Efficient conversion method for lithium salt production

Abstract

The invention discloses an efficient conversion method for lithium salt production. The method comprises the following steps: step 1, mixing a lithium sulfate finished solution, a primary evaporative crystallization mother solution from lithium hydroxide and a sodium precipitation mother solution to obtain a mixed mother solution; 2, accurately metering and pumping the mixed mother liquor and liquid caustic soda through a metering pump according to the ratio of OH <-> to Li2O being 1.3-1.5, and conveying the mixed mother liquor and the liquid caustic soda into a pipeline premixer for premixing; 3, then, the converted premixed liquid enters a strong mixing conversion device (1) to be converted, the feeding pressure is set to be 0.1-0.3 Mpa, the rotating speed of a rotary drum is set to be 1200-2000 rpm / min, full contact is conducted, a mixed system is formed through fusion, and 4, finally, the converted liquid is sent to a sedimentation centrifuge to be subjected to solid-liquid separation, and the converted liquid with the low impurity content is obtained. The production line has the advantages that the production efficiency is improved, the occupied area is reduced, the consumption of auxiliary materials is reduced, the production cost is reduced, and efficient and intelligent production is realized.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of lithium salt production process, and particularly relates to a high-efficiency conversion method for lithium salt production. BACKGROUND

[0002] Lithium spodumene ore is used as raw material to produce battery-grade lithium hydroxide, and a lithium sulfate solution-caustic soda conversion method is mainly used as a mainstream process. In the method, lithium sulfate solution, which is an intermediate material of lithium hydroxide produced by a sulfuric acid method, is used as raw material to add caustic soda NaOH, to form a mixed component system of Li2SO4+Na2SO4+NaOH+LiOH, and then a lithium hydroxide solution is obtained by moving the system to the direction of precipitating Na2SO4·10H2O and generating LiOH through freezing cooling. At present, the production line of this conversion mode is generally mixed mother liquor, that is, lithium sulfate solution mixed with mother liquor after evaporation of lithium hydroxide, and liquid alkali solution are pumped into a conversion tank, mixed in the conversion tank, and then impurities are removed through plate and frame filter pressing and precision filter.

[0003] However, this conversion mode has the following problems: (1) The conversion efficiency of the conversion tank is low, and it is necessary to continuously send samples to detect the OH-:Li2O ratio of the conversion solution to determine whether the conversion is complete, which takes a long time of about 2-3 hours, and the production efficiency is low; (2) The conversion requires a tank for mixing mother liquor, a tank for conversion, a tank, a plate and frame filter, and a precision filter, and the total area occupied by the equipment is large; (3) After conversion, a conversion filter press and a precision filter are required, and the filter cloth of the filter press needs to be cleaned and replaced regularly, which takes a long time, and the replacement of the filter cloth incurs additional costs, so the production cost is high; (4) The precision filter is used for filtering, and after filtering, dilute sulfuric acid is used for regeneration, which increases the consumption cost of auxiliary materials; (5) The plate and frame filter is operated intermittently, and after completing a filtering period, the filter must be stopped for slag removal and filter cloth / filter core washing operation, which seriously hinders the continuity and automation level of production and reduces the overall production efficiency. SUMMARY

[0004] The purpose of the present application is to solve the problems of low conversion efficiency, large area occupied, discontinuous production and high cost in existing lithium salt production, and to provide a high-efficiency conversion method for lithium salt production, which improves production efficiency, reduces area occupied, reduces consumption of auxiliary materials and auxiliary materials, reduces production cost, and is more efficient and intelligent.

[0005] In order to achieve the above-mentioned purpose, the following technical solutions are adopted in the present application: A high-efficiency conversion method for lithium salt production, the specific steps are as follows: (1) mixing lithium sulfate complete liquid, primary evaporation crystallization mother liquor from lithium hydroxide, and sodium precipitation mother liquor to obtain a mixed mother liquor; (2) the above mixed mother liquor and liquid alkali are precisely metered by a metering pump according to OH-:Li2O=1.3~1.5, pumped into a pipeline premixer, and premixed; (3) then, the premixed solution is converted into a strong mixing conversion device, the feeding pressure is 0.1~0.3Mpa, the rotating speed of the rotating drum is 1200~2000rpm / min, and the mixed system is fully contacted and fused; (4) finally, the converted solution is sent to a sedimentation centrifuge for solid-liquid separation, and a converted solution with low impurity content is obtained.

[0006] Further, in the step (3), the chemical reaction of the mixed system is as follows: .

[0007] Further, in the step (2), the mixed mother liquor and the liquid alkali are metered by a metering pump according to OH-:Li2O=1.3~1.5.

[0008] Further, the strong mixing conversion device is connected between the pipeline premixer and the sedimentation centrifuge, and includes a rotating drum, the rotating drum is provided with a feeding port and a discharging port, a spiral blade is arranged in the cavity of the rotating drum, and the spiral blade is provided with a gear-shaped edge.

[0009] Further, the spiral blade is spirally arranged along the axis of the rotating drum.

[0010] Further, a rotating shaft is arranged in the rotating drum, the end of the rotating shaft is connected with the driving end of a motor driving device, and the rotating drum is driven to rotate at a set speed by the motor driving device.

[0011] Further, the spiral blade is equally divided into three parts along the length direction of the rotating drum, and the spiral blade located at the middle part is provided with a gear-shaped edge.

[0012] Compared with the prior art, the technical scheme of the present application has the following advantages: (1) the present application adopts mother liquor to detect lithium oxide content in advance, the mixed mother liquor and the liquid alkali are metered by a metering pump and pumped into a pipeline premixer for premixing, and then the premixed solution is converted into a new conversion device, the new conversion device can strengthen the mixing intensity, promote the mixing uniformity, and improve the conversion efficiency; (2) the present application replaces plate and frame filter pressing and precision filtration with a sedimentation centrifuge for solid-liquid separation, and the sedimentation centrifuge can generate a strong centrifugal force by high-speed rotation, so that the sedimentation separation can be completed in a very short time, and the production efficiency can be improved by 30%; (3) the conversion equipment of the present application has a small footprint, reduces the consumption of dilute acid auxiliary materials and filter cloth auxiliary materials, and greatly reduces the production cost; (4) Compared with plate and frame filtration and precision filtration, the application can reduce production time, realize efficient and intelligent production. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 A flow chart of the efficient conversion method for lithium salt production of the application; Figure 2 A structural schematic diagram of the strong mixing conversion device of the application. DETAILED DESCRIPTION EMBODIMENT

[0014] To make the application clearer, a kind of efficient conversion method for lithium salt production of the application will be further described below in conjunction with the drawings. The specific embodiments described herein are only used to explain the application and do not limit the application.

[0015] Reference Figure 2 The strong mixing conversion device 1 used in the embodiment is characterized by comprising a rotating drum 11, the rotating drum 11 is provided with a feeding port 12 and a discharging port 13, a spiral blade 14 is arranged in the cavity of the rotating drum 11, the spiral blade 14 in the middle section is provided with a gear-shaped edge 14a, the spiral blade 14 is spirally arranged along the axis of the rotating drum 11, a rotating shaft 15 is arranged in the rotating drum 11, the end of the rotating shaft 15 is connected with the driving end of a motor driving device 16, and the rotating drum 11 is driven to rotate at a set speed by the motor driving device 16.

[0016] Participation Figure 1 An efficient conversion method for lithium salt production is characterized by: The mixed mother liquor of lithium sulfate complete liquid, primary evaporation and crystallization mother liquor from lithium hydroxide and sodium precipitation mother liquor, and liquid alkali are precisely metered by a metering pump according to OH-:Li2O=1.3~1.5, and are pre-mixed by a pipeline pre-mixer; The pre-mixed liquid is converted in the above-mentioned strong mixing conversion device 1, the feeding pressure in the strong mixing conversion device 1 is set to 0.1~0.2Mpa, the rotating speed of the rotating drum is 1200~2000rpm / min, and the conversion device is fully contacted and fused into a mixed system; Finally, the conversion liquid is subjected to solid-liquid separation by a sedimentation centrifuge, and the conversion liquid with low impurity content can be obtained.

[0017] The strong mixing conversion device and the sedimentation centrifuge are used in the application, the sedimentation separation can be completed in a very short time, the production efficiency can be improved by 30%, the land occupation area is small, the consumption of dilute acid auxiliary materials and filter cloth auxiliary materials is reduced, the production cost can be reduced, and compared with plate and frame filtration and precision filtration, the production time can be reduced, the production can be efficient and intelligent.

[0018] In addition to the embodiments described above, the present application can have other implementation manners. Any technical solutions formed by equivalent replacement or equivalent transformation fall within the protection scope of the present application.

Claims

1. A highly efficient conversion method for lithium salt production, characterized in that: Step 1: Mix the lithium sulfate solution, the mother liquor from the first evaporation and crystallization of lithium hydroxide, and the sodium precipitation mother liquor to obtain a mixed mother liquor; Step 2: The above mixed mother liquor and liquid alkali are precisely metered and pumped into the pipeline premixer at an OH-:Li2O ratio of 1.3~1.5 using a metering pump, and then premixed. Step 3: Next, the premixed liquid is fed into the strong mixing conversion device (1) for conversion. The feed pressure is set to 0.1~0.3Mpa and the drum speed is 1200~2000rpm / min to ensure full contact and fusion into a mixed system. Step 4: Finally, the conversion liquid is sent to a sedimentation centrifuge for solid-liquid separation, which yields a conversion liquid with low impurity content.

2. The efficient conversion method for lithium salt production according to claim 1, characterized in that: In step three, the chemical reaction of the mixed system is as follows: 。 3. The efficient conversion method for lithium salt production according to claim 1 or 2, characterized in that: In step two, the mixed mother liquor and liquid alkali are pumped in using a metering pump at a ratio of OH-:Li2O = 1.3~1.

5.

4. The efficient conversion method for lithium salt production according to claim 1 or 2, characterized in that: The strong mixing conversion device (1) is connected between the pipeline premixer and the sedimentation centrifuge. It includes a drum (11), with an inlet (12) and an outlet (13) on the drum (11). The drum (11) has a spiral blade (14) inside its cavity, and the spiral blade (14) has a gear-shaped edge (14a).

5. The efficient conversion method for lithium salt production according to claim 4, characterized in that: The spiral blade (14) is arranged to rotate along the axis of the drum (11).

6. The efficient conversion method for lithium salt production according to claim 4, characterized in that: The drum (11) is provided with a rotating shaft (15), the end of which is connected to the driving end of the motor drive device (16). The rotating drum (11) is driven to rotate at a set speed by the motor drive device (16).

7. The efficient conversion method for lithium salt production according to claim 4, characterized in that: The spiral blade (14) is divided into three equal parts along the length of the drum (11), and the spiral blade in the middle section is provided with a gear-shaped edge (14a).

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