Efficient leaching and purifying method for lithium clinker

Abstract

The invention provides a lithium clinker efficient leaching and purifying method which comprises the steps that S1, lithium clinker is provided, the particle size of the lithium clinker is 6-8 mm, the porosity of the lithium clinker is larger than 40%, and the waste heat temperature of the lithium clinker is 50-80 DEG C; s2, the lithium clinker is put into leaching pools 1 # to 8 # which are sequentially communicated in a dynamic leaching purification system in batches, each leaching pool is subjected to internal circulation strengthening, liquid flow covers the whole pool so as to eliminate a dead zone, cross-pool liquid transfer is adopted between the adjacent leaching pools, leaching liquid is transferred to adjacent pool groups, and the liquid amount dynamic balance is kept so as to improve the utilization rate of the leaching liquid; s3, when the leachate of one leaching pool is concentrated until Li < + > is larger than or equal to 13 g / L, the leachate of the leaching pool is transferred to an impurity removal pool; s4, adding a Ca (OH) 2 solution into the impurity removal tank to adjust the pH value to 6.5-7.0, and carrying out primary fluorine removal; s5, applying an external magnetic field to the impurity removal tank for secondary magnetization sedimentation; and S6, carrying out filter pressing and purification on the product subjected to secondary magnetization sedimentation.

Description

Technical Field

[0001] This application relates to the field of lithium refining technology, and in particular to a method for efficient leaching and purification of lithium clinker. Background Technology

[0002] Lithium extraction is a core link in the new energy industry chain, and the leaching efficiency of lithium clinker directly affects the lithium recovery rate and production cost. In traditional processes, spodumene or lepidolite needs to be calcined at high temperatures (such as in a tunnel kiln or rotary kiln) to form porous clinker, which is then extracted through leaching. However, existing technologies generally suffer from the following problems: 1. Long leaching cycle and low efficiency: Traditional leaching processes (such as static soaking) require 5-7 days, resulting in a Li2O residue of 0.3%-0.5% in the leaching residue and a lithium leaching rate of only 70%-80%. For example, a company using a tunnel kiln to roast clinker (Li2O content 1.2%) found that after 4 days of leaching, the Li2O content in the residue was still 0.35%, and the lithium recovery rate was less than 75%.

[0003] 2. Energy consumption and environmental pressure: High-temperature roasting (such as rotary kiln requiring 930℃) and long-term leaching result in high energy consumption (≥60kWh of electricity per ton of clinker), and the accumulation of impurities such as fluorine and iron in the leachate requires multi-stage purification, increasing wastewater treatment costs by more than 30%.

[0004] 3. Poor adaptability to raw materials: Traditional processes lack precise control over the ratio of raw materials and auxiliary materials and the particle size of granulation, resulting in uneven structure of the roasted clinker and poor permeability of the leachate. For example, in one case, due to the excessively large particle size (>15mm), the leachate could not penetrate the interior of the clinker, and the lithium leaching rate plummeted to 65%.

[0005] 4. Rigid processes: Existing technologies mostly rely on fixed parameters (such as a liquid-to-solid ratio of 3:1 and a leaching temperature of room temperature), lacking dynamic adjustment capabilities and making it difficult to adapt to changes in the grade and physical properties of different lithium ores.

[0006] Due to the aforementioned issues, the contradiction between the surge in lithium resource demand and inefficient processes has become prominent; environmental regulations are becoming increasingly stringent, and traditional high-energy-consuming and high-polluting processes are becoming unsustainable; there is an urgent need to achieve the goal of "short cycle and high leaching rate" through raw material optimization and process innovation.

[0007] In existing technologies, lithium leaching for deterioration includes the following three main methods: 1) Tunnel kiln roasting and static leaching method: The tunnel kiln roasting process mainly includes: a roasting temperature of 900-950℃, a granulation particle size of 10-15mm, and a Li2O content of 1.2%-1.3% in the clinker. The static leaching process mainly includes: static soaking for 4-6 days, a liquid-to-solid ratio of 3:1, and leaching at room temperature. The above processes have the following disadvantages: low leaching rate: after 4 days of leaching, the residual Li2O in the slag is only 0.35%-0.45%, and the lithium recovery rate is only 70%-75%; high energy consumption: the energy consumption of tunnel kiln roasting is 1.2 times that of rotary kiln roasting, and the long leaching cycle leads to increased overall costs; and coarse particle size control: the granulation particle size is too large, resulting in low leachate penetration efficiency (after 4 days of leaching, the Li2O content in the slag is 0.42%, the lithium recovery rate is 73%, and subsequent purification costs account for 35% of the total cost).

[0008] 2) Rotary kiln firing + intermittent circulating leaching method: The main process of rotary kiln roasting: the rotary kiln roasting temperature is 930℃, the granulation particle size is 8-12mm, and the clinker Li2O content is 1.25%; the main process of intermittent circulation leaching: intermittent circulation (Q=100m³ / h pump), leaching cycle is 4 days, leaching at room temperature (slag Li2O content is 0.28%, lithium recovery rate is 78%). Disadvantages: (1) Insufficient circulation efficiency: the low pump flow rate leads to poor flow of leaching liquid at the edge of the pool, and slag Li2O residue is 0.25%-0.3%; (2) Serious accumulation of impurities: the fluoride ion concentration in the circulating liquid reaches 500mg / L, and additional defluorinating agent needs to be added (cost increases by 20%); (3) High dependence on manual labor: liquid level and pH adjustment depend on manual labor, and the process stability is only 80%.

[0009] 3) High-temperature enhanced leaching method: Process parameters: leaching temperature 60-80℃, liquid-solid ratio 2:1, leaching cycle 3 days; energy consumption and effect: steam heating energy consumption is 0.4 tons / ton of clinker, and lithium recovery rate is increased to 80%-85%. Disadvantages: (1) High temperature aggravates the leaching of impurities: iron and aluminum ion concentrations increase by 50%, and subsequent multi-stage chemical precipitation is required, which leads to frequent failure of ion exchange resin. Summary of the Invention

[0010] The purpose of this invention is to solve the above-mentioned problems by providing a highly efficient leaching and purification method for lithium clinker.

[0011] The technical solution of this application is implemented as follows: This invention provides a method for efficient leaching and purification of lithium clinker, comprising the following steps: S1, providing lithium clinker, wherein the particle size of the lithium clinker is 6~8mm, the porosity of the lithium clinker is greater than 40%, and the residual heat temperature of the lithium clinker is 50~80℃. S2, the lithium clinker is fed into the sequentially connected 1#~8# leaching tanks in the dynamic leaching purification system in batches. Each leaching tank adopts internal circulation enhancement, and the liquid flow covers the entire tank to eliminate dead zones. Furthermore, inter-tank liquid transfer is adopted between adjacent leaching tanks to transfer the leaching liquid to the adjacent tank group, maintaining a dynamic balance of liquid volume to improve the utilization rate of leaching liquid. S3, when the leachate from one of the leaching tanks is concentrated to Li + When the concentration is ≥13g / L, the leachate from the leaching tank is transferred to the impurity removal tank. S4, Ca(OH)2 solution is added to the impurity removal tank to adjust the pH to 6.5-7.0 for primary fluoride removal; S5, apply an external magnetic field to the impurity removal tank to perform secondary magnetization sedimentation; S6 is used to filter and purify the product after secondary magnetization sedimentation.

[0012] As a further improvement, the method for preparing the lithium clinker includes the following steps: Lithium mica ore and additives are mixed at a mass ratio of 6:1 to prepare particles with a particle size of 6-8 mm. The additives are a mixture of semi-coke, Na2CO3 and CaSO4. The particles are then added to a rotary kiln, and the calcination temperature of the rotary kiln is controlled at 930℃±10℃ for 2 hours. After the calcined lithium clinker is discharged from the kiln, it is cooled in a waste heat boiler. After the waste heat is recovered, it is directly put into the leaching tank. The waste heat temperature of the lithium clinker after waste heat recovery is maintained at 50~80℃.

[0013] As a further improvement, the internal circulation uses a flow rate Q of 100~200m³. 3 A high-pressure spray pump with a flow rate of / h; the cross-pool liquid transfer uses a flow rate Q of 150~250m³ / h. 3 A high-pressure spray pump with a capacity of / h.

[0014] As a further improvement, the primary defluorination specifically includes: A Ca(OH)2 solution with a mass concentration of 0.5%-1.0% is added to the impurity removal tank to adjust the pH to 6.5-7.0 for primary fluoride removal.

[0015] As a further improvement, the secondary magnetization sedimentation specifically includes: An external magnetic field with an intensity of 0.5-1.2T is applied to the impurity removal tank to accelerate the flocculation and sedimentation of iron and aluminum impurities.

[0016] As a further improvement, the step of pressure filtration specifically includes: using a plate filter press with a filtration accuracy of less than or equal to 10 μm to trap fine particles, so that the suspended solids content of the purified liquid is <50 mg / L.

[0017] As a further improvement, the inter-tank liquid transfer specifically includes: transferring 1 / 3 to 1 / 2 of the total liquid volume in the leaching tank to an adjacent leaching tank daily.

[0018] The advantages or beneficial effects of the above technical solutions include at least the following: (1) Break through the leaching efficiency bottleneck and shorten the cycle to 4 days; To address the issues of long leaching cycles (5-7 days) and low lithium leaching rates (70%-80%) in traditional processes, this paper proposes a new method. By optimizing the ratio of raw materials and auxiliary materials (lithium material / additive mass ratio 6:1) and precisely controlling the granulation particle size (6-8mm), combined with a dynamic liquid flow system (internal circulation spraying + cross-group liquid transfer), the leaching cycle is shortened to 4 days, and the residual Li2O in the residue is reduced to 0.188% (leaching rate ≥85.3%), resulting in an efficiency improvement of 16.66%-20% compared to traditional processes.

[0019] (2) Overcome the problem of impurity interference and simplify the subsequent purification process; To address the high purification costs caused by the leaching of fluorine, iron, and aluminum impurities, a staged impurity removal process was developed: Stage 1: Fluorine removal: Adding Ca(OH)₂ (0.5%-1.0%) combined with pH adjustment (6.5-7.0), achieving a fluorine removal rate >85%; Stage 2: Magnetized sedimentation: Applying an external magnetic field (0.5-1.2T) accelerates the flocculation of iron and aluminum impurities, increasing sedimentation efficiency by 50%; Precision pressure filtration: A plate filter press (filtration accuracy ≤10μm) traps fine particles, resulting in a suspended solids content in the purified liquid <50mg / L, reducing subsequent purification costs by 40%. (Li in the leachate...) + With a concentration ≥13g / L, after concentration and impurity removal, it can be directly used for lithium carbonate preparation, greatly reducing subsequent purification processes and costs. Attached Figure Description

[0020] The accompanying drawings illustrate exemplary embodiments of the present application and, together with the description thereof, serve to explain the principles of the present application. These drawings are included to provide a further understanding of the present application and are incorporated in and constitute a part of this specification.

[0021] Figure 1 A flowchart of a high-efficiency leaching and purification method for lithium clinker provided in an embodiment of the present invention is shown.

[0022] Figure 2 The diagram shows a framework of a dynamic leaching purification system used in a high-efficiency leaching purification method for lithium clinker provided in an embodiment of the present invention. Detailed Implementation

[0023] Embodiments of this application will now be described in more detail with reference to the accompanying drawings. While some embodiments of this application are shown in the drawings, it should be understood that this application can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of this application. It should be understood that the drawings and embodiments of this application are for illustrative purposes only and are not intended to limit the scope of protection of this application.

[0024] It should be noted that, where there is no conflict, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0025] The names of the messages or information exchanged between multiple devices in the embodiments of this application are for illustrative purposes only and are not intended to limit the scope of these messages or information.

[0026] Reference Figure 1 As shown in the figure, this invention provides a method for efficient leaching and purification of lithium clinker, comprising the following steps: S1, providing lithium clinker, wherein the particle size of the lithium clinker is 6~8mm, the porosity of the lithium clinker is greater than 40%, and the residual heat temperature of the lithium clinker is 50~80℃. S2, the lithium clinker is fed into the sequentially connected 1#~8# leaching tanks 10 in the dynamic leaching purification system in batches. Each leaching tank 10 adopts internal circulation enhancement, and the liquid flow covers the entire tank to eliminate dead zones. Furthermore, inter-tank liquid transfer is adopted between adjacent leaching tanks 10 to transfer the leaching liquid to the adjacent tank group, maintaining a dynamic balance of liquid volume to improve the utilization rate of leaching liquid. S3, when the leachate from one of the leaching tanks 10 is concentrated to Li + When the concentration is ≥13g / L, the leachate from the leaching tank 10 is transferred to the impurity removal tank 16. S4, Ca(OH)2 solution is added to the impurity removal tank 16 to adjust the pH to 6.5-7.0 for primary fluoride removal; S5, apply an external magnetic field to the impurity removal tank 16 to perform secondary magnetization sedimentation; S6 is used to filter and purify the product after secondary magnetization sedimentation.

[0027] In step S1, the lithium clinker is formed by mixing lepidolite with additives, followed by granulation and calcination. Specifically, the preparation method of the lithium clinker includes the following steps: Lithium mica ore was mixed with additives (semi-coke, Na2CO3, CaSO4) at a mass ratio of 6:1 to prepare particles with a particle size of 6~8mm. The particles are then added to a rotary kiln, and the calcination temperature of the rotary kiln is controlled at 930℃±10℃ for about 2 hours. The Li2O content in the calcined lithium clinker is stable at 1.28%-1.30%. In one embodiment, the Li2O content in the calcined lithium clinker is stable at 1.29%.

[0028] After the calcined lithium clinker is discharged from the kiln, it is cooled in a waste heat boiler. After the waste heat is recovered, it is directly put into the leaching tank 10. The waste heat temperature of the lithium clinker can be maintained at 50~80℃ after the waste heat is recovered.

[0029] Preferably, steps S2-S6 are implemented using a dynamic leaching purification system. Please refer to [link to relevant documentation]. Figure 2 As shown, the dynamic leaching purification system includes: The 1#~8# leaching tanks 10 are connected in sequence, and the 8# leaching tank is connected to the 1# leaching tank to form a loop. The two leaching tanks 10 are connected to each other through the first cross-group circulation pump 12, and each leaching tank 10 is equipped with an internal circulation pump 11. The water in the storage tank 14 is connected to each leaching tank 10 through the first cross-group conduit 13, and a control valve 15 is provided between each leaching tank 10 and the first cross-group conduit 13. The impurity removal tank 16 is connected to each leaching tank 10 via a second cross-group conduit 18, and a second cross-group circulation pump 19 is provided between each leaching tank 10 and the second cross-group conduit 18; the impurity removal tank 16 also includes an impurity removal agent inlet pipe 20. The filter press assembly 21 is connected to the discharge port of the impurity removal tank 16; The purification component 22 is connected to the discharge port of the filter press component 21.

[0030] Preferably, each leaching tank 10 is 27 meters long, 9 meters wide, and 1 meter high. In one embodiment, leaching tanks 1# to 4# are defined as the first group, and leaching tanks 5# to 8# are defined as the second group. The amount of roasting on the first day is placed into each leaching tank 10 in the first group (about 3200 tons), and the amount of roasting on the second day is placed into each leaching tank 10 in the second group.

[0031] To facilitate subsequent automated control, a liquid level sensor (not shown in the figure) can be further installed in each leaching tank 10. This sensor detects the liquid level in each leaching tank 10 and then replenishes the tank with water from the storage tank 14 to reach the preset level. The water in the storage tank 14 is distilled water. Various ion sensors (not shown in the figure) can also be installed in each leaching tank 10 to acquire real-time ion parameters such as F ion concentration (line fluoride ion selective electrode (ISE)), Li ion concentration (line lithium ion selective electrode (ISE)), and pH value (online pH electrode). Specifically, to achieve automated control, this invention further integrates a PLC central control system, which connects to various sensors, valves, and spray pumps. This PLC central control system monitors and automatically adjusts parameters such as liquid level, pH (4-6), and various ion concentrations in real time, reducing manual intervention by 70% and improving process stability to 95%, providing technical support for large-scale continuous production.

[0032] The internal circulation pump 11 has a flow rate Q of 100~200 m³ / h. 3 A high-pressure spray pump with a spray density of 10~20 L / (m³) is used. 2 The internal circulation spray system (·s) covers the entire pool, eliminating "dead zones." In one embodiment, the internal circulation pump 11 uses a flow rate Q of 150 m³ / s. 3 A high-pressure spray pump with a spray density of 15 L / (m³) is used. 2 ·s).

[0033] The second cross-group circulating pump 19 uses a flow rate Q of 150~250m³ / h. 3 A high-pressure spray pump with a flow rate of / h is used for cross-tank spraying, transferring the leachate to adjacent leach tanks 10 to maintain dynamic balance of liquid volume and maximize the utilization rate of the leachate. In one embodiment, the second cross-group circulation pump 19 uses a flow rate Q of 200m³ / h. 3 A high-pressure spray pump with a flow rate of / h is used. Preferably, 1 / 3 to 1 / 2 of the total liquid volume in the leaching tank 10 is transferred to an adjacent leaching tank 10 daily to maintain a dynamic balance of liquid volume and maximize the utilization rate of the leachate. In one embodiment, 1 / 2 of the total liquid volume in the leaching tank 10 is transferred to an adjacent leaching tank 10 daily.

[0034] It is understandable that during static or small-amplitude internal circulation, the liquid film Li on the particle surface... + The concentration quickly approaches saturation, the concentration boundary layer thickens, and the leaching rate decreases. Removing 1 / 3 to 1 / 2 of the liquid can instantly lower the Li content in the liquid phase. +At concentrations of 30-50%, a significant concentration gradient reforms between the solid and liquid phases, the boundary layer is torn and renewed, and a "second peak" appears in the leaching rate. Additionally, the large-scale transfer of 1 / 3 to 1 / 2 of the leaching solution dilutes the high-fluoride solution across multiple tanks, increasing the leaching rate per tank. - The peak value decreased by 25-35%, Ca(OH)2 consumption decreased by about 15%, and the scaling cycle of pipelines was extended by 1.5 to 2.5 times.

[0035] As a further improvement, in order to save energy, the leachate can be transferred by fully utilizing the combination of the second cross-group circulation pump 19 and gravity flow.

[0036] Specifically, while controlling the second cross-group circulation pump 19 to transfer the leachate from one leaching tank 10 to the next, valves between the other leaching tanks 10 are simultaneously opened, allowing the leachate in the other leaching tanks 10 to flow by gravity, thus significantly saving energy. Only one pump is used as the "starting point," while the remaining connecting valves are opened, utilizing the liquid level difference (tank depth 1 m) to allow the liquid to flow synchronously between all adjacent tanks. Actual measurements show that the 8-tank series system saves over 65% of daily electricity. Furthermore, gravity flow allows high-Li... + Liquid automatically flows to low Li + The system is filled in zones, and the flow stops when the liquid level difference is maintained at 2-3 cm. The system automatically finds its balance and does not require manual adjustment of the liquid level. For example, when controlling the second cross-group circulation pump 19 to transfer the leachate from leaching tank 10 to leaching tank 2, the valves between leaching tanks 3-8 and between leaching tank 10 are opened at the same time, allowing the leachate between the other leaching tanks 10 to flow by gravity.

[0037] Because the disturbance force and flow rate of gravity flow between leaching tanks 10 are relatively small, in order to increase the disturbance force and flow rate between leaching tanks 10, preferably, at least two second cross-group circulation pumps 19 are controlled to transfer the leachate from one leaching tank 10 to the next leaching tank 10 while simultaneously opening the valves between other leaching tanks 10, allowing the leachate between other leaching tanks 10 to flow by gravity. For example, while controlling the second cross-group circulation pump 19 to transfer the leachate from leaching tank 1# to leaching tank 2#, and controlling the second cross-group circulation pump 19 to transfer the leachate from leaching tank 5# to leaching tank 6#, the valves between leaching tanks 3#~4#, 7#~8#, and 8# and 1# are opened, allowing the leachate between other leaching tanks 10 to flow by gravity.

[0038] In other embodiments, to extend the service life of the second cross-group circulation pump 19 and enhance the flow efficiency between the various leaching tanks 10, the second cross-group circulation pump 19 can be controlled to operate sequentially. Specifically, the second cross-group circulation pump 19 between leaching tank 1# and leaching tank 2# is turned on at time T1, the second cross-group circulation pump 19 between leaching tank 2# and leaching tank 3# is turned on at time T2, the second cross-group circulation pump 19 between leaching tank 3# and leaching tank 4# is turned on at time T3, and so on. The system changes from a one-time group breathing to a sequential wave-like progression, with only one channel having pump pressure at each time period, while the other valves remain open for gravity flow, but without reverse impact; the liquid phase always follows a unidirectional flow from 1#->2#->3#->…->8#, eliminating high Li caused by backflow short circuits. + The liquid level in the next working pool is lowered by 3-5 cm, while the upstream pool maintains a high level. The process then rotates to the downstream pool in the next period, maintaining a level difference of 2-4 cm. The gravity-driven flow does not diminish, and no additional pumps are needed throughout the day. This "pool-by-pool rotation" transforms continuous large-scale circulation into sequential small pulses, using time-staggered timing to achieve spatial pressure differences. This further reduces power consumption, smooths concentration distribution, and eliminates short-circuit occurrences, making it a scheduling method that maintains high mass transfer with ultra-low power consumption.

[0039] Alternatively, at time T1, the second cross-group circulation pump 19 between leaching tank 10 and leaching tank 2, and between leaching tank 5 and leaching tank 6, can be turned on; then at time T2, the second cross-group circulation pump 19 between leaching tank 2 and leaching tank 3, and between leaching tank 7 and leaching tank 8, can be turned on, and so on.

[0040] It is understandable that the above treatment can greatly shorten the leaching cycle and increase the leaching rate, reducing the leaching cycle to 4 days and the lithium leaching rate to ≥85.3% (Li2O residue in the slag is reduced to 0.188%), while the lithium leaching rate of traditional leaching processes is only about 70%-80%.

[0041] In other embodiments, the impurity removal tank 16 further includes a second internal circulation pump 17 for internal circulation spraying. Both the primary fluoride removal and the secondary magnetization sedimentation are carried out in the impurity removal tank 16.

[0042] Specifically, the primary defluorination includes: A Ca(OH)₂ solution with a mass concentration of 0.5%-1.0% is added to the impurity removal tank 16 to adjust the pH to 6.5-7.0 for primary fluoride removal. During this process, calcium ions react with fluoride ions to form calcium fluoride precipitate, thereby removing fluoride and achieving a fluoride ion removal rate greater than 85%.

[0043] Specifically, the secondary magnetization sedimentation includes: By applying an external magnetic field with an intensity of 0.5-1.2T to the impurity removal tank 16, the flocculation and sedimentation of iron and aluminum impurities can be accelerated, thereby shortening the sedimentation time by 50%.

[0044] The step of pressing and filtering the product after secondary magnetization sedimentation is implemented in the pressure filter assembly 21. Specifically, a plate filter press (filtration accuracy ≤10μm) is used to retain fine particles, and the suspended solids content of the purified liquid is <50mg / L for pressure filtration.

[0045] Example 1: Lithium mica ore was mixed with additives (semi-coke, Na2CO3, CaSO4) at a mass ratio of 6:1 (0.5:0.3:0.2) to prepare particles with a diameter of 6-8 mm. These particles were then added to a rotary kiln, and the roasting temperature was controlled at 930℃±10℃ for approximately 2 hours. Testing showed that the Li2O content in the roasted lithium clinker remained stable at 1.29%. After exiting the kiln, the roasted lithium clinker was cooled in a waste heat boiler. After waste heat recovery, it was directly fed into leaching tank 10, where the waste heat temperature was maintained at approximately 60℃. The lithium clinker was then leached in batches into leaching tank 10 of a dynamic leaching purification system for approximately 4 days. When the leachate from one of the leaching tanks was concentrated to a concentration of Li... + When the concentration is ≥13 g / L, the leachate from leaching tank 10 is transferred to impurity removal tank 16; then, Ca(OH)₂ solution is added to impurity removal tank 16 to adjust the pH to 6.5 for primary fluoride removal; then, an external magnetic field is applied to impurity removal tank 16 for secondary magnetization sedimentation; finally, the product after secondary magnetization sedimentation is filtered to obtain filtrate and filter residue. During the leaching process, lithium clinker is sampled and analyzed daily, as shown in Table 1.

[0046] Table 1 shows the Li₂O content and leaching rate data in lithium clinker.

[0047] As can be seen from Table 1, the leaching rate of the present invention in the final 4-day leaching process can reach 85.3%, which is 12.6% higher than that of the tunnel kiln process (slag Li2O, 0.35%); and 7.14% higher than that of the rotary kiln process (slag Li2O, 0.28%); and 2.46% higher than that of the high-temperature leaching method (slag Li2O, 0.22%).

[0048] Those skilled in the art should understand that the above embodiments are merely for illustrative purposes and are not intended to limit the scope of this application. Those skilled in the art can make other changes or modifications based on the above disclosure, and these changes or modifications still fall within the scope of this application.

Claims

1. A method for efficient leaching and purification of lithium clinker, characterized in that: Includes the following steps: S1, providing lithium clinker, wherein the particle size of the lithium clinker is 6~8mm, the porosity of the lithium clinker is greater than 40%, and the residual heat temperature of the lithium clinker is 50~80℃. S2, the lithium clinker is fed into the sequentially connected 1#~8# leaching tanks in the dynamic leaching purification system in batches. Each leaching tank adopts internal circulation enhancement, and the liquid flow covers the entire tank to eliminate dead zones. Furthermore, inter-tank liquid transfer is adopted between adjacent leaching tanks to transfer the leaching liquid to the adjacent tank group, maintaining a dynamic balance of liquid volume to improve the utilization rate of leaching liquid. S3, when the leachate from one of the leaching tanks is concentrated to Li + When the concentration is ≥13g / L, the leachate from the leaching tank is transferred to the impurity removal tank. S4, Ca(OH)2 solution is added to the impurity removal tank to adjust the pH to 6.5-7.0 for primary fluoride removal; S5, apply an external magnetic field to the impurity removal tank to perform secondary magnetization sedimentation; S6 is used to filter and purify the product after secondary magnetization sedimentation.

2. The method for efficient leaching and purification of lithium clinker according to claim 1, characterized in that: The method for preparing the lithium clinker includes the following steps: Lithium mica ore and additives are mixed at a mass ratio of 6:1 to prepare particles with a particle size of 6-8 mm. The additives are a mixture of semi-coke, Na2CO3 and CaSO4. The particles are then added to a rotary kiln, and the calcination temperature of the rotary kiln is controlled at 930℃±10℃ for 2 hours. After the calcined lithium clinker is discharged from the kiln, it is cooled in a waste heat boiler. After the waste heat is recovered, it is directly put into the leaching tank. The waste heat temperature of the lithium clinker after waste heat recovery is maintained at 50~80℃.

3. The method for efficient leaching and purification of lithium clinker according to claim 1, characterized in that: The internal circulation uses a flow rate Q of 100~200m³. 3 A high-pressure spray pump with a flow rate of / h; the cross-pool liquid transfer uses a flow rate Q of 150~250m³ / h. 3 A high-pressure spray pump with a capacity of / h.

4. The efficient leaching and purification method for lithium clinker according to claim 1, characterized in that: The primary defluorination specifically includes: A Ca(OH)2 solution with a mass concentration of 0.5%-1.0% is added to the impurity removal tank to adjust the pH to 6.5-7.0 for primary fluoride removal.

5. The efficient leaching and purification method for lithium clinker according to claim 1, characterized in that: The secondary magnetization sedimentation specifically includes: An external magnetic field with an intensity of 0.5-1.2T is applied to the impurity removal tank to accelerate the flocculation and sedimentation of iron and aluminum impurities.

6. The method for efficient leaching and purification of lithium clinker according to claim 1, characterized in that: The specific steps of pressure filtration include: using a plate filter press with a filtration accuracy of less than or equal to 10 μm to trap fine particles, so that the suspended solids content of the purified liquid is <50 mg / L.

7. The efficient leaching and purification method for lithium clinker according to claim 1, characterized in that: The cross-tank liquid transfer specifically includes: transferring 1 / 3 to 1 / 2 of the total liquid volume in the leaching tank to the adjacent leaching tank each day.

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