阅读说明：本技术 洗涤碳酸锂的方法 (Method for washing lithium carbonate ) 是由 李健 王洪 陈文学 高松 陈传勋 李继伟 东宝山 王启豪 于 2019-12-04 设计创作，主要内容包括：本发明涉及洗涤碳酸锂的方法,所述方法包括如下步骤：(1)将碳酸锂浆料进行过滤；(2)通入去离子水,然后将所得的全部碳酸锂混合物滤饼加入到所述去离子水中；(3)然后进行搅拌洗涤得到碳酸锂浆料,同时通入净化后的蒸汽；然后将所述碳酸锂浆料进行粉碎,并将粉碎后的碳酸锂浆料循环返回再进行搅拌洗涤,由此连续并循环进行粉碎和搅拌洗涤；(4)任选地,使所得的全部碳酸锂浆料再进行一次或多次的上述步骤(1)、(2)和(3)；(5)然后将所得的全部碳酸锂浆料进行离心洗涤分离。本发明的方法通过深度洗涤,显著降低了转化沉锂后的物料中Na<Sup>+</Sup>、K<Sup>+</Sup>等可溶性杂质的含量,从而制得纯度更高的碳酸锂产物。(The invention relates to a method for washing lithium carbonate, which comprises the following steps of (1) filtering lithium carbonate slurry, (2) introducing deionized water, then adding all lithium carbonate mixture filter cakes into the deionized water, (3) stirring and washing to obtain lithium carbonate slurry, and introducing purified steam, then crushing the lithium carbonate slurry, and recycling the crushed lithium carbonate slurry for stirring and washing, thereby continuously and circularly performing crushing and stirring and washing, (4) optionally, performing times or more times on all the lithium carbonate slurry, namely (1), (2) and (3), and (5) then performing centrifugal washing and separation on all the lithium carbonate slurry + 、K + And the content of soluble impurities is equal, so that the lithium carbonate product with higher purity is prepared.)

A method of washing lithium carbonate of , said method comprising the steps of:

(1) conveying lithium carbonate slurry generated in a lithium deposition working section of a lithium carbonate production process to a level 1 filtering mechanism for filtering to obtain a lithium carbonate mixture filter cake;

(2) introducing deionized water into the 1 st-stage slurry washing mechanism, and then adding all the obtained lithium carbonate mixture filter cakes into the deionized water;

(3) then stirring and washing the lithium carbonate mixture filter cake in the 1 st-stage slurry washing mechanism to obtain lithium carbonate slurry; simultaneously introducing purified steam into the lithium carbonate slurry to keep the obtained lithium carbonate slurry in a constant temperature range,

then conveying the lithium carbonate slurry into a 1 st-stage crushing mechanism for crushing to obtain crushed lithium carbonate slurry, and circularly returning the crushed lithium carbonate slurry to the 1 st-stage pulp washing mechanism for stirring and washing, thereby continuously and circularly crushing and stirring and washing;

(4) optionally, the whole lithium carbonate slurry obtained is sent to the filtering mechanism, the slurry washing mechanism and the crushing mechanism of the next or more stages, so that the steps (1), (2) and (3) are carried out times or more,

wherein the lower -grade or multi-grade filtering mechanism, the pulp washing mechanism and the crushing mechanism are respectively the same as the 1 st-grade filtering mechanism, the 1 st-grade pulp washing mechanism and the 1 st-grade crushing mechanism;

(5) then conveying all the obtained lithium carbonate slurry to a 1 st-level centrifugal washing and separating system for th centrifugal separation, centrifugal washing and second centrifugal separation to obtain a lithium carbonate semi-dry solid;

(6) optionally, feeding all the obtained lithium carbonate semi-dry solid into a lower -stage or multi-stage centrifugal washing separation system, wherein only centrifugal washing and second centrifugal separation are carried out in each -stage of the lower -stage or multi-stage centrifugal washing separation system,

wherein the lower stage or multi-stage centrifugal washing separation system is the same as the stage 1 centrifugal washing separation system.

2. The method of claim 1, wherein in step (2), the temperature of the deionized water is 80-90 ℃.

3. The process of any of claims 1-2 wherein the lithium carbonate slurry is heated in step (3) with steam at 150-180 ℃ to maintain the lithium carbonate slurry within a constant temperature range of 80-90 ℃.

4. The process of any of claims 1-3, wherein in step (3), the purified steam enters from the bottom of the stage 1 pulp washing mechanism and is in direct contact with the lithium carbonate slurry.

5. The method of claim 1, wherein in step (3), the purified steam is obtained by: the steam is subjected to a filtration process and a water-vapor separation process.

6. The method of claim 1, wherein in step (3), the lithium carbonate slurry has a particle size D after being pulverized₅₀Is 20-30 μm.

7. The method according to claim 1, wherein in step (3), the total time of the agitation washing is 15 to 30 minutes.

8. The process according to claim 1, wherein in step (4), the entire lithium carbonate slurry obtained is subjected to the above steps (1), (2) and (3) twice.

9. The method of claim 1, wherein

In the step (1), the 1 st stage filtering mechanism is a plate-and-frame filter press,

in the step (2), the 1 st-stage pulp washing mechanism comprises a washing pulp tank and a stirring member, the 1 st-stage crushing mechanism is a high-speed shear pump,

in step (5), the stage 1 centrifugal washing separation system comprises a punching bag discharge centrifuge.

Technical Field

The invention relates to the production of lithium carbonate, in particular to methods for washing lithium carbonate.

Background

Lithium (Li) is silvery white metal elements, is a metal with the smallest density, has physicochemical characteristics of high specific heat, high conductivity, strong chemical activity and the like, has applications, can be used in a plurality of fields such as batteries, aerospace, nuclear fusion power stations, metallurgy, ceramics, glass, lubricating grease, medicines and the like, and is inorganic compounds which are colorless monoclinic crystal system crystals or white powder, is a common lithium ion battery raw material and can be used for preparing various lithium compounds, lithium metal and isotopes thereof or directly used for preparing ceramics, medicines, catalysts and the like.

In the process of producing the lithium carbonate, due to the characteristics of easy agglomeration and adhesion of the lithium carbonate, part of impurities are wrapped and adhered in materials and are difficult to deeply remove, and the purification process of the lithium carbonate has high technical difficulty and high cost.

There is a great need for new methods of washing lithium carbonate to effectively remove impurities.

Disclosure of Invention

The invention aims to solve the technical problems and provide methods for deeply washing lithium carbonate, which can be applied to the lithium carbonate production process and can effectively remove impurities.

Specifically, the invention relates to methods for washing lithium carbonate, which comprises the following steps:

(1) conveying lithium carbonate slurry generated in a lithium deposition working section of a lithium carbonate production process to a level 1 filtering mechanism for filtering to obtain a lithium carbonate mixture filter cake;

(2) introducing deionized water into the 1 st-stage slurry washing mechanism, and then adding all the obtained lithium carbonate mixture filter cakes into the deionized water;

(3) then stirring and washing the lithium carbonate mixture filter cake in the 1 st-stage slurry washing mechanism to obtain lithium carbonate slurry; simultaneously introducing purified steam into the lithium carbonate slurry to keep the obtained lithium carbonate slurry in a constant temperature range,

then conveying the lithium carbonate slurry into a 1 st-stage crushing mechanism for crushing to obtain crushed lithium carbonate slurry, and circularly returning the crushed lithium carbonate slurry to the 1 st-stage pulp washing mechanism for stirring and washing, thereby continuously and circularly crushing and stirring and washing;

(4) optionally, the whole lithium carbonate slurry obtained is sent to the filtering mechanism, the slurry washing mechanism and the crushing mechanism of the next or more stages, so that the steps (1), (2) and (3) are carried out times or more,

wherein the lower -grade or multi-grade filtering mechanism, the pulp washing mechanism and the crushing mechanism are respectively the same as the 1 st-grade filtering mechanism, the 1 st-grade pulp washing mechanism and the 1 st-grade crushing mechanism;

(5) then conveying all the obtained lithium carbonate slurry to a 1 st-level centrifugal washing and separating system for th centrifugal separation, centrifugal washing and second centrifugal separation to obtain a lithium carbonate semi-dry solid;

(6) optionally, feeding all the obtained lithium carbonate semi-dry solid into a lower -stage or multi-stage centrifugal washing separation system, wherein only centrifugal washing and second centrifugal separation are carried out in each -stage of the lower -stage or multi-stage centrifugal washing separation system,

wherein the lower stage or multi-stage centrifugal washing separation system is the same as the stage 1 centrifugal washing separation system.

In embodiments, in step (2), the temperature of the deionized water is 80-90 ℃.

In embodiments, in step (3), the lithium carbonate slurry was heated with steam at 150-.

In embodiments, in step (3), the purified steam enters from the bottom of the 1 st stage pulp washing mechanism and directly contacts with the lithium carbonate slurry.

In embodiments, in step (3), the purified steam is obtained by subjecting steam to a filtration process and a moisture separation process.

In embodiments, in step (3), the lithium carbonate slurry has a particle size D after being pulverized₅₀Is 20-30 μm.

In embodiments, in step (3), the total time of the agitated washing is 15 to 30 minutes.

In embodiments, in step (4), the entire lithium carbonate slurry obtained was subjected to the above steps (1), (2) and (3) twice.

In the preferred embodiments, the first and second,

in the step (1), the 1 st stage filtering mechanism is a plate-and-frame filter press,

in the step (2), the 1 st-stage pulp washing mechanism comprises a washing pulp tank and a stirring member, the 1 st-stage crushing mechanism is a high-speed shear pump,

in step (5), the stage 1 centrifugal washing separation system comprises a punching bag discharge centrifuge.

Advantageous effects

The method of the invention significantly reduces Na in the material after the conversion and lithium precipitation through deep washing⁺、K⁺And the content of soluble impurities is equal, so that the lithium carbonate product with higher purity is prepared. The lithium carbonate product can enter a subsequent section for other treatment.

The method of the invention better solves the problem of Na in the process of producing lithium carbonate⁺、K⁺The problem that impurities are high in content and difficult to deeply remove is a key process method for enabling the quality of lithium carbonate to reach a battery level, the purity of a lithium carbonate product can be greatly improved, and the quality uniformity is kept.

Drawings

Fig. 1 is a process flow diagram of a method of washing lithium carbonate in accordance with embodiments of the present invention.

Fig. 2 is a process flow diagram of a method of washing lithium carbonate in accordance with another embodiments of the invention.

Reference numerals

1: conversion slurry

2: filtrate

3: deionized water

4: steam generating device

5: semi-finished product of lithium carbonate

100: filtering, pulp washing and crushing system

101: filtering mechanism

102: filtering and recycling mechanism

103: slurry washing mechanism

104: steam filtering mechanism

105: crushing mechanism

106: conveying mechanism

11 th th valve

12 second valve

200: centrifugal washing and separating system

201: centrifugal washing and separating mechanism

202 th recovery mechanism

203: second recovery mechanism

Detailed Description

The method for deeply washing lithium carbonate according to the present invention is described in detail below with reference to the accompanying drawings. The terms or words used in the present specification and claims should not be construed restrictively as general or dictionary definitions, and should be construed as meanings and concepts corresponding to technical ideas of the present invention on the basis of the principle that the inventor can appropriately define concepts of the terms to describe the invention in the best possible manner.

1. Method for washing lithium carbonate

The invention relates to methods for washing lithium carbonate, which adopts batch treatment or batch treatment and mainly comprises two processes of filtering, pulp washing, crushing and centrifugal washing and separation, wherein each process comprises a plurality of steps, and the method is as follows.

() filtration, pulp washing and pulverization process

(1) Preliminary filtration

In order to reduce the pressure of the subsequent washing process, quantitative lithium carbonate slurry generated from the conversion lithium deposition section in the lithium carbonate production process is conveyed to a filtering mechanism for primary filtering, and after water and other soluble impurities are filtered out, a lithium carbonate mixture filter cake containing quantitative water and impurities is obtained.

(2) Deionized water is introduced and filter cake is added

proportions of deionized water were passed through the slurry wash mechanism and the entire resultant cake of lithium carbonate mixture was added to the deionized water.

In order to increase the solubility of soluble impurities during the subsequent stirring washing, the impurities are easily dissolved in deionized water and then filtered, and the temperature of the deionized water can be kept between 70 and 95 ℃, and is preferably between 80 and 90 ℃.

(3) Stirring, washing and pulverizing

And stirring and washing (slurry washing) the lithium carbonate mixture filter cake and deionized water in a slurry washing mechanism to prepare slurry, so as to obtain homogeneous lithium carbonate slurry.

In order to keep the temperature of the lithium carbonate slurry within a relatively constant temperature range (for example, 80-90 ℃) so as to be beneficial to controlling the quality stability of the finished product after impurity removal, the slurry is heated by purified steam while stirring and washing, and the steam temperature can be 150-180 ℃.

Steam enters from the bottom of the slurry washing tank and then directly contacts with the slurry, and the steam has longer contact time with the lithium carbonate slurry in the rising process, so that the heating efficiency is high; meanwhile, the lithium carbonate slurry is driven to turn over in the rising process, the longitudinal stirring effect is achieved, the circumferential stirring of the stirring member is combined, the washing efficiency is higher, and the effect is better.

Before entering, the steam is filtered to remove impurities in the steam through a separately arranged steam filtering mechanism and is subjected to water-vapor separation treatment, so that the cleanliness of the steam is ensured, and the impurities in a steam pipeline are prevented from being introduced into the material.

Then, the user can use the device to perform the operation,and conveying lithium carbonate slurry containing lithium carbonate and deionized water from the slurry washing mechanism to the crushing mechanism. The lithium carbonate slurry is fully crushed under the action of strong shearing force of the crushing mechanism, so that false packages formed by lithium carbonate peritectic crystals and lithium carbonate and air are broken, impurities are prevented from being packaged in the lithium carbonate peritectic crystals and the air false packages or being adhered to the lithium carbonate peritectic crystals and the air false packages, and soluble impurities are more easily in full contact with deionized water and are dissolved in the deionized water. The particle diameter D of the crushed lithium carbonate slurry₅₀May be 20-30 μm.

In order to enhance the washing effect, the crushed slurry enters the slurry washing mechanism again to be stirred and washed so as to better dissolve soluble impurities.

The above-mentioned pulverization and agitation washing are continuously and cyclically carried out until the corresponding process standard is reached. The total treatment time for the agitated washing may be 15-30 minutes.

(4) Multistage filtration, agitation washing and pulverization

Optionally, for deeper washing of the lithium carbonate slurry, it may be passed through times or more of the above steps (1), (2) and (3) which are relatively independent and connected in series to reach the corresponding process index, and then enter the following centrifugal washing separation process.

(II) centrifugal washing separation process

(1) centrifugal separation

And (3) all the lithium carbonate slurry which finishes the filtering, pulp washing and crushing process enters a centrifugal washing and separating system, and the core equipment of the centrifugal washing and separating system is a centrifugal machine. The centrifuge comprises a rotary drum and other components, wherein the rotary drum is mainly used for storing lithium carbonate slurry and performing centrifugal separation on the slurry.

And (3) carrying out centrifugal separation (solid-liquid separation) on the lithium carbonate slurry entering the rotary drum of the centrifuge through a filter bag lined in the rotary drum by utilizing the centrifugal force generated by the high-speed operation of the rotary drum to obtain lithium carbonate solid and th filtrate containing soluble impurities, wherein the lithium carbonate solid is remained in the rotary drum, and the th filtrate containing the soluble impurities is discharged to a th recovery mechanism through a liquid outlet.

(2) Centrifugal washing

When the content of soluble impurities in the lithium carbonate is low, the washing effect of centrifugal washing is good, the efficiency is high, and the content of the impurities can be further reduced by .

Likewise, to increase the solubility of soluble impurities and reduce lithium carbonate peritection, the temperature of the deionized water may also be maintained at 80-90 ℃.

(3) Second centrifugal separation

And after the centrifugal washing is finished, performing second centrifugal separation (solid-liquid separation) on the lithium carbonate slurry in the rotary drum by using the centrifugal force generated by the high-speed operation of the rotary drum again to obtain a lithium carbonate semi-dry solid and a second filtrate. And discharging the second filtrate containing soluble impurities to a second recovery mechanism.

And after the filtration is finished, braking by using a braking electric appliance unit to stop the rotary drum, opening the cover, taking the material (lithium carbonate semi-dry solid) out of the machine to a discharging place by using a bag hanging tool, and finishing discharging, namely finishing complete centrifugal washing separation processes.

(4) Multistage centrifugal washing separation

Optionally, to limit the amount of soluble impurities in the lithium carbonate, the centrifugal washing separation process may further comprise steps of or more times of the above steps (1), (2) and (3) independently and sequentially.

In the centrifugal washing separation system of the 2 nd or higher stage, only the above steps (2) and (3) are required.

And (3) centrifugally washing and separating the lithium carbonate slurry to finally obtain the lithium carbonate semi-dry solid with high cleanliness (namely the lithium carbonate semi-finished product). And finishing the lithium carbonate washing process flow.

The lithium carbonate semi-finished product can enter a subsequent working section for other treatment.

2. Lithium carbonate washing device

th embodiment

Fig. 1 shows a process flow according to embodiments of the present invention, in which a lithium carbonate washing apparatus includes filter pulp washing and pulverizing systems 100 and centrifugal washing and separating systems 200.

(2.1) Filter pulp washing pulverizing System 100

As shown in fig. 1, the filtration-pulp-washing pulverization system 100 includes a filtration mechanism 101, a filtration recovery mechanism 102, a pulp washing mechanism 103, a steam filtration mechanism 104, a pulverization mechanism 105, and a conveyance mechanism 106.

The filter mechanism 101 may comprise primarily a plate and frame filter press. The lithium carbonate slurry generated in the lithium conversion and precipitation working section is subjected to solid-liquid separation in the 1 st stage of slurry washing to obtain a filter cake and a filtrate containing impurities, wherein the filter cake enters the slurry washing mechanism 103 of the stage, and the filtrate containing impurities enters the filtration and recovery mechanism 102 and is recycled after being processed.

The filtering and recovering mechanism 102 may mainly comprise a filtrate storage tank, a bag filter and a transfer pump, and may store the filtrate from the plate and frame filter press, recover lithium carbonate remaining in the filtrate, and transfer the final remaining filtrate to an upstream process for recycling, thereby reducing water resource consumption. The recovery rate of lithium carbonate in the filtrate of the plate-and-frame filter press can reach more than 99 percent. The recovery rate is a ratio of lithium carbonate recovered from the filtrate of the plate and frame filter press to lithium carbonate contained in the filtrate.

The slurry washing mechanism 103 can comprise a washing slurry tank and a stirring member arranged in the washing slurry tank, deionized water is input from the top of the slurry washing mechanism 103 in advance, then a lithium carbonate filter cake from the filtering mechanism 101 is added, the stirring member is used for stirring to obtain uniform lithium carbonate slurry, and the lithium carbonate is primarily washed, meanwhile, steam is introduced from the bottom of the slurry washing mechanism 103, so that the temperature of the materials is kept in relatively constant temperature ranges, such as 80-90 ℃, the solubility of soluble impurities is increased, the impurities are favorably dissolved in the deionized water and then filtered out, and the quality stability of finished products after the impurities are removed is favorably controlled.

The steam filtering mechanism 104 may be formed by a steam filter, which filters impurities in the pipe with the steam after the steam enters the steam filtering mechanism, so as to ensure the cleanliness of the steam, and simultaneously, the steam filter discharges condensed water from the bottom of the steam filter in time, so as to carry out partial impurities in the pipe and maintain the steam temperature, in embodiments of the present invention, the temperature of the steam may be 160 ℃.

The uniformly mixed lithium carbonate slurry from the bottom of the slurry washing mechanism 103 is continuously fed to the crushing mechanism 105 through the th valve 11.

The crushing mechanism 105 may be constituted by 1 high-speed shear pump. The high-speed shear pump can be matched with a 3-stage impeller, the maximum rotating speed can reach 2900r/min, and the maximum flow can be 30m³H, particle diameter D of the slurry after being crushed₅₀May be 20-30 μm. Fully crushing the slurry, and breaking the peritectic crystal of the lithium carbonate and the false package formed by the lithium carbonate and air.

And the crushed lithium carbonate slurry is circulated back to the slurry washing mechanism 103, the crushed and refined lithium carbonate in the slurry can be fully contacted with the deionized water, and soluble impurities are more easily dissolved in the deionized water and are filtered in a lower centrifugal washing separation system. Thereby realizing circulation and deep washing.

After a set period of , the lithium carbonate slurry completes multiple slurry washing and crushing cycles, then the valve 11 is closed, the second valve 12 is opened, and all the lithium carbonate slurry enters the conveying mechanism 106 through the second valve 12 via the output pipeline at the bottom of the slurry washing mechanism 103, the conveying mechanism 106 can be a centrifugal pump, and the lithium carbonate slurry is conveyed to the centrifugal washing and separating system 200 below through the conveying mechanism 106.

(2.2) centrifugal washing separation System 200

As shown in fig. 1, the centrifugal washing and separating system 200 includes a centrifugal washing and separating mechanism 201, an -th recovery mechanism 202, and a second recovery mechanism 203.

The centrifugal washing and separating mechanism 201 may include centrifuges (e.g., 6 centrifuges), which may be a punching bag discharging centrifuge, wherein the surfaces of the components contacting the materials in the centrifuges may be all made of corrosion resistant stainless steel and subjected to a finish polishing treatment, the joints are rounded off, no right angle bending is caused, no residue is left in the batch materials, the working capacity of a single centrifuge may be 320L, the maximum rotation speed may be 1000r/min, the separation factor may be 0-700, the production capacity is 300kg/h, and the total production capacity of six centrifuges is 1.8 t/h.

And injecting the lithium carbonate slurry subjected to slurry washing and crushing into a rotary drum of a centrifuge by a conveying mechanism 106 of a filtering slurry washing and crushing system for th centrifugal separation, wherein the rotary drum rotates at a high speed, solid-liquid separation is realized by a filter bag in the lining of the rotary drum, solids and th filtrate are obtained, the solids are remained in the filter bag, and the th filtrate is discharged from the bottom of the centrifuge to a th recovery mechanism 202.

And then, deionized water enters the high-efficiency washing nozzle through an inlet at the top of the centrifuge, and the solids left in the rotary drum filter bag are centrifugally washed for hours.

And after the centrifugal washing is finished, performing second centrifugal separation to obtain a lithium carbonate semi-finished product 5 (lithium carbonate semi-dry solid) and a second filtrate. The second filtrate is discharged from the bottom of the centrifugal washing and separating mechanism 201 to the second recovery mechanism 203, and then is conveyed to the upstream process, so that the water resource is recovered and utilized.

And after the second centrifugal separation is finished, braking the centrifugal machine, stopping the rotary drum, opening the machine cover, and taking the lithium carbonate semi-finished product 5 out of the machine by using a hanging bag tool. The quick-loading hanging bag unloading mode is adopted for unloading, so that the labor intensity can be greatly reduced, the production period is shortened, and the production capacity is improved.

The th recovery mechanism 202 and the second recovery mechanism 203 may each include a storage tank and a transfer pump.

The process pipelines and tanks in the filtering, pulp washing and crushing system 100 and the centrifugal washing and separating system 200 can be made of titanium TA2, and the parts of the pump and the centrifuge which are in direct contact with the materials can be made of stainless steel 316L.

Second embodiment

Figure 2 shows a process scheme according to another embodiments of the invention using a lithium carbonate washing apparatus including three filter pulp washing comminution systems 100 and two centrifugal washing separation systems 200.

In fig. 2, the 2 nd and 3 rd stage filtering, pulp washing and pulverizing systems are the same as the 1 st stage filtering, pulp washing and pulverizing system, and the adopted process flow is also the same, the filtering mechanism is connected with the pulp processed by the first th stage pulp washing and pulverizing system, and carries out the same processing (filtering, pulp washing and pulverizing) as that in the 1 st stage filtering, pulp washing and pulverizing system, so as to realize the three-stage filtering, pulp washing and pulverizing, and the pulp after the three-stage filtering, pulp washing and pulverizing is conveyed to the following centrifugal washing and separating system 200 by the conveying mechanism in the 3 rd stage system.

In fig. 2, two centrifugal washing and separating systems 200 are used, which are the same, and the process flow adopted is basically the same, except that the centrifugal washing and separating mechanism 201 of the 2 nd-stage centrifugal washing and separating system is connected to the lithium carbonate semi-dry solid output by the 1 st-stage centrifugal washing and separating system, and at this time, the th centrifugal separation is not needed, and only the centrifugal washing and the second centrifugal separation are needed, so that the final lithium carbonate semi-finished product 5 is obtained.