WO2022161492A1

WO2022161492A1 - Lithium extraction system and lithium extraction method for salt lake brine

Info

Publication number: WO2022161492A1
Application number: PCT/CN2022/075025
Authority: WO
Inventors: 周文龙; 羡鹏飞; 邱爽; 杨永亮; 徐长庆; 杜国山
Original assignee: 中国恩菲工程技术有限公司
Priority date: 2021-01-29
Filing date: 2022-01-29
Publication date: 2022-08-04
Also published as: CL2023000094A1; MX2023000395A; CN112850758A

Abstract

Provided are a lithium extraction system and a lithium extraction method for salt lake brine. The lithium extraction system comprises: a continuous magnesium removal apparatus, a continuous lithium precipitation apparatus, and a continuous washing apparatus, wherein the continuous magnesium removal apparatus is used for carrying out continuous magnesium removal treatment on lithium-rich brine by using a sodium hydroxide solution to obtain a magnesium-removed liquid and magnesium slag; the continuous lithium precipitation apparatus is connected to the continuous magnesium removal apparatus, 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 liquor; and the continuous washing apparatus is connected to the continuous lithium precipitation apparatus, and is used for continuously washing the crude lithium carbonate to obtain a lithium carbonate solid. By means of the present application, the lithium extraction system for salt lake brine is creatively used, and such an integrated lithium extraction system can realize continuous production, so as to significantly reduce labor intensity and reduce the product difference caused by subjective distinguishing of manual operation and control, thereby improving the quality stability of the product, reducing the product cost, and improving the batch qualification of the lithium carbonate product.

Description

Lithium extraction system and lithium extraction method from salt lake brine

technical field

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

Background technique

Salt lake brine is currently one of the main raw materials for lithium extraction, accounting for 66% of the world's lithium reserves. The other is granite pegmatite-type lithium ore. The global lithium-containing salt lakes are divided into three types: carbonate type, sulfate type (sodium sulfate subtype, magnesium sulfate subtype) and chloride type, with extremely uneven distribution, mainly located in the Andes Plateau of South America (Argentina, Bolivia, Chile), Qinghai-Tibet Plateau in China and Nevada in North America.

The ratio of magnesium to lithium in foreign salt lakes is low, and lithium can be extracted by precipitation, which is relatively simple in technology and stable in product quality. However, my country's lithium-rich salt lake brine has a high Mg/Li ratio, which is much higher than 8.0 in Bolivia's Uronni Salt Lake. The lithium extraction technology is difficult and the cost is high. one.

Due to the difference in composition, Mg/Li ratio, etc., different process routes such as "membrane separation method", "calcination method" and "adsorption method" are usually used to industrially produce lithium carbonate from lithium-rich brine. In addition, there are enterprises that use the gradient solar pond process + causticization process route, or use the halogen mixing method + causticization process route. At present, the domestic salt lake lithium extraction enterprises are basically "one lake and one process". Among the above-mentioned resources in China, the enterprises that realize large-scale production are mainly located in Qaidam, Qinghai, while these enterprises in the Qaidam Basin have adopted different production processes to prepare low-concentration Li ⁺ , high-concentration Mg ²⁺ initial salt lake brine "Lithium-rich brine" with high concentration of Li ⁺ and low concentration of Mg ²⁺ , and through intermittent process, the use of lithium-rich brine for intermittent production of lithium precipitation, mainly manual operation, requires a lot of human input, and different personnel, different periods The differences in subjective operations are particularly large, resulting in unstable product quality, which in turn leads to the low product quality in the Salt Lake area.

SUMMARY OF THE INVENTION

The main purpose of the present invention is to provide a system for extracting lithium from salt lake brine and a method for extracting lithium, so as to solve the problem of unstable product quality obtained by the technology of extracting lithium from salt lake in the prior art.

In order to achieve the above object, according to one aspect of the present invention, a lithium extraction system from salt lake brine is provided, the lithium extraction system includes: continuous magnesium removal equipment, continuous lithium precipitation equipment and continuous washing equipment; continuous magnesium removal equipment is used for using The sodium hydroxide solution is used to continuously remove magnesium from the lithium-rich brine to obtain a magnesium-removal liquor and magnesium slag; the continuous lithium precipitation equipment is connected with the continuous magnesium removal equipment, and is used to continuously process the magnesium-removed liquor to obtain the crude carbonic acid. Lithium and lithium precipitation mother liquor; 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 lithium carbonate solid.

Further, the above-mentioned continuous magnesium removal equipment comprises: a continuous magnesium precipitation device, a first continuous sedimentation device and a continuous solid-liquid separation device, and the continuous magnesium precipitation device is used for continuously removing magnesium from the lithium-rich brine by using a sodium hydroxide solution to obtain the first a slurry; the first continuous sedimentation device is connected with the continuous magnesium sedimentation device, and is used for the first solid-liquid separation of the first slurry to obtain the first underflow and the first overflow liquid; the continuous solid-liquid separation device is connected with the first continuous sedimentation device Connected, for the first continuous solid-liquid separation of the first underflow to obtain magnesium slag and magnesium removal 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 serially connected The continuous magnesium precipitation tank, preferably the continuous solid-liquid separation device, includes the first continuous filter and the first continuous fine filter which are connected in sequence, and the continuous magnesium precipitation device is preferably equipped with a remover feeder.

Further, the above-mentioned continuous precipitation equipment includes: a continuous precipitation device, a second continuous precipitation device and a second continuous filter, and the continuous precipitation device is used for using a sodium carbonate solution to carry out continuous precipitation treatment of the magnesium-removed liquid to obtain the first Two slurry; the second continuous sedimentation device is connected with the continuous lithium precipitation device, and is used for the second solid-liquid separation of the second slurry to obtain the second underflow and the second overflow liquid; and the second continuous filter and the second continuous sedimentation The device is connected to the second continuous solid-liquid separation for the second underflow to obtain crude lithium carbonate and precipitation lithium mother liquor; the optional second continuous fine filter is connected to the second continuous filter and the second continuous settling device respectively, using For carrying out the 3rd continuous solid-liquid separation to the second overflow liquid and the precipitation mother liquor, to obtain fine filtrate and fine filter residue; the optional second continuous fine filter and the continuous lithium precipitation device and/or the second continuous sedimentation device constitute a circulation loop For returning the fine filter residue to the continuous lithium precipitation device and/or the second continuous precipitation device; preferably the continuous lithium precipitation device includes at least one continuous lithium precipitation tank, preferably the continuous lithium precipitation device includes two to five serially connected continuous lithium precipitation tanks, Preferably, the continuous lithium precipitation device is equipped with an impurity remover feeder.

Further, the above-mentioned continuous washing equipment includes: a continuous washing device and a third continuous filter, and the continuous washing device performs continuous washing treatment on the crude lithium carbonate to obtain the third underflow and the third overflow liquid; the third continuous filter and the continuous washing The device is connected to carry out the fourth continuous solid-liquid separation on the third underflow to obtain lithium carbonate solid; the optional third continuous fine filter is connected to the inlet and outlet of the continuous washing device respectively, and is used to separate the third overflow liquid. The fifth continuous solid-liquid separation, obtaining finely filtered water and returning the finely filtered water to the preparation process of the sodium carbonate solution; preferably the continuous washing device includes at least one continuous washing tank, and preferably the continuous washing device includes two to five serial continuous washing tanks .

Further, the above-mentioned continuous magnesium precipitation tank includes an atomization device for spraying the sodium hydroxide solution into the continuous magnesium precipitation tank.

Further, the above-mentioned lithium extraction system also includes a buffer homogenizer, and the buffer homogenizer is a buffer homogenization tank or a buffer homogenization storage tank, and the buffer homogenizer is connected with the continuous magnesium removal equipment, and is used for the natural sedimentation of the lithium-rich brine. To achieve the purpose of buffer homogenization.

According to another aspect of the present invention, a method for extracting lithium from salt lake brine is provided, and the method for extracting lithium includes: step S1, using sodium hydroxide solution to continuously remove magnesium from the lithium-rich brine to obtain magnesium-removed liquor and magnesium slag; step S2, the magnesium-removed liquid is subjected to continuous lithium precipitation treatment to obtain crude lithium carbonate and a lithium precipitation mother liquor; and step S3, the crude lithium carbonate is subjected to continuous washing treatment to obtain lithium carbonate solid.

Further, the above step S1 includes: step S11, using sodium hydroxide solution to continuously remove magnesium from the lithium-rich brine to obtain a first slurry; step S12, performing a first sedimentation separation on the first slurry to obtain a first underflow and a second an overflow liquid; and in step S13, the first continuous solid-liquid separation is performed on the first underflow to obtain the magnesium slag and the magnesium-removed liquid. Preferably, step S13 includes: sequentially performing the first continuous filtration and the first continuous filtration on the first underflow. Fine filtration to obtain magnesium slag and magnesium-removing liquid, preferably adding impurity remover in the process of the first continuous filtration, preferably returning the magnesium slag to the continuous magnesium-removing treatment, preferably spraying the sodium hydroxide solution into the lithium-rich solution In the brine, preferably before step S11, buffer and homogenize the lithium-rich brine, and preferably add a flocculant and a filter aid during the first sedimentation separation process.

Further, the above-mentioned step S2 includes: step S21, using sodium carbonate solution to carry out continuous lithium precipitation treatment on the magnesium removal solution to obtain a second slurry, preferably the temperature of the continuous lithium precipitation treatment is 90～95 ℃; step S22, for the second slurry The slurry carries out the second sedimentation separation to obtain the second underflow and the second overflow liquid; and in step S23, the second underflow is carried out for the second continuous solid-liquid separation to obtain thick lithium carbonate and precipitation lithium mother liquor, and the second continuous solid-liquid separation is: Continuous filtration, optionally carrying out the second continuous fine filtration on the second overflow liquid and the precipitation lithium mother liquor to obtain fine filtrate and fine filtration residue; optionally recovering the lithium in the fine filtrate and the precipitation lithium mother liquor, The fine filter residue is returned to the second settling separation and/or the second settling separation.

Further, the above-mentioned step S3 includes: step S31, using water to continuously wash the crude lithium carbonate to obtain a third underflow and a third overflow liquid; step S32, performing a third continuous solid-liquid separation on the third underflow to obtain carbonic acid Lithium solid, preferably the third continuous solid-liquid separation is continuous filtration, optionally the third overflow liquid is subjected to the third continuous fine filtration to obtain finely filtered water, and optionally the configuration process of returning the finely filtered water to the sodium carbonate solution middle.

Further, the above-mentioned method for extracting lithium further comprises drying the lithium carbonate solid to obtain dry lithium carbonate.

By applying the technical solution of the present invention, the present application adopts a lithium extraction system from salt lake brine, and the system includes continuous magnesium removal equipment, continuous lithium precipitation equipment and continuous washing equipment connected in sequence. Such an integrated lithium extraction system can achieve continuous production, thereby significantly reducing labor intensity and reducing product differences caused by subjective differences in manual manipulation, thereby improving product quality stability, reducing product costs, and improving lithium carbonate. Lot qualification of the product.

Description of drawings

The accompanying drawings forming a part of the present application are used to provide further understanding of the present invention, and the exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the attached image:

1 shows a schematic diagram of a lithium extraction system from salt lake brine provided according to Embodiment 1 of the present invention;

Fig. 2 shows a kind of simple lithium extraction process flow chart of salt lake brine provided by the application; And

Fig. 3 shows the process flow chart of lithium extraction from salt lake brine provided in Example 1.

Wherein, the above-mentioned drawings include the following reference signs:

01, continuous magnesium removal equipment; 02, continuous lithium precipitation equipment; 03, continuous washing equipment; 04, buffer homogenizer; 011, continuous magnesium precipitation device; 012, the first continuous sedimentation device; 013, the first continuous filter; 014, the first continuous fine filter; 015, the continuous magnesium precipitation tank; 021, the continuous lithium precipitation device; 022, the second continuous sedimentation device; 023, the second continuous filter; 024, the second continuous fine filter; 025, the continuous sedimentation Lithium tank; 031, continuous washing device; 032, third continuous filter; 033, third continuous fine filter; 034, continuous washing tank.

Detailed ways

It should be noted that the embodiments in the present application and the features of the embodiments may be combined with each other in the case of no conflict. The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

As analyzed in the background art, there is a problem that the quality of products obtained by the salt lake lithium extraction technology is unstable in the prior art. To solve this problem, the present invention provides a lithium extraction system and a lithium extraction method from salt lake brine.

In a typical embodiment of the present application, a lithium extraction system from salt lake brine is provided. As shown in FIG. 1 , the lithium extraction system includes: continuous magnesium removal equipment 01, continuous lithium precipitation equipment 02, and continuous washing equipment 03; Continuous magnesium removal equipment 01 is used to continuously remove magnesium from the lithium-rich brine by using sodium hydroxide solution to obtain the magnesium-removing liquid and magnesium slag; The magnesium post-liquid is subjected to continuous lithium precipitation treatment to obtain crude lithium carbonate and a precipitation lithium mother liquor; and the continuous washing equipment 03 is connected with the continuous lithium precipitation equipment 02, and is used for continuous washing treatment of the crude lithium carbonate to obtain lithium carbonate solid.

The present application adopts a lithium extraction system from salt lake brine, and the system includes a continuous magnesium removal device 01 , a continuous lithium precipitation device 02 and a continuous washing device 03 connected in sequence. Such an integrated lithium extraction system can achieve continuous production, thereby significantly reducing labor intensity and reducing product differences caused by subjective differences in manual manipulation, thereby improving product quality stability, reducing product costs, and improving lithium carbonate. Lot qualification of the product.

In an embodiment of the present application, as shown in FIG. 1 , the above-mentioned continuous magnesium removal equipment 01 includes: a continuous magnesium precipitation device 011, a first continuous sedimentation device 012 and a continuous solid-liquid separation device; the continuous magnesium precipitation device 011 is used for The lithium-rich brine is continuously removed magnesium by using sodium hydroxide solution to obtain the first slurry; the first continuous sedimentation device 012 is connected with the continuous magnesium sedimentation device 011, and is used for the first solid-liquid separation of the first slurry to obtain the first slurry. Underflow and the first overflow liquid; and the continuous solid-liquid separation device is connected with the first continuous settling device 012 for carrying out the first continuous solid-liquid separation on the first underflow to obtain magnesium slag and magnesium-removing liquid; preferably continuous magnesium precipitation The device 011 includes at least one continuous magnesium precipitation tank 015, preferably the continuous magnesium precipitation device 011 includes two to five continuous magnesium precipitation tanks 015 in series, preferably the continuous solid-liquid separation device includes a first continuous filter 013 and a first continuous filter 013 connected in sequence. The continuous fine filter 014, preferably the continuous magnesium precipitation device 011, is equipped with an impurity remover feeder.

With reference to the schematic diagram of the lithium extraction system of salt lake brine shown in FIG. 1, it can be seen that in the above-mentioned continuous magnesium removal equipment 01, the continuous magnesium precipitation device 011, the first continuous sedimentation device 012 and the continuous solid-liquid separation device are sequentially connected in sequence. The continuous magnesium removal treatment, the first solid-liquid separation, and the first continuous solid-liquid separation are carried out continuously, which achieves the purpose of continuous magnesium removal for lithium-rich brine, avoids the influence of human factors, and improves the magnesium removal rate. quality stability. In order to facilitate adding the first slurry into the first continuous settling device 012, preferably a pump is provided between the continuous magnesium precipitation tank 015 and the first continuous settling device 012 to pump the first slurry into the first continuous settling device 012 . In order to regulate and control the sedimentation of the first slurry in the first continuous sedimentation device 012 , preferably, a temperature-controlled agitator is provided in the first continuous sedimentation device 012 . Preferably, a mechanical stirrer is provided in the continuous magnesium precipitation tank 015 to assist the efficient performance of the continuous magnesium removal process.

In order to facilitate the supply of sodium hydroxide solution, a sodium hydroxide solution supply device can be provided, which is connected with the continuous magnesium precipitation device 011 to supply sodium hydroxide solution to it.

In an embodiment of the present application, as shown in FIG. 1 , the above-mentioned continuous lithium precipitation device 02 includes: a continuous lithium precipitation device 021 , a second continuous precipitation device 022 and a second continuous filter 023 ; the continuous lithium precipitation device 021 uses In adopting sodium carbonate solution to carry out continuous lithium precipitation treatment on the magnesium-removed liquid to obtain the second slurry; the second continuous sedimentation device 022 is connected with the continuous lithium precipitation device 021, and is used to carry out the second solid-liquid separation on the second slurry to obtain the second slurry. Two underflows and the second overflow liquid; and the second continuous filter 023 is connected with the second continuous settling device 022 for carrying out the second continuous solid-liquid separation on the second underflow to obtain crude lithium carbonate and precipitation lithium mother liquor; optional The second continuous fine filter 024 is connected with the second continuous filter 023 and the second continuous sedimentation device 022 respectively, for carrying out the third continuous solid-liquid separation to the second overflow liquid and the precipitation mother liquor, to obtain fine filtrate and fine filter residue , the optional second continuous fine filter 024 and the continuous lithium precipitation device 021 and/or the second continuous sedimentation device 022 constitute 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 precipitation device 021 includes at least one continuous lithium precipitation tank 025. Preferably, the continuous lithium precipitation device 021 includes two to five continuous lithium precipitation tanks 025 in series. Preferably, the continuous lithium precipitation device 021 is equipped with an impurity remover feeder.

Combined with the schematic diagram of the lithium extraction system of salt lake brine shown in Figure 1, it can be seen that the first continuous fine filter 014 and the continuous lithium precipitation device 021, the second continuous sedimentation device 022 and the second continuous filter 023 in the continuous magnesium removal equipment 01 are By connecting in sequence, the magnesium removal liquid obtained in the continuous magnesium removal equipment 01 can be subjected to continuous lithium precipitation treatment to obtain crude lithium carbonate, and the influence of human factors is avoided, and the quality stability of the crude lithium carbonate is improved. Among them, two to five continuous lithium precipitation tanks 025 in series can more fully carry out continuous lithium precipitation treatment on the magnesium removal liquid, and can increase the processing capacity of the magnesium removal liquid according to actual needs. The configuration of the impurity remover feeder on the continuous lithium precipitation device 021 can selectively add impurity remover according to the actual situation of the continuous lithium precipitation treatment process, so as to further improve the effect of the continuous lithium precipitation treatment. Preferably, a pump is provided between the continuous lithium precipitation tank 025 and the second continuous settling device 022 so as to pump the second slurry into the second continuous settling device 022 . Preferably, a temperature-controlled agitator is provided in the second continuous settling device 022 to regulate and control the second solid-liquid separation process. Preferably, a mechanical stirrer is provided in the continuous magnesium precipitation tank 015 to assist the efficient progress of the continuous lithium precipitation treatment.

In order to facilitate the provision of sodium carbonate solution, a sodium carbonate solution supply device may be provided, which is connected to the continuous lithium precipitation device 021 to supply sodium carbonate solution to it.

In an embodiment of the present application, as shown in FIG. 1 , the above-mentioned continuous washing equipment 03 includes: a continuous washing device 031 and a third continuous filter 032; the continuous washing device 031 continuously washes the crude lithium carbonate to obtain the first Three underflows and the third overflow liquid; the third continuous filter 032 is connected to the continuous washing device 031, and is used for the fourth continuous solid-liquid separation of the third underflow to obtain lithium carbonate solid; the optional third continuous fine filter 033 It is connected with the inlet and outlet of the continuous washing device 031 respectively, and is used to carry out the fifth continuous solid-liquid separation on the third overflow liquid to obtain the finely filtered water and return the finely filtered water to the preparation process of the sodium carbonate solution; preferably the continuous washing device 031 includes at least one continuous washing tank 034, preferably the continuous washing device 031 includes two to five continuous washing tanks 034 in series.

Combined with the schematic diagram of the lithium extraction system of salt lake brine shown in FIG. 1, it can be seen that the second continuous filter 023 of the continuous lithium precipitation equipment 02 is connected with the continuous washing device 031 of the continuous washing equipment 03, and the continuous washing device 031 and the third continuous washing device 031. The sequential connection of the filters 032 realizes the continuous washing process of the crude lithium carbonate, obtains the lithium carbonate solid, and reduces the difference of the lithium carbonate solid caused by the subjective difference of manual manipulation.

In order to further make the sodium hydroxide solution contact with the lithium-rich brine more fully, thereby improving the efficiency of the continuous magnesium removal treatment, preferably the above-mentioned continuous magnesium precipitation tank 015 includes an atomizing device for spraying the sodium hydroxide solution into the continuous magnesium precipitation. Slot 015.

In an embodiment of the present application, as shown in FIG. 1 , the above lithium extraction system further includes a buffer homogenizer 04, which is a buffer homogenization tank or a buffer homogenization storage tank, and the buffer homogenizer 04 It is connected with the continuous magnesium removal equipment 01, and is used for the natural sedimentation of the lithium-rich brine to achieve the purpose of buffering and homogenization.

The buffer homogenizer 04 is used to store lithium-rich brine (production of lithium salt raw materials, Li ⁺ >15g/L). The storage period or storage capacity can be appropriately extended according to the stable supply capacity of lithium-rich brine raw materials and investment conditions. In order to further avoid secondary pollution to the lithium-rich brine, preferably the buffer homogenizer 04 is a closed buffer tank or a closed buffer storage tank; in order to prolong the residence time of the lithium-rich brine, it is preferred to set a diversion weir in the buffer homogenizer, To achieve the purpose of natural sedimentation of trace solids, homogenization and stabilization of the latter stage production; further, preferably, the bottom of the buffer homogenizer has a certain slope, so as to regularly clean the trace solids in the lithium-rich brine.

In another typical embodiment of the present application, a method for extracting lithium from salt lake brine is provided. Referring to FIG. 2 or FIG. 3 , the method for extracting lithium includes: step S1 , using sodium hydroxide solution to extract lithium-rich brine Continuous magnesium removal treatment to obtain magnesium-removed liquid and magnesium slag; step S2, continuous lithium precipitation treatment is performed on the magnesium-removed liquid to obtain crude lithium carbonate and precipitation lithium mother liquor; and step S3, the crude lithium carbonate is subjected to continuous washing treatment, Lithium carbonate solid was obtained.

The present application adopts a method for extracting lithium from salt lake brine, and the method for extracting lithium includes continuous magnesium removal treatment, continuous lithium precipitation treatment, and continuous washing treatment performed on the lithium-rich brine in sequence, so as to realize the continuous production of lithium extraction from salt lake brine, and thus significantly The labor intensity is reduced, and the product difference caused by the subjective difference of manual manipulation is reduced, thereby improving the quality stability of the product, reducing the product cost, and improving the batch qualification of lithium carbonate products.

In an embodiment of the present application, as shown in FIG. 3 , the above step S1 includes: step S11 , using sodium hydroxide solution to continuously remove magnesium from the lithium-rich brine to obtain a first slurry; step S12 , removing the first slurry The slurry is subjected to the first sedimentation separation to obtain the first underflow and the first overflow liquid; and in step S13, the first underflow is subjected to the first continuous solid-liquid separation to obtain the magnesium slag and the magnesium-removed liquid. Preferably, the step S13 includes: The first continuous filtration and the first continuous fine filtration are carried out in turn in an underflow, to obtain magnesium slag and a magnesium-removing liquid, preferably adding an impurity-removing agent during the first continuous filtration, preferably returning the magnesium slag to the continuous magnesium-removing treatment, preferably The sodium hydroxide solution is sprayed into the lithium-rich brine, preferably before step S11, the lithium-rich brine is buffered and homogenized, and flocculants and filter aids are preferably added during the first sedimentation and separation process.

The above-mentioned step S1 of the present application can realize the continuous magnesium removal treatment of the lithium-rich brine, and obtain the magnesium removal liquid with stable quality. Among them, the above-mentioned buffering and homogenization treatment of the lithium-rich brine can make the trace solids in the lithium-rich brine settle naturally, so as to achieve the purpose of homogenizing and stabilizing the production in the later stage. In the process of the first solid-liquid separation, a flocculant (such as 100-250 mg/kg anionic polyacrylamide) and a filter aid (such as diatomaceous earth) are added, and it is preferred to add impurity removal in the process of the first continuous solid-liquid separation It is helpful to reduce the impurity content in the liquid after magnesium removal. It is preferable to return the magnesium slag to the continuous magnesium removal treatment as a crystal seed, which helps to make the magnesium hydroxide precipitate on the surface of the crystal seed to grow up and form agglomeration with a certain particle size. Magnesium hydroxide slag. The above-mentioned sodium hydroxide solution (30-40wt%) of the present application is preferably sprayed into the lithium-rich brine in a mist-like controllable flow manner, so that the sodium hydroxide solution and the lithium-rich brine can be mixed more fully, thereby improving the continuous removal of magnesium. processing efficiency. Of course, those skilled in the art can also refer to the prior art for the process of the continuous magnesium removal treatment for the lithium-rich brine, which will not be repeated here.

In an embodiment of the present application, as shown in FIG. 3 , the above-mentioned step S2 includes: step S21 , using sodium carbonate solution to carry out continuous lithium precipitation treatment on the magnesium removal solution to obtain a second slurry; The temperature is 90 to 95°C; step S22, the second sedimentation separation is performed on the second slurry to obtain a second underflow and a second overflow liquid; and step S23, the second underflow is subjected to a second continuous solid-liquid separation to obtain crude carbonic acid Lithium and precipitation lithium mother liquor, the second continuous solid-liquid separation is continuous filtration, and optionally the second overflow liquid and precipitation lithium mother liquor are subjected to second continuous fine filtration to obtain fine filtrate and fine filtration residue; The lithium in the precipitation mother liquor is recovered, and the fine filter residue is optionally returned to the second sedimentation separation and/or the second sedimentation separation.

Referring to the process flow chart of lithium extraction from salt lake brine shown in FIG. 3 , it can be seen that the above-mentioned step S2 can achieve the purpose of obtaining crude lithium carbonate by continuous lithium precipitation treatment of the liquid after magnesium removal. And in order to improve the precipitation efficiency of lithium carbonate, the temperature of the continuous lithium precipitation treatment is preferably 90-95 °C, and returning the fine filter residue for reuse can further improve the utilization rate of waste and reduce the cost. The above-mentioned sodium carbonate solution of the present application performs continuous lithium precipitation treatment on the magnesium-removal liquid with reference to the prior art, which will not be repeated here.

In order to further improve the purity of lithium carbonate, as shown in Figure 3, preferably the above step S3 includes: step S31, using water to continuously wash the crude lithium carbonate to obtain a third underflow and a third overflow; step S32, the third The third continuous solid-liquid separation is carried out in the three bottom streams to obtain lithium carbonate solid, preferably the third continuous solid-liquid separation is continuous filtration, and optionally the third overflow liquid is subjected to the third continuous fine filtration to obtain finely filtered water, and optionally In the configuration process of returning the finely filtered water to the sodium carbonate solution, thereby realizing the reuse of the finely filtered water and the further recovery of lithium, reducing the water consumption and reducing the cost, wherein, in order to balance the washing effect and the water consumption, preferably water and crude carbonic acid The liquid-solid ratio of lithium is 3 to 7:1.

In an embodiment of the present application, as shown in FIG. 3 , the above-mentioned method for extracting lithium further includes drying the solid lithium carbonate to obtain dry lithium carbonate; and packaging the dried lithium carbonate to obtain a lithium carbonate product.

Drying and packaging the lithium carbonate solid obtained after washing and purification is beneficial to avoid product differences caused by manual manipulation and subjective distinction from beginning to end, thereby improving the quality stability of the product and improving the batch qualification of lithium carbonate products.

The beneficial effects of the present application will be described below with reference to specific embodiments.

The following examples refer to using the lithium extraction system shown in FIG. 1 and the lithium extraction process flow of the salt lake brine shown in FIG. 3 to extract lithium from the lithium-rich brine.

Example 1

In the buffer homogenizer 04, the lithium-rich brine (Li ⁺ >15g/L) is naturally settled and homogenized and stored for a certain period of time. The composition of the lithium-rich brine is shown in Table 1. The lithium-rich brine is stored in a continuous magnesium removal equipment In 01, continuous magnesium removal treatment is carried out, specifically, the lithium-rich brine and 30wt% sodium hydroxide solution (sprayed into the continuous magnesium precipitation tank in a mist controllable flow mode) after the buffering and homogenization treatment are placed in a continuous magnesium precipitation device. Carry out continuous magnesium removal treatment (temperature is 95 ℃) in three continuous magnesium precipitation tanks 015 of 011, obtain the first slurry; The first slurry is pumped into the first continuous settling device 012 to carry out the first settling separation (adding 200mg/kg anionic polyacrylamide and diatomaceous earth, the amount of diatomite added is 0.5-1% of the amount of slag) to obtain the first underflow and the first overflow liquid; the first continuous solid-liquid separation is performed on the first underflow: first The first underflow is continuously filtered in the first continuous filter 013 to obtain a magnesium removal solution and magnesium slag, and then the first overflow liquid and the magnesium removal solution are continuously filtered in the first continuous fine filter 014 to obtain a magnesium removal solution. Magnesium post-liquid and magnesium slag, the above-mentioned two parts of magnesium slag can be used as the crystal seed returning step to continuously remove magnesium.

Table 1

元素element	Li ⁺ Li ⁺	Mg ²⁺ Mg ²⁺	Cl ^- Cl ^-	Na ⁺ Na ⁺
浓度(g/L)Concentration (g/L)	15～2015～20	88	100100	1.91.9

In the continuous lithium precipitation equipment 02, the magnesium-removed liquid is subjected to continuous magnesium removal treatment. Specifically, the above-mentioned magnesium-removed liquid and 20-25wt% sodium carbonate solution are placed in three continuous lithium precipitation tanks 025 of the continuous lithium precipitation device 021. (2205 material), carry out continuous lithium precipitation treatment to obtain the second slurry; pump the second slurry into the second continuous sedimentation device 022 to carry out the second sedimentation separation to obtain the second underflow and the second overflow liquid; in the second continuous The second continuous solid-liquid separation is carried out to the second underflow in the filter 023 to obtain thick lithium carbonate and the precipitation lithium mother liquor; in the second continuous fine filter 024, the second continuous fine filtration is carried out to the second overflow liquid and the precipitation lithium mother liquor, The fine filtrate and fine filter residue are obtained; the fine filter residue is returned to the second sedimentation separation.

In the continuous washing device 03, the crude lithium carbonate is continuously washed, and specifically, the above-mentioned crude lithium carbonate is subjected to continuous washing in the three continuous washing tanks 034 of the continuous washing device 031 by using water (the temperature is 95 ° C, water and The volume ratio of thick lithium carbonate is 7:1, 3 countercurrent washings), obtains the 3rd underflow and the 3rd overflow liquid; The 3rd underflow is carried out the 3rd continuous solid-liquid separation in the 3rd continuous filter 032, obtains carbonic acid Lithium solid; carry out the third continuous fine filtration of the third overflow liquid in the third continuous fine filter 033 to obtain fine filtered water, and return the fine filtered water to the preparation process of the sodium carbonate solution.

The lithium carbonate solid is dried to obtain dry lithium carbonate, and the dried carbonic acid is packaged to finally obtain a lithium carbonate product.

The continuation of the whole process of lithium extraction above can be realized by remote control through DCS system without manual on-site operation, and through random inspection of the quality of lithium carbonate products, it is found that the quality of the lithium carbonate products obtained above is stable and the batches are qualified.

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

The present application adopts a lithium extraction system from salt lake brine, which includes continuous magnesium removal equipment, continuous lithium precipitation equipment and continuous washing equipment connected in sequence. Such an integrated lithium extraction system can achieve continuous production, thereby significantly reducing labor intensity and reducing product differences caused by subjective differences in manual manipulation, thereby improving product quality stability, reducing product costs, and improving lithium carbonate. Lot qualification of the product.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

A lithium extraction system for salt lake brine, characterized in that the lithium extraction system comprises:

Continuous magnesium removal equipment (01), for continuously removing magnesium from lithium-rich brine by using sodium hydroxide solution to obtain magnesium removal liquid and magnesium slag;

Continuous lithium precipitation equipment (02), connected with the continuous magnesium removal equipment (01), for carrying out the continuous lithium precipitation treatment with the magnesium removal post-liquid, to obtain thick lithium carbonate and precipitation lithium mother liquor; And

A continuous washing device (03), connected with the continuous lithium precipitation device (02), is used for continuously washing the crude lithium carbonate to obtain a lithium carbonate solid.
The lithium extraction system according to claim 1, wherein the continuous magnesium removal device (01) comprises:

A continuous magnesium precipitation device (011) is used for continuously removing magnesium from the lithium-rich brine by using the sodium hydroxide solution to obtain a first slurry;

a first continuous settling device (012), connected with the continuous magnesium precipitation device (011), for performing a first solid-liquid separation on the first slurry to obtain a first underflow and a first overflow; and

A continuous solid-liquid separation device, connected with the first continuous settling device (012), for performing the 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) includes at least one continuous magnesium precipitation tank (015), preferably the continuous magnesium precipitation device (011) includes two to five continuous magnesium precipitation tanks (015) in series, preferably all The continuous solid-liquid separation device includes a first continuous filter (013) and a first continuous fine filter (014) that are connected in sequence, and preferably, the continuous magnesium precipitation device (011) is equipped with an impurity remover feeder.
The lithium extraction system according to claim 1 or 2, wherein the continuous lithium deposition equipment (02) comprises:

The continuous lithium precipitation device (021) is used to carry out the continuous lithium precipitation treatment on the magnesium-removed liquid by using a sodium carbonate solution to obtain a second slurry;

A second continuous sedimentation device (022), connected to the continuous lithium precipitation device (021), is used to perform a second solid-liquid separation on the second slurry to obtain a second underflow and a second overflow; and

The second continuous filter (023) is connected with the second continuous sedimentation device (022), and is used for the second continuous solid-liquid separation of the second underflow to obtain the crude lithium carbonate and the precipitation lithium mother liquor ;

An optional second continuous fine filter (024) is connected to the second continuous filter (023) and the second continuous sedimentation device (022), respectively, and is used for filtering the second overflow liquid and the Precipitating lithium mother liquor carries out the 3rd continuous solid-liquid separation, obtains fine filtrate and fine filter residue, optional described second continuous fine filter (024) and described continuous lithium precipitation device (021) and/or described second continuous sedimentation The device (022) constitutes 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 precipitation device (021) comprises at least one continuous lithium precipitation tank (025), preferably the continuous lithium precipitation device (021) comprises two to five continuous lithium precipitation tanks (025) in series, preferably all The continuous lithium precipitation device (021) is configured with an impurity remover feeder.
The lithium extraction system according to any one of claims 1 to 3, wherein the continuous washing device (03) comprises:

Continuous washing device (031), carrying out the continuous washing process on the crude lithium carbonate to obtain the third underflow and the third overflow;

A third continuous filter (032), connected to the continuous washing device (031), is used for performing the fourth continuous solid-liquid separation on the third underflow to obtain the lithium carbonate solid;

The optional third continuous fine filter (033) is connected to the inlet and the outlet of the continuous washing device (031) respectively, and is used to carry out the fifth continuous solid-liquid separation on the third overflow liquid to obtain finely filtered water and returning the finely filtered water to the configuration process of the sodium carbonate solution;

Preferably the continuous washing device (031) comprises at least one continuous washing tank (034), preferably the continuous washing device (031) comprises two to five continuous washing tanks (034) in series.
The lithium extraction system according to claim 2, characterized in that, the continuous magnesium precipitation tank (015) comprises an atomizing device for spraying the sodium hydroxide solution into the continuous magnesium precipitation tank (015).
The lithium extraction system according to claim 1, characterized in that, the lithium extraction system further comprises a buffer homogenizer (04), and the buffer homogenizer (04) is a buffer homogenization tank or a buffer homogenization storage tank , the buffer homogenizer (04) is connected with the continuous magnesium removal device (01), and is used for the natural sedimentation of the lithium-rich brine to achieve the purpose of buffer homogenization.
A method for extracting lithium from salt lake brine, wherein the method for extracting lithium comprises:

Step S1, using sodium hydroxide solution to continuously remove magnesium from the lithium-rich brine to obtain magnesium-removed liquor and magnesium slag;

Step S2, carry out continuous lithium precipitation treatment to the described magnesium-removal post-liquid, obtain thick lithium carbonate and precipitation lithium mother liquor; And

In step S3, the crude lithium carbonate is continuously washed to obtain solid lithium carbonate.
The method for extracting lithium according to claim 7, wherein the step S1 comprises:

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

Step S12, carrying out the first sedimentation separation of the first slurry to obtain a first underflow and a first overflow; and

In step S13, the first continuous solid-liquid separation is performed on the first underflow to obtain the magnesium slag and the magnesium-removal liquid. Preferably, the step S13 includes:

The first continuous filtration and the first continuous fine filtration are successively performed on the first underflow to obtain the magnesium slag and the magnesium-removed liquid,

Preferably, an impurity remover is added in the process of the first continuous filtration, the magnesium slag is preferably returned to the continuous magnesium removal treatment, and the sodium hydroxide solution is preferably sprayed into the lithium-rich brine by spraying ,

Preferably, before the step S11, the lithium-rich brine is subjected to a buffering and homogenization treatment, and a flocculant and a filter aid are preferably added during the first sedimentation separation process.
The method for extracting lithium according to claim 7 or 8, wherein the step S2 comprises:

Step S21, using sodium carbonate solution to carry out the continuous lithium precipitation treatment on the magnesium-removed liquid to obtain a second slurry, preferably the temperature of the continuous lithium precipitation treatment is 90-95°C;

Step S22, performing a second sedimentation separation on the second slurry to obtain a second underflow and a second overflow; and

In step S23, the second continuous solid-liquid separation is carried out on the second underflow to obtain the thick lithium carbonate and the precipitation lithium mother liquor,

The second continuous solid-liquid separation is continuous filtration,

Optionally carry out the second continuous fine filtration with the second overflow liquid and the lithium precipitation mother liquor to obtain fine filtrate and fine filtration residue;

Optionally, the fine filtrate and the lithium in the lithium precipitation mother liquor are recovered, and the fine filter residue is optionally returned to the second sedimentation separation and/or the second sedimentation separation.
The method for extracting lithium according to any one of claims 7 to 9, wherein the step S3 comprises:

Step S31, using water to carry out the continuous washing process on the crude lithium carbonate to obtain a third underflow and a third overflow;

In step S32, the third continuous solid-liquid separation is performed on the third underflow to obtain the lithium carbonate solid,

Preferably, the third continuous solid-liquid separation is continuous filtration,

Optionally, the third overflow liquid is carried out the third continuous fine filtration to obtain fine filtered water, and

Optionally, the finely filtered water is returned to the configuration process of the sodium carbonate solution.
The method for extracting lithium according to any one of claims 7 to 10, wherein the method for extracting lithium further comprises:

The solid lithium carbonate is dried to obtain dry lithium carbonate.