs to the technical field of lithium extraction in carbonate type salt lakes, and solves the problem of low crystallization efficiency of lithium carbonate in solar cellsThe existing carbonate type salt lake high Li+Low CO3 2‑The problem of low lithium yield of the traditional solar cell lithium precipitation method by using halogen as a raw material. The method for improving the crystallization efficiency of lithium carbonate in the solar cell comprises the following steps: step 1: carbonate type salt lake high Li+Low CO3 2‑Preparing a salt gradient solar pond by taking halogen-forming raw materials; step 2: repeatedly performing mechanical disturbance and forced convection circulation operation on a lithium precipitation layer at the bottom of the salt gradient solar cell for many times; and step 3: and (4) after lithium carbonate in the lithium precipitation layer at the bottom of the solar cell is completely precipitated, performing halogen discharge operation, and collecting the lithium carbonate mixed salt. The method is based on the collision nucleation principle, and greatly increases Li in the brine through mechanical disturbance and enhanced circulation of the lithium precipitation layer+And CO3 2‑The collision combines the opportunity, makes the temperature field and the concentration field distribution of analyzing lithium layer brine more even, accelerates lithium carbonate crystallization and precipitation, improves the solar pond lithium yield by a wide margin.
Description
Technical Field
The invention relates to the technical field of lithium extraction in carbonate type salt lakes, in particular to a method for improving crystallization efficiency of lithium carbonate in a solar pond.
Background
The Tibet region of China has a unique carbonate type lithium-rich salt lake, such as Zabuye, Dang xiong stagger, Jie Chaka and the like, the lithium resource is very rich, the ratio of magnesium to lithium in brine is very low, and compared with sulfate type brine with high magnesium-lithium ratio, the lithium separation and extraction are easier. For carbonate brine, lithium is continuously enriched in the brine concentration process, is easy to disperse and deposit along with minerals such as alkalis in the form of lithium carbonate, is difficult to concentrate and separate out, and is not beneficial to collection.
Since 2004, the traditional solar cell temperature-rising lithium-separating method is always applied to the industrial production of Tibet Zaubeya salt lake lithium carbonate. However, from the actual production situation, the annual output of zabuje stays below 4000 tons of industrial-grade lithium carbonate for many years, and the production expansion are difficult to achieve, on one hand, because the spatial distribution field of the temperature and the concentration of the lithium-rich brine of the lithium precipitation layer (lower convection layer) of the traditional solar pond is not uniform, the periphery and the bottom are lower, the middle is higher, the crystallization precipitation of lithium carbonate is incomplete, and in addition, the temperature rise amplitude of the solar pond is not high enough, the crystallization period is too long, so that the total precipitation rate of lithium carbonate is lower, and the lithium precipitation effect is not good; on the other hand, since the lithium-rich brine poured into the solar pond is bittern in winter, although Li is present+Higher concentration, but CO3 2-Lower concentration of Li+Incomplete precipitation also results in low overall precipitation rate of lithium carbonate and poor lithium precipitation effect, the grade of lithium carbonate in the produced lithium concentrate is low, and lithium loss in tail halide discharged after lithium precipitation is serious.
Therefore, it is urgently needed to provide a method for improving the crystallization efficiency of lithium carbonate in the solar cell.
Disclosure of Invention
In view of the above analysis, the present invention aims to provide a method for improving the crystallization efficiency of lithium carbonate in a solar cell, so as to solve the problems of low crystallization efficiency and low yield of lithium carbonate in the existing solar cell.
The purpose of the invention is mainly realized by the following technical scheme:
a method for improving crystallization efficiency of lithium carbonate in a solar cell comprises the following steps:
step 1: carbonate type salt lake high Li+Low CO3 2-Preparing a salt gradient solar pond by taking halogen-forming raw materials;
step 2: repeatedly performing mechanical disturbance and forced convection circulation operation on a lithium precipitation layer at the bottom of the salt gradient solar cell for many times;
and step 3: and (4) after lithium carbonate in the lithium precipitation layer at the bottom of the solar cell is completely precipitated, performing halogen discharge operation, and collecting the lithium carbonate mixed salt.
Further, in the step 2, a brine mixing device is adopted to perform repeated mechanical disturbance and forced convection circulation operation on the lithium-rich brine in the lithium precipitation layer at the bottom of the salt gradient solar pond.
Furthermore, the brine mixing equipment is one or the combination of water pumping and injecting equipment and stirring equipment.
Further, before step 1, a stirring device is arranged at the bottom and/or the side slope of the solar pond.
Furthermore, the number of the stirring devices is multiple, and the vertical placement positions of the multiple stirring devices are not on the same horizontal plane.
Further, the water pumping and injecting device is a submersible pump.
Furthermore, a water outlet of the submersible pump is led out to the bank along the side slope through a water pipe, is inserted into the other end of the pool bottom after being surrounded along the edge of the pool body, the submersible pump is started and the flow of the submersible pump is controlled, and the circulating brine pumping and filling operation is continuously carried out in a lithium precipitation layer.
Furthermore, the flow range of the submersible pump is 30-100 m3/h。
Furthermore, the number of the submersible pumps is multiple, and the vertical placement positions of the submersible pumps are not on the same horizontal plane.
Further, the number of the submersible pumps is 200-2000 m per average2A submersible pump is placed.
Furthermore, the horizontal placing positions of the multiple submersible pumps are placed diagonally or equidistantly.
Furthermore, the vertical placement positions of the multiple submersible pumps are located in the range from the bottom of the solar pond to the position 3/10 below the surface of the lithium precipitation layer and with the thickness of the lithium precipitation layer.
Further, in the step 2, the number of mechanical disturbance is 1-10, and the time length of a single time is 1-120 h.
Further, in step 3, the basis for judging that lithium carbonate is completely precipitated is as follows: monitoring Li of brine in solar pond lithium precipitation layer+Concentration of when Li+The precipitation of lithium carbonate was considered complete when the concentration dropped below 1.0 g/L.
Further, high Li+Low CO3 2-In halogen formation Li+The concentration is more than 1.5 g/L.
Further, step 1 comprises the steps of:
adding high Li into carbonate type salt lake+Low CO3 2-The formed brine is subjected to solarization, evaporation and concentration to form lithium-rich formed brine, and the lithium-rich formed brine is filled into the bottom of the solar pond;
laying a fresh water layer on the lithium-rich bittern-forming surface layer;
standing, and after the salt gradient solar cell is completely formed and enters a stable temperature rise lithium precipitation stage, utilizing a water pump to pump Na2CO3The saturated solution is injected into the bottom of the solar pond and Na is added2CO3Mixing saturated solution and lithium-rich bittern to obtain Na as bottom2CO3The salt gradient solar cell comprises a saturated solution and a lithium-rich halogen-forming mixed solution.
Furthermore, the injection speed of the water pump is 30-100 m3/h。
Further, step 1 comprises the steps of:
adding high Li into carbonate type salt lake+Low CO3 2-The formed halogen is evaporated and concentrated by solarization to form lithium-rich formed halogen;
mixing Na2CO3Adding the saturated solution into lithium-rich bittern, mixing, and adding Na2CO3Injecting the saturated solution and the lithium-rich halogen-forming mixed solution into the bottom of the solar cell;
in Na2CO3Laying a fresh water layer on the surface layer of the saturated solution and the mixed solution rich in lithium and halogen;
standing, and obtaining Na at the bottom after the salt gradient solar cell is completely formed and enters a stable temperature rise lithium precipitation stage2CO3The salt gradient solar cell comprises a saturated solution and a lithium-rich halogen-forming mixed solution.
Further, Na2CO3The volume ratio of the saturated solution to the lithium-rich halogen is 1:30-1: 8.
Further, step 1 is preceded by the following steps: preparation of Na2CO3And (4) saturated solution.
Further, Na is prepared by adopting a stirring tank2CO3The stirring tank is provided with a heater, the heater is connected with solar power supply equipment, and the solar power supply equipment is used for supplying power to the heater.
Compared with the prior art, the invention has at least one of the following beneficial effects:
a) the method for improving the crystallization efficiency of lithium carbonate in the solar cell provided by the invention uses carbonate type salt lake high Li+Low CO3 2-The brine forming is used as a raw material, on the basis of temperature rise and lithium precipitation of a traditional solar pond and based on a collision nucleation principle, the crystallization efficiency of lithium carbonate is improved by a mechanical disturbance and enhanced circulation method, on the premise that a middle transition layer of the solar pond is not damaged, mechanical disturbance and forced convection circulation are carried out on brine of a lithium precipitation layer at the bottom by brine mixing equipment, and Li in the brine is greatly increased+And CO3 2-The collision combination opportunity promotes the distribution of the temperature field and the concentration field of brine of the lithium separation layer of the solar cell to be more uniform, and accelerates the crystallization separation of lithium carbonate in the solar cell, thereby greatly improving the lithium yield of the solar cell.
b) The method for improving the crystallization efficiency of lithium carbonate in the solar cell adopts a carbonate precipitation method and adopts high Li filled into the solar cell+Low CO3 2-Adding CO artificially into bittern3 2-Simultaneously adopts brine mixing equipment to mix Na2CO3The saturated solution and the brine of the solar cell lithium separation layer are fully and uniformly mixed to promote the brine of the solar cell lithium separation layerThe temperature field and the concentration field of the water are distributed more uniformly, so that Li in the halogen+More with Li2CO3The form is crystallized and separated out, and then the solar pond separates out Li in the brine of the lithium layer+The precipitation is more complete, thereby greatly improving the yield of the lithium carbonate.
c) The method for improving the crystallization efficiency of the lithium carbonate in the solar cell, provided by the invention, has the advantages of simple steps, easiness in operation, remarkable effect, economy, environmental friendliness, no environmental pollution and wide application prospect.
In the invention, the technical schemes can be combined with each other to realize more preferable combination schemes. Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and drawings.
Drawings
The drawings are only for purposes of illustrating particular embodiments and are not to be construed as limiting the invention, wherein like reference numerals are used to designate like parts throughout.
FIG. 1 is a schematic flow chart of a method for improving the crystallization efficiency of lithium carbonate in a solar cell according to an embodiment of the present invention;
FIG. 2 is a schematic diagram illustrating a process of injecting an alkali solution into a lithium deposition layer of a solar cell according to an embodiment of the present invention;
FIG. 3 is a schematic view of the process of mixing alkali solution and rich lithium into brine and filling the mixture into a solar pond according to the embodiment of the present invention;
fig. 4 is a schematic diagram of the arrangement of a submersible pump in a solar pond in the embodiment of the invention.
Reference numerals:
1-a solar pond main body; 2-a fresh water layer; 3-a transition layer; 4-a lithium-separating layer; 5-a submersible pump; 6-a stirring tank; 7-a brine conveying channel; 8-a water pipe; 9-water outlet of the water pipe.
Detailed Description
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate preferred embodiments of the invention and together with the description, serve to explain the principles of the invention and not to limit the scope of the invention.
The invention discloses a method for improving crystallization efficiency of lithium carbonate in a solar cell, which adopts carbonate type salt lake with high Li + low CO3 2-The brine is used as a raw material, on the basis of temperature rise and lithium precipitation of a traditional solar pond and based on the collision nucleation principle, under the premise that a middle transition layer of the solar pond is not damaged, mechanical disturbance and forced convection circulation are carried out on the brine of the lithium precipitation layer at the bottom, and Li in the brine is greatly increased+And CO3 2-The collision combines the chance, promotes the temperature field and the concentration field distribution of the solar pond lithium analysis layer brine to be more even, accelerates the crystallization and the separation of lithium carbonate in the solar pond, thereby greatly improving the crystallization efficiency of the lithium carbonate in the solar pond and further improving the lithium yield of the solar pond.
As shown in fig. 2 to 4, the solar pond includes a solar pond body 1, the solar pond body 1 includes a pond bottom, a side slope and a pond bank, the salt gradient solar pond obtained by pouring the lithium-rich brine into the solar pond is paved with a layer of fresh water on the surface layer, and a lithium precipitation layer 4, a transition layer 3 and a fresh water layer 2 are sequentially arranged from bottom to top on the longitudinal structure.
An operation flow chart of the method for improving the crystallization efficiency of lithium carbonate in the solar cell is shown in fig. 1, and the method comprises the following steps:
step 1: carbonate type salt lake high Li+Low CO3 2-The salt gradient solar pond is manufactured by taking halogen as a raw material.
Step 2: and (3) carrying out repeated mechanical disturbance and forced convection circulation operation on the lithium-rich halogen in the lithium precipitation layer 4 at the bottom of the salt gradient solar pond by adopting brine mixing equipment. On the premise of ensuring that the transition layer 3 in the middle of the solar pond is not damaged, brine mixing equipment is adopted to carry out mechanical disturbance and forced convection circulation on the lithium-rich brine of the solar pond lithium precipitation layer 4, and the lithium precipitation layer 4 is called as a lower convection layer.
And step 3: and (4) after lithium carbonate in the lithium precipitation layer 4 at the bottom of the solar cell is completely precipitated, performing halogen discharge operation, and collecting the lithium carbonate mixed salt.
The reaction formula of the solar cell lithium separation process is as follows: 2Li++CO3 2-→Li2CO3↓, CO in the solar cell lithium-separating layer3 2-The concentration of (a) will directly affect the reaction rate and the amount of lithium carbonate produced. The method of this example uses carbonate type salt lake high Li+Low CO3 2-The bittern is used as raw material, on the basis of traditional solar cell temp. -rising lithium precipitation, a carbonate precipitation method is adopted, and CO is artificially added into the lithium-enriched bittern filled into solar cell3 2-Promote chemical equilibrium of 2Li++CO3 2-→Li2CO3↓ moves rightwards to form Li in halogen+More with Li2CO3The form is crystallized and separated out, so that the solar pond lithium separation layer 4 contains Li in brine+The precipitation is more complete, thereby greatly improving the yield of the lithium carbonate.
In step 1, Na is injected into the bottom of the solar cell2CO3Saturated solution to obtain Na at the bottom2CO3The salt gradient solar cell comprises a saturated solution and a lithium-rich halogen-forming mixed solution. Adding Na to the bottom of the solar pond2CO3Saturated solution to obtain Na at the bottom2CO3The salt gradient solar cell of the saturated solution and the lithium-rich halogen-forming mixed solution comprises the following two modes, wherein the two modes are different in alkali adding mode, and specifically comprise the following steps:
in the first mode, carbonate type salt lake high Li+Low CO3 2-The formed halogen is concentrated by solarization and evaporation to form lithium-rich formed halogen, wherein the lithium-rich formed halogen is high Li+Low CO3 2-Halogen-forming, Li+When the concentration is more than 1.5g/L, filling the lithium-rich halogen into the bottom of the solar pond; laying a fresh water layer 2 on the lithium-rich halogen-forming surface layer; standing for several days until the salt gradient solar pond is completely formed and enters a stable temperature rise lithium precipitation stage, and then pumping Na by using a water pump2CO3The saturated solution is injected into the bottom of the solar pond to make Na2CO3Mixing the saturated solution with lithium-rich halogen to obtain Na at the bottom2CO3The salt gradient solar cell comprises a saturated solution and a lithium-rich halogen-forming mixed solution.
Wherein Na is added2CO3The time of saturated solution depends on the solar cell lithium deposition layer4, the temperature of the brine is determined, and the alkali adding operation is carried out after the temperature of the brine is raised to be more than 25 ℃ and basically kept stable. Na is pumped by a water pump2CO3The saturated solution is slowly injected into the lithium precipitation layer 4 at the bottom of the solar pond through a pipeline at a certain injection speed, the injection process is as shown in figure 2, and the injection flow rate of a water pump is controlled to be 30-100 m3The flow rate parameter can effectively avoid disturbance and damage of the transition layer 3 (salt gradient layer) of the solar cell.
In the second mode, the carbonate type salt lake is high in Li+Low CO3 2-The formed halogen is concentrated by solarization and evaporation to form lithium-rich formed halogen, wherein the lithium-rich formed halogen is high Li+Low CO3 2-Halogen-forming, Li+The concentration is more than 1.5 g/L; mixing Na2CO3Adding the saturated solution into lithium-rich bittern, mixing, and adding Na2CO3Injecting the saturated solution and the lithium-rich halogen-forming mixed solution into the bottom of the solar cell; in Na2CO3Laying a fresh water layer 2 on the surface layer of the saturated solution and the mixed solution rich in lithium and halogen; standing for several days until the salt gradient solar cell is completely formed and enters a stable temperature rise lithium precipitation stage to obtain Na at the bottom2CO3The salt gradient solar cell comprises a saturated solution and a lithium-rich halogen-forming mixed solution. That is, in the second mode, the alkali is added during the halogen filling process, and Na is firstly added2CO3Saturated solution and high Li+Low CO3 2-The rich lithium halogen is mixed in the halogen conveying channel 7, and then the evenly mixed Na2CO3Injecting the saturated solution and the lithium-rich halogen into the bottom of the solar pond through a water pump to obtain Na at the bottom2CO3The salt gradient solar cell of the saturated solution and the mixed solution rich in lithium and halogen is injected as shown in figure 3.
In this example, Na was added to the bottom of the solar cell2CO3The volume of the saturated solution depends on Li which is filled into the solar pond and is rich in lithium to be halogen+And CO3 2-Determining the concentration by adding Na2CO3The volume ratio of the saturated solution to the lithium-rich halogen poured into the solar pond is 1:30-1: 8.
In order to inject Na into the bottom of the solar pond2CO3The saturated solution is fully mixed with the lithium-rich lithium-forming brine of the lithium precipitation layer 4, and Na of the lithium precipitation layer 4 of the solar pond is uniformly mixed by brine mixing equipment on the premise of ensuring that the transition layer 3 in the middle of the solar pond is not damaged2CO3The saturated solution and the lithium-rich halogen-forming mixed solution are subjected to mechanical disturbance and forced convection circulation.
In this embodiment, the brine mixing equipment is one or two combinations of pumping and injecting water equipment or agitated vessel.
In a preferred embodiment of the present invention, Na of the solar cell lithium deposition layer 4 is added by a stirring device2CO3The saturated solution and the lithium-rich halogen-forming mixed solution are subjected to mechanical disturbance and forced convection circulation. The stirring devices are arranged in the lithium precipitation layer 4, for example, the stirring devices are arranged at the bottom of the solar pond and/or on the side slope, a plurality of stirring devices are dispersedly placed at different positions of the bottom of the solar pond or on the side slope, and the vertical placement positions of the stirring devices in the lithium precipitation layer 4 are or are not on the same horizontal plane.
Furthermore, the stirring equipment is a submersible stirrer, one or more submersible stirrers are arranged on the side slope of the solar pond and at the bottom of the pond, and the number of the submersible stirrers is determined according to the volume of the pond body, the power of the submersible stirrers and the arrangement mode. The vertical placement position of the submersible stirrer on the solar pond slope is at or not at the same horizontal plane, the maximum vertical height of the submersible stirrer from the pond bottom is 7/10 of the thickness of the lithium precipitation layer, namely, the placement position of the submersible stirrer is in the range from the pond bottom of the solar pond to the position of 3/10 thickness of the lithium precipitation layer below the surface of the lithium precipitation layer 4, and the submersible stirrer at the highest point is not more than the position of 3/10 thickness of the lithium precipitation layer below the surface of the lithium precipitation layer 4. Through set up dive mixer at bottom of the sun pond and/or side slope, can make the brine of solar pond lithium deposition layer 4 (lower troposphere) carry out the convection current circulation to reach the effect of stirring the mixing, Li in the brine+And CO3 2-The reaction is faster and more thorough.
In a preferred mode of this embodiment, the Na of the solar cell lithium deposition layer 4 is extracted by a water pumping and injecting device2CO3The saturated solution and the lithium-rich halogen-forming mixed solution are subjected to mechanical disturbance and forced convection circulation. In particular, in the sunThe bottom of the pond is provided with water pumping and injecting equipment, a water inlet and a water outlet of the water pumping and injecting equipment are both positioned on the lithium precipitation layer 4, the water inlet of the water pumping and injecting equipment is positioned on a main body of the water pumping and injecting equipment, the water outlet of the water pumping and injecting equipment is introduced to other positions in the lithium precipitation layer 4 through a pipeline, the water pumping and injecting equipment is arranged in the lithium precipitation layer 4, the vertical arrangement positions of the water pumping and injecting equipment are the same as the height of the bottom of the solar pond, and the vertical arrangement positions in the lithium precipitation layer 4 are on the same horizontal plane; or the vertical arrangement positions of the water pumping and injecting equipment are not completely the same as the height of the bottom of the solar pond, and the vertical arrangement positions of the water pumping and injecting equipment in the lithium precipitation layer 4 are on the same horizontal plane or not. The quantity of the water pumping and injecting equipment is determined according to the volume of the pool body and the flow of the water pumping and injecting equipment.
Furthermore, in order to make the distribution of the temperature field and the concentration field of the brine in the lithium analysis layer 4 of the solar pond more uniform, a plurality of submersible pumps 5 are dispersedly arranged in the lithium analysis layer 4. In the horizontal arrangement mode, the horizontal arrangement positions of the submersible pumps 5 are in diagonal arrangement or equidistant arrangement or other arrangement modes, the number of the submersible pumps 5 is determined according to the bottom area of the solar pond, and the average number is 200-2000 m2Placing a submersible pump 5; in the vertical arrangement mode, the submersible pumps 5 are placed at a certain height from the bottom of the solar pond, the vertical placement heights of the submersible pumps 5 are different, the vertical placement positions of the submersible pumps 5 are on the same horizontal plane or not, and the maximum vertical height from the bottom of the pond is 7/10 of the thickness of the lithium separation layer in the submersible pumps 5. That is, the vertical position of the submersible pump 5 is within the range from the bottom of the solar pond to the position 3/10 below the surface of the lithium deposition layer 4, and the submersible pump 5 at the highest point is not more than 3/10 below the surface of the lithium deposition layer 4. The water outlet of the submersible pump 5 is led out to the pool bank along the side slope through the water pipe 8, and then is inserted into the other end of the pool bottom after being surrounded along the edge of the pool body, namely, the water outlet of each submersible pump 5 is connected with the water pipe 8, one end of the water outlet 9 of the water pipe is led out to the pool bank along the side slope, and then is inserted into the other end of the pool bottom after being surrounded along the edge of the pool body, a certain distance is reserved between the water inlet of the same submersible pump 5 and the water outlet 9 of the water pipe, the water inlet flow direction of the water inlet of the same submersible pump 5 is the same asA circulation path, can influence each other between the circulation path of different immersible pumps 5, open immersible pump 5 and control immersible pump 5's flow, constantly carry out circulation in separating lithium layer 4 and take out bittern and irritate the steamed operation, under the prerequisite of not destroying solar cell transition layer 3, make solar cell separate lithium layer 4's rich lithium brine form the mixed convection under mechanical disturbance, the effect of forced convection circulation, the temperature field and the concentration field distribution of promotion lithium layer 4 brine are more even, thereby improve the crystallization efficiency of lithium carbonate.
In the embodiment, the flow range of the submersible pump 5 is controlled to be 30-100 m3H to prevent turbulence and damage to the transition layers of the solar cell.
In order to realize better circulation convection stirring effect, the flow of a plurality of submersible pumps 5 is not completely the same, the circulation convection capacity of different submersible pumps 5 is controlled by controlling the flow rate of the submersible pumps 5 at different positions, and because the circulation convection capacity of each circulation path is different, the fluid motion among the circulation paths of different submersible pumps 5 influences each other, thereby the mixed convection effect of the solar pond lithium precipitation layer 4 is better.
In the embodiment, after the salt gradient solar cell is manufactured in the step 1, when the temperature of the lithium-rich formed halide in the solar cell lithium deposition layer 4 is raised to be above 30 ℃ and is raised stably, mechanical disturbance and forced convection circulation operation are performed, and the mechanical disturbance frequency is 1-10 times from the time when the lithium-rich formed halide enters the stable temperature-raising lithium deposition stage to the time when the halide is discharged. The duration of single mechanical disturbance depends on the temperature of the mixed solution of the solar cell lithium precipitation layer 4 and Li+And CO3 2-The radial distribution uniformity of the concentration is determined, and the time of single mechanical disturbance is 1-120 h.
It should be noted that, in this embodiment, an operation mode of mechanical disturbance and forced convection circulation is adopted, and the operation is not limited to the circular halogen pumping and halogen filling operation by using the submersible pump 5, and other modes such as a self-priming pump, mechanical stirring, bubbling, ultrasonic oscillation and the like can achieve the purpose of promoting the distribution of the temperature field and the concentration field of the brine in the solar cell lithium analysis layer 4 to be more uniform.
In step 3 of this example, Na is present at the bottom2CO3Carbon in salt gradient solar cell of saturated solution and lithium-rich halogen-forming mixed solutionAnd (4) after the lithium carbonate is completely precipitated, performing a brine discharge operation, and collecting lithium carbonate mixed salt. Monitoring brine (Na) in the lithium precipitation layer 4 at the bottom of the solar cell in the lithium carbonate precipitation process2CO3Mixed solution of saturated solution and lithium-rich halogen forming solution) of Li+And (4) performing brine discharge operation after the lithium carbonate is basically completely precipitated, harvesting, airing, weighing and measuring the lithium carbonate mixed salt precipitated at the bottom and the side slope of the pool. Wherein, the judgment basis for the complete precipitation of lithium carbonate in the solar cell lithium precipitation layer 4 is to monitor Li in the brine in the solar cell lithium precipitation layer 4+Concentration of when Li+The precipitation of lithium carbonate was considered complete when the concentration was 1.0g/L or less.
In this embodiment, step 1 further comprises preparing Na2CO3A saturated solution step, which specifically comprises the following steps: adding a certain amount of fresh water into the stirring tank 6, adding the industrial sodium carbonate while continuously stirring, and continuously stirring until the solution is Na2CO3Completely dissolving to obtain Na2CO3And (4) saturated solution.
It should be noted that the prepared alkali liquor should be quickly and thoroughly discharged from the stirring tank 6 as soon as possible, otherwise, the alkali liquor is susceptible to temperature reduction and a large amount of crystals are separated out, so that the scale on the inner wall of the stirring tank 6 is not easy to clean. In a preferred mode of the present embodiment, the stirring tank 6 is provided with a heater, the heater is arranged on the inner wall or the bottom of the stirring tank 6, and the heater is connected with a solar power supply device which is used for supplying power to the heater. Preparation of Na by using stirring tank 6 with heating function2CO3Saturated solution capable of allowing Na in the self-heating agitation tank 62CO3The saturated solution is maintained at a specified temperature, so that a large amount of crystals are prevented from being separated out due to temperature reduction.
Considering that the solar cell is built in a remote mountain area, the power supply can not be normally carried out in field construction, if the power distribution conditions around the large lithium-rich salt lakes in the Tibet area are very poor, the heater of the stirring tank 6 is powered by solar power supply equipment, and the heater is provided with a storage battery, so that the problem that the power supply of equipment cannot be met due to the poor power distribution conditions in the remote mountain area is solved, the stirring tank 6 can be ensured to normally work at night or in cloudy days, and the continuity of lithium extraction work is ensured.
The raising sun of the embodimentThe method for crystallization efficiency of lithium carbonate in the pond is suitable for all solar ponds, in particular for high Li in carbonate type salt lake+Low CO3 2-High Li formed in early years of each year after winter bittern-making+Low CO3 2-Halogen formation, Li in brine+Concentration is more than 1.50g/L, CO3 2-The concentration is above 15.00 g/L.
Compared with the prior art, the method for improving the crystallization efficiency of the lithium carbonate in the solar cell adopts the carbonate type salt lake with high Li content+Low CO3 2-The brine forming is used as a raw material, on the basis of temperature rise and lithium precipitation of a traditional solar pond and based on a collision nucleation principle, the crystallization efficiency of lithium carbonate is improved by a mechanical disturbance and enhanced circulation method, on the premise that a middle transition layer of the solar pond is not damaged, mechanical disturbance and forced convection circulation are carried out on brine of a lithium precipitation layer at the bottom by brine mixing equipment, and Li in the brine is greatly increased+And CO3 2-The collision combination opportunity promotes the distribution of the temperature field and the concentration field of brine of the lithium separation layer of the solar cell to be more uniform, and accelerates the crystallization separation of lithium carbonate in the solar cell, thereby greatly improving the lithium yield of the solar cell. It is also possible to artificially add CO to the lithium-rich bittern filled into the solar cell3 2-To form Li in the halogen+More with Li2CO3Form crystallization is separated out, and meanwhile, mechanical disturbance and enhanced circulation are carried out on a lithium separation layer by adopting brine mixing equipment to ensure that Na is separated out2CO3The saturated solution and the brine of the solar cell lithium analysis layer are fully mixed, so that the temperature field and the concentration field of the brine of the solar cell lithium analysis layer are distributed more uniformly, the crystallization and the separation of lithium carbonate in the solar cell are accelerated, and the lithium yield of the solar cell is greatly improved. The method of the embodiment is easy to operate, wide in application, suitable for all solar ponds, economic and environment-friendly, and capable of being popularized and implemented in production.
Example 1:
a solar pond A1 in a workshop of Tibet Zaubeya mining area is selected to carry out disturbance experiment (sodium carbonate is not added). The bottom area of the A1 solar pond is 2500m 22 submersible pumps are arranged diagonally 50cm away from the bottom of the A1 solar pond with the bittern filling depth of 2mThe power of the submersible pump is 3kw, and the flow rate of the submersible pump is 50m3H is used as the reference value. And (3) starting the first mechanical disturbance when the temperature of the concentrated lithium-rich brine in the A1 solar pond is basically stable and reaches 40 ℃, wherein the time of the first cycle is 64 hours in total. And (5) carrying out second mechanical disturbance after two months, wherein the second period duration is 50 hours in total. Longitudinally observing and sampling the A1 solar cell before and after the first disturbance and the second disturbance, and respectively carrying out Li observation on brine+The test analysis of the concentration gave the test results shown in table 1.
And after the A1 solar cell finishes lithium separation, salt collection, weighing, sampling and analysis are carried out on the solid samples in the cell after the brine discharge is finished, the weight of the lithium carbonate mixed salt obtained by the A1 solar cell is 38.53 tons, and the grade of the lithium carbonate is 78.8%.
Comparative example 1:
selecting A2 solar pond of a workshop of Tibet Zaubuye mining area as a comparison pond, wherein the bottom area of the A2 solar pond is 2500m2The depth of brine filling is 2m, and the filled concentrated lithium-rich brine is formed into the same A1 solar pond. The A2 solar cell is operated according to the traditional solar cell temperature-rising lithium-separating process without disturbance or sodium carbonate addition. Respectively carrying out longitudinal observation and sampling on the A2 solar pond after filling bittern and before discharging bittern and Li bittern+The test analysis of the concentration gave the test results shown in table 2.
And after the A2 solar cell finishes lithium separation, salt collection, weighing, sampling and analysis are carried out on the solid samples in the cell after the brine discharge is finished, the weight of the lithium carbonate mixed salt obtained by the A2 solar cell is 28.24 tons, and the grade of the lithium carbonate is 72.2%.
From example 1 and comparative example 1, it can be seen that the yield of the mixed lithium carbonate in the a1 solar cell (with disturbance and without sodium carbonate) is increased by 10.29 tons, the yield of the lithium carbonate is increased by 36.43% and the grade of the mixed lithium carbonate is increased by 6.6% compared with the a2 solar cell (without disturbance and without sodium carbonate). Therefore, in the embodiment, the brine mixing equipment is adopted to perform mechanical disturbance and forced convection circulation operation on the lithium-rich brine on the lithium precipitation layer at the bottom of the solar pond, so that the method has an obvious effect on improving the yield and the grade of the single-pond lithium carbonate mixed salt of the solar pond.
Example 2:
a B1 solar cell in a workshop of Tibet Zabunyae mining area is selected, and the method for improving the crystallization efficiency of lithium carbonate in the solar cell is utilized to carry out experiments on the B1 solar cell by heating the traditional solar cell to precipitate lithium and assisting a carbonate precipitation method. Wherein the primary halide is Li+Concentration of 2.03g/L, CO3 2-A concentration of 19.46g/L, is typically high Li+Low CO3 2-Forming halogen. The bottom area of the B1 solar pond is 2500m2And (3) pouring brine into the brine tank with the depth of 2m, paving a layer of fresh water with the thickness of 1m on the surface layer, standing for several days until the salt gradient solar pond is completely formed and enters a stable temperature rise lithium precipitation stage, and adding alkali after the temperature of the brine reaches 30 ℃ and the temperature rise is kept stable. The alkali adding mode adopts a first mode of adding 105 tons of alkali, and the alkali liquor is injected into a solar pond lithium precipitation layer through a water pump, namely prepared Na is added by 1 water pump (3kw)2CO3The saturated solution is slowly injected into the bottom of the solar pond through a pipeline, and the flow rate of a water pump is controlled to be 50m3H is used as the reference value. Respectively carrying out longitudinal observation and sampling on a B1 solar pond after adding alkali and before discharging brine, and carrying out Li observation and sampling on the brine+And CO3 2-The test analysis of the concentration gave the test results shown in table 3.
And after the lithium separation of the B1 solar cell is finished, salt collection, weighing, sampling and analysis are carried out on the solid samples in the cell after the brine discharge is finished, the weight of the lithium carbonate mixed salt obtained by the B1 solar cell is 51.64 tons, and the grade of the lithium carbonate is 78%.
Example 3:
a B2 solar cell in a workshop of Tibet Zabunyae mining area is selected, and the method for improving the crystallization efficiency of lithium carbonate in the solar cell is utilized to carry out experiments on the B2 solar cell by heating the traditional solar cell to precipitate lithium and assisting a carbonate precipitation method. Wherein the primary halide is Li+Concentration of 2.02g/L, CO3 2-The concentration is 27.73g/L, and the material belongs to high Li+Low CO3 2-Forming halogen. The bottom area of the B2 solar pond is 2500m2. The alkali adding mode adopts a second mode, wherein 108.45 tons of alkali is added, and alkali liquor and formed halogen are uniformly mixed in a halogen conveying channel and then are filled into a solar pond together, namely prepared Na2CO3Injecting saturated solution into bittern conveying channel, mixing with bittern in the bittern conveying channel, and using 1 water pump with submersible pump power of 3kw to fill the mixed solution into the bottom of solar pond, wherein the flow rate of the water pump is 50m3H is used as the reference value. And (3) pouring brine into the brine tank with the depth of 2m, laying a layer of fresh water with the thickness of 1m on the surface layer, standing for several days until the salt gradient solar pond is completely formed and enters a stable temperature rise lithium precipitation stage, wherein the temperature of the brine reaches 30 ℃. Respectively carrying out longitudinal observation and sampling on a B2 solar pond after adding alkali and before discharging brine, and carrying out Li observation and sampling on the brine+And CO3 2-The test analysis of the concentration gave the test results shown in table 4.
And after the lithium separation of the B2 solar cell is finished, salt collection, weighing, sampling and analysis are carried out on the solid samples in the cell after the brine discharge is finished, the weight of the lithium carbonate mixed salt obtained by the B2 solar cell is 63.3 tons, and the grade of the lithium carbonate is 78.25%.
Comparative example 2:
a B3 solar pond in a certain workshop of Tibet Zabunyae mining area is selected as a comparison pond, the operation is carried out according to the traditional solar pond temperature-rising lithium-separating process, a carbonate precipitation method is not adopted, and the mechanical disturbance operation is not carried out on a lithium-separating layer. Wherein the primary halide is Li+Concentration 1.80g/L, CO3 2-The concentration is 44.45g/L, and the lithium-ion battery belongs to high Li+Low CO3 2-Forming halogen. The bottom area of the B3 solar pond is 2500m2And (3) pouring brine into the brine tank with the depth of 2m, laying a layer of fresh water with the thickness of 1m on the surface layer, standing for several days until the salt gradient solar pond is completely formed and enters a stable temperature rise lithium precipitation stage, wherein the temperature of the brine reaches 30 ℃. Longitudinal observation and sampling are carried out on the B3 solar pond and the brine Li+And CO3 2-The test analysis of the concentration gave the test results shown in Table 5.
And after the lithium separation of the B3 solar cell is finished, salt collection, weighing, sampling and analysis are carried out on the solid samples in the cell after the brine discharge is finished, the weight of the lithium carbonate mixed salt obtained by the B3 solar cell is 28.24 tons, and the grade of the lithium carbonate is 72.2%.
It can be seen from examples 2, 3 and 2 that, compared with the B3 solar cell (the conventional solar cell is not mechanically agitated for lithium precipitation at elevated temperature and is not assisted by carbonate precipitation), the B1 and B2 solar cell (adopting the method of the present invention) respectively increase the yield of mixed lithium carbonate by 23.4 tons and 35.1 tons, respectively increase the yield of lithium carbonate by 82.86% and 124%, respectively, and increase the grade of mixed lithium carbonate by 5.8% and 6%, respectively. Therefore, the invention adopts the traditional solar cell to increase the temperature and separate out lithium and is assisted by a carbonate precipitation method to improve the high Li+Low CO3 2-The yield effect of the lithium for halogen formation is obvious, the yield and the grade of the single-cell lithium carbonate mixed salt are greatly improved, and the grade of the lithium carbonate can reach over 75 percent.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention.
Claims (4)
1. A method for improving crystallization efficiency of lithium carbonate in a solar cell is characterized by comprising the following steps:
step 1: carbonate type salt lake high Li+Low CO3 2-Preparing a salt gradient solar pond by taking halogen-forming raw materials;
step 2: adopting brine mixing equipment to convert lithium-rich brine and Na in the lithium precipitation layer (4) at the bottom of the salt gradient solar pond2CO3Repeatedly carrying out mechanical disturbance and forced convection circulation operation on the saturated solution for multiple times;
and step 3: after lithium carbonate in the lithium precipitation layer (4) at the bottom of the solar cell is completely precipitated, performing halogen discharge operation, and collecting lithium carbonate mixed salt;
the brine mixing equipment is one or a combination of water pumping and injecting equipment and stirring equipment; before the step 1, arranging the stirring equipment at the bottom and/or a side slope of a solar pond; the stirring devices are arranged in the lithium precipitation layer (4) and are not vertically arranged on the same horizontal plane;
the water pumping and injecting equipment is a submersible pump (5); the number of the submersible pumps (5) is multiple, and the submersible pumps (5) are dispersedly arranged in the lithium precipitation layer (4) and are not vertically arranged on the same horizontal plane.
2. The method for improving the crystallization efficiency of lithium carbonate in the solar pond according to claim 1, wherein the water outlet of the submersible pump (5) is led out to the bank along the side slope through the water pipe (8), and is inserted into the other end of the pond bottom after being surrounded along the edge of the pond body, the submersible pump (5) is started and the flow rate of the submersible pump (5) is controlled, and the circulating brine pumping and filling operation is continuously carried out in the lithium precipitation layer (4).
3. The method of claim 2 for increasing the crystallization efficiency of lithium carbonate in a solar cellThe method is characterized in that the flow range of the submersible pump (5) is 30-100 m3/h。
4. The method for improving the crystallization efficiency of lithium carbonate in a solar cell according to claim 3, characterized in that the number of submersible pumps (5) is 200-2000 m per average2A submersible pump (5) is placed.
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