阅读说明：本技术 盐湖卤水的提锂系统和提锂方法 (Lithium extraction system and method for salt lake brine ) 是由 周文龙 羡鹏飞 邱爽 杨永亮 徐长庆 杜国山 于 2021-01-29 设计创作，主要内容包括：本发明提供了一种盐湖卤水的提锂系统和提锂方法。该提锂系统包括：连续除镁设备、连续沉锂设备以及连续洗涤设备；连续除镁设备用于采用氢氧化钠溶液对富锂卤水进行连续除镁处理,得到除镁后液和镁渣；连续沉锂设备与连续除镁设备相连,用于将除镁后液进行连续沉锂处理,得到粗碳酸锂和沉锂母液；以及连续洗涤设备与连续沉锂设备相连,用于将粗碳酸锂进行连续洗涤处理,得到碳酸锂固体。本申请创造性的采用盐湖卤水的提锂系统,这样的一体化提锂系统能够做到连续性生产,从而显著降低劳动强度,并减少因人工操控主观区别导致的产品差异,进而提高了产品的质量稳定性,降低了产品成本,提高了碳酸锂产品的批次合格性。(The invention provides a lithium extraction system and a lithium extraction method for salt lake brine. This lithium system of carrying includes: continuous magnesium removing equipment, continuous lithium depositing equipment and continuous washing equipment; the continuous magnesium removal equipment is used for carrying out continuous magnesium removal treatment on the lithium-rich brine by adopting a sodium hydroxide solution to obtain a magnesium-removed liquid and magnesium slag; the continuous lithium precipitation equipment is connected with the continuous magnesium removal equipment and is used for carrying out continuous lithium precipitation treatment on the magnesium-removed liquid to obtain crude lithium carbonate and a lithium precipitation mother liquid; and the continuous washing equipment is connected with the continuous lithium precipitation equipment and is used for continuously washing the crude lithium carbonate to obtain a lithium carbonate solid. According to the lithium extraction system creatively adopting salt lake brine, the integrated lithium extraction system can realize continuous production, so that the labor intensity is obviously reduced, the product difference caused by manual control subjective distinction is reduced, the quality stability of the product is improved, the product cost is reduced, and the batch qualification of lithium carbonate products is improved.)

1. A lithium extraction system of salt lake brine, characterized in that, the lithium extraction system includes:

the continuous magnesium removal equipment (01) is used for carrying out continuous magnesium removal treatment on the lithium-rich brine by adopting a sodium hydroxide solution to obtain a magnesium-removed liquid and magnesium slag;

the continuous lithium precipitation equipment (02) is connected with the continuous magnesium removal equipment (01) and is used for carrying out continuous lithium precipitation treatment on the magnesium-removed liquid to obtain crude lithium carbonate and a lithium precipitation mother liquid; and

and the continuous washing equipment (03) is connected with the continuous lithium deposition equipment (02) and is used for continuously washing the crude lithium carbonate to obtain a lithium carbonate solid.

2. The lithium extraction system according to claim 1, characterized in that the continuous magnesium removal device (01) comprises:

a continuous magnesium deposition device (011) for carrying out continuous magnesium removal treatment on the lithium-rich brine by adopting the sodium hydroxide solution to obtain a first slurry;

the first continuous sedimentation device (012) is connected with the continuous magnesium sedimentation device (011) and is used for carrying out first solid-liquid separation on the first slurry to obtain a first underflow and a first overflow liquid; and

the continuous solid-liquid separation device is connected with the first continuous sedimentation device (012) and is used for carrying out first continuous solid-liquid separation on the first underflow to obtain the magnesium slag and the magnesium-removed liquid;

preferably, the continuous magnesium precipitation device (011) comprises at least one continuous magnesium precipitation tank (015), preferably, the continuous magnesium precipitation device (011) comprises two to five continuous magnesium precipitation tanks (015) connected in series, preferably, the continuous solid-liquid separation device comprises a first continuous filter (013) and a first continuous fine filter (014) which are sequentially connected, and preferably, the continuous magnesium precipitation device (011) is provided with a edulcorant feeder.

3. The lithium extraction system according to claim 1 or 2, characterized in that the continuous lithium deposition device (02) comprises:

a continuous lithium deposition device (021) for performing the continuous lithium deposition treatment on the magnesium-removed liquid by adopting a sodium carbonate solution to obtain second slurry;

the second continuous settling device (022) is connected with the continuous lithium settling device (021) and is used for carrying out second solid-liquid separation on the second slurry to obtain a second underflow and a second overflow liquid; and

a second continuous filter (023) connected to the second continuous settling device (022) for performing a second continuous solid-liquid separation on the second underflow to obtain the crude lithium carbonate and the lithium-settling mother liquor;

an optional second continuous fine filter (024) which is connected with the second continuous filter (023) and the second continuous sedimentation device (022) respectively and is used for carrying out third continuous solid-liquid separation on the second overflow liquid and the lithium precipitation mother liquid to obtain a fine filter liquid and a fine filter residue, wherein the optional second continuous fine filter (024) and the continuous lithium precipitation device (021) and/or the second continuous sedimentation device (022) form a circulation loop for returning the fine filter residue to the continuous lithium precipitation device (021) and/or the second continuous sedimentation device (022);

preferably, the continuous lithium deposition device (021) comprises at least one continuous lithium deposition tank (025), preferably the continuous lithium deposition device (021) comprises two to five continuous lithium deposition tanks (025) connected in series, preferably the continuous lithium deposition device (021) is provided with an impurity removing agent feeder.

4. A lithium extraction system according to any one of claims 1 to 3, characterized in that the continuous washing device (03) comprises:

a continuous washing device (031) for performing the continuous washing treatment on the crude lithium carbonate to obtain a third underflow and a third overflow liquid;

a third continuous filter (032) connected to the continuous washing apparatus (031) and configured to perform a fourth continuous solid-liquid separation on the third underflow, so as to obtain the lithium carbonate solid;

an optional third continuous fine filter (033) connected to the inlet and the outlet of the continuous washing device (031), respectively, for performing a fifth continuous solid-liquid separation on the third overflow liquid to obtain a fine filtered water, and returning the fine filtered water to the preparation process of the sodium carbonate solution;

preferably, the continuous washing apparatus (031) comprises at least one continuous washing tank (034), preferably the continuous washing apparatus (031) comprises two to five continuous washing tanks (034) in series.

5. A lithium extraction system according to claim 2, characterized in that the continuous magnesium precipitation bath (015) comprises an atomization device for spraying the sodium hydroxide solution into the continuous magnesium precipitation bath (015).

6. The lithium extraction system according to claim 1, further comprising a buffer homogenizer (04), wherein the buffer homogenizer (04) is a buffer homogenizing tank or a buffer homogenizing storage tank, and the buffer homogenizer (04) is connected with the continuous magnesium removal equipment (01) and is used for naturally settling the lithium-rich brine for the purpose of buffer homogenizing.

7. A lithium extraction method of salt lake brine is characterized by comprising the following steps:

step S1, carrying out continuous magnesium removal treatment on the lithium-rich brine by using a sodium hydroxide solution to obtain a magnesium-removed liquid and magnesium slag;

step S2, continuously precipitating lithium from the magnesium-removed solution to obtain crude lithium carbonate and a lithium precipitation mother solution; and

and step S3, continuously washing the crude lithium carbonate to obtain solid lithium carbonate.

8. The lithium extraction method according to claim 7, wherein the step S1 comprises:

step S11, performing the continuous magnesium removal treatment on the lithium-rich brine by using the sodium hydroxide solution to obtain a first slurry;

step S12, carrying out first settling separation on the first slurry to obtain a first underflow and a first overflow liquid; and

step S13, carrying out first continuous solid-liquid separation on the first bottom flow to obtain the magnesium slag and the magnesium-removed liquid,

preferably, the step S13 includes:

sequentially carrying out first continuous filtration and first continuous fine filtration on the first bottom flow to obtain the magnesium slag and the magnesium-removed liquid,

preferably, an impurity removing agent is added in the process of the first continuous filtration, the magnesium slag is preferably returned to the continuous magnesium removal treatment, the sodium hydroxide solution is preferably sprayed into the lithium-rich brine in a spraying manner,

preferably, before the step S11, the lithium-rich brine is subjected to a buffer homogenization treatment, and preferably, a flocculant and a filter aid are added during the first settling separation.

9. The lithium extraction method according to claim 7 or 8, wherein the step S2 includes:

step S21, performing continuous lithium precipitation treatment on the magnesium-removed liquid by using a sodium carbonate solution to obtain a second slurry, wherein the temperature of the continuous lithium precipitation treatment is preferably 90-95 ℃;

step S22, carrying out second settling separation on the second slurry to obtain a second underflow and a second overflow liquid; and

step S23, carrying out second continuous solid-liquid separation on the second bottom flow to obtain the crude lithium carbonate and the lithium deposition mother solution,

the second continuous solid-liquid separation is a continuous filtration,

optionally, carrying out second continuous fine filtration on the second overflow liquid and the lithium precipitation mother liquor to obtain fine filtration liquid and fine filtration residues;

optionally, lithium in the fine filtration liquid and the lithium precipitation mother liquid is recovered, and optionally, the fine filtration residue is returned to the second precipitation separation and/or the second precipitation separation.

10. The lithium extraction method according to any one of claims 7 to 9, wherein the step S3 includes:

step S31, performing the continuous washing treatment on the crude lithium carbonate by using water to obtain a third underflow and a third overflow liquid;

step S32, carrying out third continuous solid-liquid separation on the third bottom flow to obtain the lithium carbonate solid,

preferably the third continuous solid liquid separation is a continuous filtration,

optionally, subjecting the third overflow liquid to third continuous fine filtration to obtain fine filtered water, and

optionally, the fine filtered water is returned to the preparation process of the sodium carbonate solution.

11. The method of any one of claims 7 to 10, further comprising extracting lithium

And drying the lithium carbonate solid to obtain dry lithium carbonate.

Technical Field

The invention relates to the technical field of brine extraction of salt lakes, in particular to a lithium extraction system and a lithium extraction method of salt lake brine.

Background

The salt lake brine is one of the main raw materials for extracting lithium at present, accounts for 66% of the world lithium resource reserves, and the other is granite pegmatite type lithium ore. The lithium-containing salt lakes are classified into 3 types of carbonate, sulfate (sodium sulfate, magnesium sulfate, etc.) and chloride, which are distributed very unevenly, mainly in south america andes (argentina, bolivia, chile), chinese tibetan plateau and north america, nevada.

The magnesium-lithium ratio of foreign salt lake is low, the lithium can be extracted by precipitation method, the relative process technology is simple, and the product quality is stable. However, the Mg/Li ratio of the lithium-rich salt lake brine in China is higher and far higher than 8.0 of the Wuliya oolong salt lake, the difficulty of lithium extraction technology is high, and the cost is high, which is one of the reasons that the yield of the salt lake brine in China cannot be improved in recent years and the product quality cannot meet the requirement.

Because of different components, Mg/Li ratio and the like, lithium carbonate is generally industrially produced from lithium-rich brine by adopting different process routes such as a membrane separation method, a calcination method, an adsorption method and the like. In addition, enterprises adopt a process route of a gradient solar pond and a causticization process or a process route of a halogen exchange method and a causticization method. At present, domestic salt lake lithium extraction enterprises are basically 'one lake one process'. Among the above-mentioned resources in China, the enterprises implementing mass production are mainly located in Qinghai Chauda, while those in the Chauda basin adopt different production processes from low-concentration Li⁺High concentration of Mg²⁺Preparing the brine containing higher-concentration Li from the initial salt lake⁺Low concentration of Mg²⁺The lithium-rich brine is used for lithium precipitation discontinuous production through a discontinuous process, manual operation is mainly used, a large amount of labor input is needed, and the subjective operation differences of different personnel and different periods are large, so that the product quality is unstable, and further the product quality in a salt lake region is always low.

Disclosure of Invention

The invention mainly aims to provide a lithium extraction system and a lithium extraction method for salt lake brine, so as to solve the problem of unstable product quality obtained by a salt lake lithium extraction technology in the prior art.

In order to achieve the above object, according to one aspect of the present invention, there is provided a lithium extraction system of salt lake brine, including: continuous magnesium removing equipment, continuous lithium depositing equipment and continuous washing equipment; the continuous magnesium removal equipment is used for carrying out continuous magnesium removal treatment on the lithium-rich brine by adopting a sodium hydroxide solution to obtain a magnesium-removed liquid and magnesium slag; the continuous lithium precipitation equipment is connected with the continuous magnesium removal equipment and is used for carrying out continuous lithium precipitation treatment on the magnesium-removed liquid to obtain crude lithium carbonate and a lithium precipitation mother liquid; and the continuous washing equipment is connected with the continuous lithium precipitation equipment and is used for continuously washing the crude lithium carbonate to obtain a lithium carbonate solid.

Further, the continuous magnesium removing apparatus comprises: the continuous magnesium precipitation device is used for carrying out continuous magnesium removal treatment on the lithium-rich brine by adopting a sodium hydroxide solution to obtain first slurry; the first continuous sedimentation device is connected with the continuous magnesium sedimentation device and is used for carrying out first solid-liquid separation on the first slurry to obtain a first underflow and a first overflow liquid; the continuous solid-liquid separation device is connected with the first continuous sedimentation device and is used for carrying out first continuous solid-liquid separation on the first bottom flow to obtain magnesium slag and magnesium-removed liquid; preferably, the continuous magnesium precipitation device comprises at least one continuous magnesium precipitation tank, preferably, the continuous magnesium precipitation device comprises two to five continuous magnesium precipitation tanks connected in series, preferably, the continuous solid-liquid separation device comprises a first continuous filter and a first continuous fine filter which are sequentially connected, and preferably, the continuous magnesium precipitation device is provided with an impurity removing agent feeder.

Further, the above-mentioned continuous lithium deposition apparatus includes: the continuous lithium precipitation device is used for carrying out continuous lithium precipitation treatment on the magnesium-removed liquid by adopting a sodium carbonate solution to obtain second slurry; the second continuous settling device is connected with the continuous lithium settling device and is used for carrying out second solid-liquid separation on the second slurry to obtain a second underflow and a second overflow liquid; the second continuous filter is connected with the second continuous settling device and is used for carrying out second continuous solid-liquid separation on the second bottom flow to obtain crude lithium carbonate and a lithium deposition mother solution; an optional second continuous fine filter is respectively connected with the second continuous filter and the second continuous sedimentation device and is used for carrying out third continuous solid-liquid separation on the second overflow liquid and the lithium precipitation mother liquid to obtain fine filter liquid and fine filter residues; optionally, the second continuous fine filter and the continuous lithium precipitation device and/or the second continuous precipitation device form a circulation loop for returning fine filter residues to the continuous lithium precipitation device and/or the second continuous precipitation device; preferably, the continuous lithium deposition device comprises at least one continuous lithium deposition tank, preferably comprises two to five continuous lithium deposition tanks connected in series, and is provided with an impurity removing agent feeder.

Further, the above continuous washing apparatus includes: the continuous washing device is used for continuously washing the crude lithium carbonate to obtain a third underflow and a third overflow liquid; the third continuous filter is connected with the continuous washing device and is used for carrying out fourth continuous solid-liquid separation on the third bottom flow to obtain lithium carbonate solid; an optional third continuous fine filter is respectively connected with an inlet and an outlet of the continuous washing device and used for carrying out fifth continuous solid-liquid separation on the third overflow liquid to obtain fine filter water and returning the fine filter water to the preparation process of the sodium carbonate solution; preferably the continuous washing apparatus comprises at least one continuous washing tank, preferably the continuous washing apparatus comprises two to five continuous washing tanks in series.

Further, the continuous magnesium precipitation tank comprises an atomization device which is used for spraying the sodium hydroxide solution into the continuous magnesium precipitation tank.

Furthermore, the lithium extraction system also comprises a buffer homogenizer which is a buffer homogenizing pool or a buffer homogenizing storage tank, and the buffer homogenizer is connected with the continuous magnesium removal equipment and used for naturally settling the lithium-rich brine to achieve the purpose of buffer homogenization.

According to another aspect of the invention, a lithium extraction method of salt lake brine is provided, and the lithium extraction method comprises the following steps: step S1, carrying out continuous magnesium removal treatment on the lithium-rich brine by using a sodium hydroxide solution to obtain a magnesium-removed liquid and magnesium slag; step S2, continuously precipitating lithium from the magnesium-removed solution to obtain crude lithium carbonate and a lithium precipitation mother solution; and step S3, continuously washing the crude lithium carbonate to obtain solid lithium carbonate.

Further, the step S1 includes: step S11, carrying out continuous magnesium removal treatment on the lithium-rich brine by using a sodium hydroxide solution to obtain first slurry; step S12, carrying out first settling separation on the first slurry to obtain a first underflow and a first overflow liquid; and step S13, the first bottom flow is subjected to first continuous solid-liquid separation to obtain the magnesium slag and the magnesium-removed liquid, and the preferable step S13 comprises the following steps: and sequentially carrying out first continuous filtration and first continuous fine filtration on the first bottom flow to obtain magnesium slag and a magnesium-removed liquid, preferably adding an impurity removing agent in the process of the first continuous filtration, preferably returning the magnesium slag to the continuous magnesium removal treatment, preferably spraying a sodium hydroxide solution into the lithium-rich brine in a spraying manner, preferably carrying out buffer homogenization treatment on the lithium-rich brine before step S11, and preferably adding a flocculating agent and a filter aid in the process of the first sedimentation separation.

Further, the step S2 includes: step S21, adopting a sodium carbonate solution to carry out continuous lithium precipitation treatment on the magnesium-removed solution to obtain a second slurry, wherein the temperature of the continuous lithium precipitation treatment is preferably 90-95 ℃; step S22, carrying out second settling separation on the second slurry to obtain a second underflow and a second overflow liquid; and step S23, performing second continuous solid-liquid separation on the second bottom flow to obtain crude lithium carbonate and lithium precipitation mother liquor, wherein the second continuous solid-liquid separation is continuous filtration, and optionally performing second continuous fine filtration on the second overflow liquid and the lithium precipitation mother liquor to obtain fine filtration liquid and fine filtration slag; optionally, lithium in the fine filtration liquid and the lithium precipitation mother liquid is recovered, and optionally, the fine filtration residue is returned to the second precipitation separation and/or the second precipitation separation.

Further, the step S3 includes: step S31, continuously washing the crude lithium carbonate by using water to obtain a third underflow and a third overflow liquid; and step S32, performing third continuous solid-liquid separation on the third underflow to obtain lithium carbonate solid, preferably, performing continuous filtration on the third continuous solid-liquid separation, optionally, performing third continuous fine filtration on the third overflow liquid to obtain fine filtration water, and optionally, returning the fine filtration water to the preparation process of the sodium carbonate solution.

Further, the lithium extraction method further comprises drying the lithium carbonate solid to obtain dried lithium carbonate.

By applying the technical scheme, the lithium extraction system adopting the salt lake brine comprises continuous magnesium removal equipment, continuous lithium precipitation equipment and continuous washing equipment which are sequentially connected. The integrated lithium extraction system can achieve continuous production, so that the labor intensity is obviously reduced, the product difference caused by manual control subjective distinction is reduced, the quality stability of products is improved, the product cost is reduced, and the batch qualification of lithium carbonate products is improved.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:

fig. 1 shows a schematic diagram of a lithium extraction system of salt lake brine provided in example 1 of the present invention;

FIG. 2 shows a simple lithium extraction process flow diagram of salt lake brine provided by the present application; and

fig. 3 shows a lithium extraction process flow diagram of the salt lake brine provided in example 1.

Wherein the figures include the following reference numerals:

01. continuous magnesium removal equipment; 02. continuous lithium deposition equipment; 03. continuous washing equipment; 04. a buffer homogenizer; 011. a continuous magnesium precipitation device; 012. a first continuous settling device; 013. a first continuous filter; 014. a first continuous fine filter; 015. a continuous magnesium precipitation tank; 021. a continuous lithium deposition device; 022. a second continuous settling device; 023. a second continuous filter; 024. a second continuous fine filter; 025. continuously precipitating a lithium tank; 031. a continuous washing device; 032. a third continuous filter; 033. a third continuous fine filter; 034. the tank is continuously washed.

Detailed Description

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.

As analyzed by the background art, the problem of unstable product quality obtained by a salt lake lithium extraction technology exists in the prior art, and in order to solve the problem, the invention provides a lithium extraction system and a lithium extraction method for salt lake brine.

In an exemplary embodiment of the present application, there is provided a lithium extraction system of salt lake brine, as shown in fig. 1, the lithium extraction system including: the device comprises a continuous magnesium removing device 01, a continuous lithium depositing device 02 and a continuous washing device 03; the continuous magnesium removal equipment 01 is used for carrying out continuous magnesium removal treatment on the lithium-rich brine by adopting a sodium hydroxide solution to obtain a magnesium-removed liquid and magnesium slag; the continuous lithium precipitation equipment 02 is connected with the continuous magnesium removal equipment 01 and is used for carrying out continuous lithium precipitation treatment on the magnesium-removed liquid to obtain crude lithium carbonate and a lithium precipitation mother liquid; and the continuous washing equipment 03 is connected with the continuous lithium precipitation equipment 02 and is used for continuously washing the crude lithium carbonate to obtain a lithium carbonate solid.

This application adopts the lithium system of carrying of salt lake brine, and this system is including the continuous magnesium equipment 01 that removes, the lithium equipment 02 and the continuous washing equipment 03 of sinking that connect gradually. The integrated lithium extraction system can achieve continuous production, so that the labor intensity is obviously reduced, the product difference caused by manual control subjective distinction is reduced, the quality stability of products is improved, the product cost is reduced, and the batch qualification of lithium carbonate products is improved.

In one embodiment of the present application, as shown in fig. 1, the continuous magnesium removal apparatus 01 includes: a continuous magnesium-precipitating device 011, a first continuous precipitating device 012 and a continuous solid-liquid separating device; the continuous magnesium settling device 011 is used for carrying out continuous magnesium removal treatment on the lithium-rich brine by adopting a sodium hydroxide solution to obtain first slurry; the first continuous sedimentation device 012 is connected with the continuous magnesium sedimentation device 011 and is used for carrying out first solid-liquid separation on the first slurry to obtain a first underflow and a first overflow liquid; and the continuous solid-liquid separation device is connected with the first continuous sedimentation device 012 and is used for carrying out first continuous solid-liquid separation on the first underflow to obtain magnesium slag and a magnesium-removed liquid; the continuous magnesium precipitating device 011 preferably comprises at least one continuous magnesium precipitating tank 015, the continuous magnesium precipitating device 011 preferably comprises two to five continuous magnesium precipitating tanks 015 connected in series, the continuous solid-liquid separating device preferably comprises a first continuous filter 013 and a first continuous fine filter 014 which are sequentially connected, and the continuous magnesium precipitating device 011 preferably is provided with an impurity removing agent feeder.

With reference to the schematic diagram of the lithium extraction system of the salt lake brine shown in fig. 1, it can be seen that in the continuous magnesium removal equipment 01, continuous magnesium removal treatment, first solid-liquid separation and first continuous solid-liquid separation are sequentially performed in the continuous magnesium precipitation device 011, the first continuous precipitation device 012 and the continuous solid-liquid separation device which are sequentially connected, so that the purpose of continuous magnesium removal of the lithium-rich brine is achieved, the influence of human factors is avoided, and the quality stability of the magnesium-removed solution is improved. In order to facilitate the feeding of the first slurry into the first continuous sedimentation device 012, it is preferable that a pump is provided between the continuous magnesium precipitation tank 015 and the first continuous sedimentation device 012 to pump the first slurry into the first continuous sedimentation device 012. In order to control the sedimentation of the first slurry in the first continuous sedimentation device 012, a temperature-controlled stirrer is preferably provided in the first continuous sedimentation device 012. It is preferable to provide a mechanical stirrer in the continuous magnesium precipitation bath 015 to assist in the efficient performance of the continuous magnesium removal process.

In order to facilitate the supply of the sodium hydroxide solution, a sodium hydroxide solution supply device may be provided, which is connected to the continuous magnesium precipitation device 011 and to which the sodium hydroxide solution is supplied.

In an embodiment of the present application, as shown in fig. 1, the continuous lithium deposition apparatus 02 includes: a continuous lithium deposition device 021, a second continuous deposition device 022, and a second continuous filter 023; the continuous lithium precipitation device 021 is used for carrying out continuous lithium precipitation treatment on the magnesium-removed liquid by adopting a sodium carbonate solution to obtain second slurry; the second continuous settling device 022 is connected with the continuous lithium settling device 021 and is used for carrying out second solid-liquid separation on the second slurry to obtain a second underflow and a second overflow liquid; the second continuous filter 023 is connected with the second continuous settling device 022 and is used for carrying out second continuous solid-liquid separation on the second underflow to obtain crude lithium carbonate and a lithium-settling mother solution; an optional second continuous fine filter 024 is connected with the second continuous filter 023 and the second continuous sedimentation device 022 respectively and is used for carrying out third continuous solid-liquid separation on the second overflow liquid and the lithium precipitation mother liquid to obtain fine filter liquid and fine filter residue, and the optional second continuous fine filter 024 and the continuous lithium precipitation device 021 and/or the second continuous sedimentation device 022 form a circulation loop for returning the fine filter residue to the continuous lithium precipitation device 021 and/or the second continuous sedimentation device 022; preferably, the continuous lithium deposition apparatus 021 comprises at least one continuous lithium deposition tank 025, preferably the continuous lithium deposition apparatus 021 comprises two to five continuous lithium deposition tanks 025 connected in series, and preferably the continuous lithium deposition apparatus 021 is provided with an impurity removing agent feeder.

By combining the schematic diagram of the lithium extraction system of the salt lake brine shown in fig. 1, it can be seen that the first continuous fine filter 014, the continuous lithium precipitation device 021, the second continuous precipitation device 022 and the second continuous filter 023 in the continuous magnesium removal equipment 01 are sequentially connected, so that the magnesium-removed liquid obtained in the continuous magnesium removal equipment 01 can be subjected to continuous lithium precipitation treatment to obtain crude lithium carbonate, the influence of human factors is avoided, and the quality stability of the crude lithium carbonate is improved. Wherein, two to five continuous lithium precipitation tanks 025 connected in series can carry out continuous lithium precipitation treatment on the magnesium-removed liquid more fully, and can increase the treatment capacity of the magnesium-removed liquid according to actual needs. The configuration of the impurity removing agent feeder on the continuous lithium deposition device 021 can selectively add the impurity removing agent according to the actual situation of the continuous lithium deposition treatment process so as to further improve the effect of the continuous lithium deposition treatment. A pump is preferably provided between the continuous lithium precipitation tank 025 and the second continuous precipitation device 022 to pump the second slurry into the second continuous precipitation device 022. Preferably, a temperature-controlled stirrer is arranged in the second continuous settling device 022 to regulate the second solid-liquid separation process. It is preferable to provide a mechanical stirrer in the continuous magnesium precipitation bath 015 to assist in the efficient performance of the continuous lithium precipitation process.

In order to provide the sodium carbonate solution, a sodium carbonate solution supply device may be provided and connected to the continuous lithium deposition device 021 to supply the sodium carbonate solution thereto.

In an embodiment of the present application, as shown in fig. 1, the above-mentioned continuous washing apparatus 03 includes: a continuous washing device 031 and a third continuous filter 032; the continuous washing device 031 continuously washes the coarse lithium carbonate to obtain a third underflow and a third overflow liquid; the third continuous filter 032 is connected to the continuous washing device 031, and is configured to perform a fourth continuous solid-liquid separation on the third underflow, so as to obtain a lithium carbonate solid; an optional third continuous fine filter 033 is connected to an inlet and an outlet of the continuous washing device 031, respectively, and is used for performing fifth continuous solid-liquid separation on the third overflow liquid to obtain fine filter water, and returning the fine filter water to the preparation process of the sodium carbonate solution; preferably, the continuous washing apparatus 031 comprises at least one continuous washing tank 034, and preferably, the continuous washing apparatus 031 comprises two to five continuous washing tanks 034 connected in series.

With reference to the schematic diagram of the lithium extraction system of the salt lake brine shown in fig. 1, it can be seen that the second continuous filter 023 of the continuous lithium deposition device 02 is connected to the continuous washing device 031 of the continuous washing device 03, and the continuous washing device 031 and the third continuous filter 032 are sequentially connected, so that the continuous washing treatment of the coarse lithium carbonate is realized, the lithium carbonate solid is obtained, and the difference in lithium carbonate solids caused by the subjective difference of manual operation and control is reduced.

To further contact the sodium hydroxide solution with the lithium-rich brine more sufficiently to improve the efficiency of the continuous magnesium removal process, it is preferable that the continuous magnesium precipitation bath 015 includes an atomizing device for spraying the sodium hydroxide solution into the continuous magnesium precipitation bath 015.

In an embodiment of the present application, as shown in fig. 1, the lithium extraction system further includes a buffer homogenizer 04, the buffer homogenizer 04 is a buffer homogenizing tank or a buffer homogenizing storage tank, and the buffer homogenizer 04 is connected to the continuous magnesium removal apparatus 01 for naturally settling the lithium-rich brine for the purpose of buffer homogenizing.

The buffer homogenizer 04 is used for storing lithium-rich brine (raw material for producing lithium salt, Li)⁺>15g/L), the storage period can be properly prolonged or the storage capacity can be increased according to the stable supply capacity and the investment condition of the lithium-rich brine raw material. In order to further avoid secondary pollution to the lithium-rich brine, the buffer homogenizer 04 is preferably a closed buffer tank or a closed buffer storage tank; in order to prolong the residence time of the lithium-rich brine, a flow guide weir is preferably arranged in the buffer homogenizer to achieve the purposes of naturally settling micro-solid, homogenizing and stabilizing the latter-stage production; further onPreferably, the bottom of the buffer homogenizer is sloped to provide periodic cleaning of trace solids in the lithium-rich brine.

In another exemplary embodiment of the present application, there is provided a method for extracting lithium from salt lake brine, referring to fig. 2 or 3, the method comprising: step S1, carrying out continuous magnesium removal treatment on the lithium-rich brine by using a sodium hydroxide solution to obtain a magnesium-removed liquid and magnesium slag; step S2, continuously precipitating lithium from the magnesium-removed solution to obtain crude lithium carbonate and a lithium precipitation mother solution; and step S3, continuously washing the crude lithium carbonate to obtain solid lithium carbonate.

The lithium extraction method of the salt lake brine is adopted, and comprises continuous magnesium removal treatment, continuous lithium precipitation treatment and continuous washing treatment which are sequentially carried out on the lithium-rich brine, so that continuous production of lithium extraction of the salt lake brine is realized, the labor intensity is obviously reduced, product differences caused by subjective differences of manual operation and control are reduced, the quality stability of products is further improved, the product cost is reduced, and the batch qualification of lithium carbonate products is improved.

In an embodiment of the present application, as shown in fig. 3, the step S1 includes: step S11, carrying out continuous magnesium removal treatment on the lithium-rich brine by using a sodium hydroxide solution to obtain first slurry; step S12, carrying out first settling separation on the first slurry to obtain a first underflow and a first overflow liquid; and step S13, the first bottom flow is carried out the first continuous solid-liquid separation to obtain magnesium slag and magnesium-removed liquid, preferably step S13 comprises: and sequentially carrying out first continuous filtration and first continuous fine filtration on the first bottom flow to obtain magnesium slag and a magnesium-removed liquid, preferably adding an impurity removing agent in the process of the first continuous filtration, preferably returning the magnesium slag to the continuous magnesium removal treatment, preferably spraying a sodium hydroxide solution into the lithium-rich brine in a spraying manner, preferably carrying out buffer homogenization treatment on the lithium-rich brine before step S11, and preferably adding a flocculating agent and a filter aid in the process of the first sedimentation separation.

The above step S1 of the present application can realize continuous magnesium removal treatment of the lithium-rich brine, and obtain a magnesium-removed solution with stable quality. The above-mentioned buffer homogenization treatment of lithium-rich brine can make the trace solid in the lithium-rich brine naturally settle, so that the goal of homogenization and stable later-stage production can be achieved. Adding a flocculating agent (such as 100-250 mg/kg of anionic polyacrylamide) and a filter aid (such as diatomite) in the first solid-liquid separation process, preferably adding an impurity removing agent in the first continuous solid-liquid separation process, which is favorable for reducing the impurity content in the magnesium-removed liquid, preferably returning the magnesium slag to the continuous magnesium removal treatment as seed crystals, which is favorable for causing the magnesium hydroxide to precipitate on the surface of the seed crystals to grow up to form the aggregated magnesium hydroxide slag with a certain particle size. The sodium hydroxide solution (30-40 wt%) is preferably sprayed into the lithium-rich brine in a mist-like flow-controllable manner, so that the sodium hydroxide solution and the lithium-rich brine can be mixed more sufficiently, and the efficiency of continuous magnesium removal treatment is improved. Of course, the process of continuous magnesium removal treatment on lithium-rich brine can also refer to the prior art by those skilled in the art, and is not described herein again.

In an embodiment of the present application, as shown in fig. 3, the step S2 includes: step S21, adopting a sodium carbonate solution to carry out continuous lithium precipitation treatment on the magnesium-removed solution to obtain a second slurry; preferably, the temperature of the continuous lithium deposition treatment is 90-95 ℃; step S22, carrying out second settling separation on the second slurry to obtain a second underflow and a second overflow liquid; and step S23, performing second continuous solid-liquid separation on the second bottom flow to obtain crude lithium carbonate and lithium precipitation mother liquor, wherein the second continuous solid-liquid separation is continuous filtration, and optionally performing second continuous fine filtration on the second overflow liquid and the lithium precipitation mother liquor to obtain fine filtration liquid and fine filtration slag; optionally, lithium in the fine filtration liquid and the lithium precipitation mother liquid is recovered, and optionally, the fine filtration residue is returned to the second precipitation separation and/or the second precipitation separation.

Referring to the lithium extraction process flow chart of the salt lake brine shown in fig. 3, it can be seen that the step S2 can achieve the purpose of obtaining crude lithium carbonate through continuous lithium precipitation treatment of the magnesium-removed solution. In order to improve the precipitation efficiency of lithium carbonate, the temperature for continuous lithium precipitation treatment is preferably 90-95 ℃, and the fine filtration slag is returned for recycling, so that the waste utilization rate can be further improved, and the cost is reduced. The process of the continuous lithium deposition treatment of the magnesium-removed solution by the sodium carbonate solution can refer to the prior art, and is not repeated herein.

In order to further increase the purity of lithium carbonate, as shown in fig. 3, the step S3 preferably includes: step S31, continuously washing the crude lithium carbonate by using water to obtain a third underflow and a third overflow liquid; and step S32, performing third continuous solid-liquid separation on the third bottom flow to obtain lithium carbonate solid, preferably performing continuous filtration on the third continuous solid-liquid separation, optionally performing third continuous fine filtration on the third overflow liquid to obtain fine filtration water, and optionally returning the fine filtration water to the preparation process of the sodium carbonate solution, so that the reuse of the fine filtration water and the further recovery of lithium are realized, the water consumption is reduced, and the cost is reduced, wherein in order to balance the washing effect and the water consumption, the liquid-solid ratio of water to crude lithium carbonate is preferably 3-7: 1.

In an embodiment of the present application, as shown in fig. 3, the lithium extraction method further includes drying the lithium carbonate solid to obtain dried lithium carbonate; and packaging the dried lithium carbonate to obtain a lithium carbonate product.

And drying and packaging the lithium carbonate solid obtained after washing and purification are carried out, so that the product difference caused by manual control subjective distinction can be avoided from beginning to end, the quality stability of the product is further improved, and the batch qualification of the lithium carbonate product is improved.

The following description will explain advantageous effects of the present application with reference to specific examples.

The following example refers to a lithium extraction process flow of salt lake brine as shown in fig. 3 and a lithium extraction system as shown in fig. 1, and lithium extraction is performed on lithium-rich brine.

Example 1

The lithium-rich brine (Li) is naturally settled and homogenized in a buffer homogenizer 04 and stored for a certain period of time⁺>15g/L) of the lithium-rich brine, the composition of which is shown in Table 1, the lithium-rich brine is subjected to continuous magnesium removal treatment in a continuous magnesium removal device 01, specifically, the lithium-rich brine subjected to buffer homogenization treatment and 30 wt% of sodium hydroxide solution (sprayed into a continuous magnesium precipitation tank in a mist-like flow-controllable manner) are subjected to continuous magnesium removal treatment (at a temperature of 95 ℃) in three continuous magnesium precipitation tanks 015 of a continuous magnesium precipitation device 011 to obtain a first slurryLiquid; pumping the first slurry into a first continuous sedimentation device 012 to perform first sedimentation separation (200 mg/kg of anionic polyacrylamide and diatomite are added, wherein the addition amount of the diatomite is 0.5-1% of the amount of the slag), so as to obtain a first underflow and a first overflow liquid; subjecting the first underflow to a first continuous solid-liquid separation: the first underflow is continuously filtered in a first continuous filter 013 to obtain a magnesium-removing solution and magnesium slag, the first overflow liquid and the magnesium-removing solution are continuously fine-filtered in a first continuous fine filter 014 to obtain a magnesium-removed liquid and magnesium slag, and the two magnesium slag can be used as crystal seeds to return to the step of continuously removing magnesium.

TABLE 1

Element(s)	Li+	Mg2+	Cl-	Na+
					Concentration (g/L)	15～20	8	100	1.9

Continuously removing magnesium from the magnesium-removed liquid in a continuous lithium precipitation device 02, specifically, continuously precipitating lithium from the magnesium-removed liquid and 20-25 wt% of sodium carbonate solution in three continuous lithium precipitation tanks 025(2205 material) of a continuous lithium precipitation device 021 to obtain a second slurry; pumping the second slurry into a second continuous settling device 022 for second settling separation to obtain a second underflow and a second overflow liquid; performing second continuous solid-liquid separation on the second underflow in a second continuous filter 023 to obtain crude lithium carbonate and a lithium precipitation mother solution; performing second continuous fine filtration on the second overflow liquid and the lithium precipitation mother liquor in a second continuous fine filter 024 to obtain fine filtrate and fine filtration residues; and returning the fine filtration slag to the second sedimentation separation.

Performing continuous washing treatment on the crude lithium carbonate in a continuous washing device 03, specifically, performing continuous washing treatment on the crude lithium carbonate in three continuous washing tanks 034 of a continuous washing device 031 by using water (the temperature is 95 ℃, the volume ratio of water to the crude lithium carbonate is 7:1, and performing 3 times of counter-current washing) to obtain a third underflow and a third overflow; performing third continuous solid-liquid separation on the third bottom flow in a third continuous filter 032 to obtain a lithium carbonate solid; and (3) performing third continuous fine filtration on the third overflow liquid in a third continuous fine filter 033 to obtain fine filtered water, and returning the fine filtered water to the preparation process of the sodium carbonate solution.

And drying the lithium carbonate solid to obtain dry lithium carbonate, and packaging the dry carbonic acid to finally obtain a lithium carbonate product.

The whole lithium extraction process flow can be continuously controlled remotely through a DCS system, manual field operation is not needed, and the quality of the lithium carbonate product is randomly detected, so that the obtained lithium carbonate product is stable in quality and qualified in batch.

From the above description, it can be seen that the above-described embodiments of the present invention achieve the following technical effects:

this application adopts the lithium system of carrying of salt lake brine, and this system is including the continuous magnesium equipment that removes, the lithium equipment of sinking and continuous washing equipment that connect gradually. The integrated lithium extraction system can achieve continuous production, so that the labor intensity is obviously reduced, the product difference caused by manual control subjective distinction is reduced, the quality stability of products is improved, the product cost is reduced, and the batch qualification of lithium carbonate products is improved.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.