Method for improving ternary precursor BET (Brunauer-Emmett-Teller) by unloading of filter press

Abstract

The invention provides a method for improving ternary precursor BET through filter press discharging, and belongs to the technical field of ternary lithium battery precursor materials.The method comprises the steps that the feeding time difference value between experimental production lines of a plate-and-frame filter press is controlled for 60 + / -10 minutes by regulating and controlling the pressure of a pneumatic diaphragm pump and the feeding pressure of a plate frame; the feeding material level of the plate frame of the plate-and-frame filter press is controlled to be 80% + / -10%, and it is guaranteed that the slurry tank can be completely pumped every time; the principle that the materials are firstly treated when entering the slurry tank is followed during material treatment; the time for the plate-and-frame filter press to process a plate-and-frame material is controlled to be 160-165 minutes; after materials in a plate frame of the plate-and-frame filter press are aged, washed, squeezed and purged, the wet material bin and the plate-and-frame filter press are checked before the materials enter the wet material bin; and the time for the plate-and-frame filter press to unload one plate-and-frame material is controlled to be 15-20 minutes. According to the method for improving the ternary precursor BET through unloading of the filter press, provided by the invention, the prepared ternary precursor BET is stable.

Description

Technical Field

[0001] The present invention relates to the technical field of ternary lithium battery precursor materials, and in particular to a method for improving the BET of a ternary precursor by unloading from a filter press. Background Art

[0002] In the field of materials science, ternary materials are materials composed of three different elements. Ternary precursors are typically complexes formed through specific processes using hydroxides of three metal elements: nickel, cobalt, and manganese (NCM) or nickel, cobalt, and aluminum (NCA). These complexes are key intermediates in the preparation of positive electrode materials for lithium-ion batteries. BET is a widely used method in physical chemistry to characterize the adsorption properties of materials.

[0003] In the production process of ternary precursors, BET has always been an indicator of key concern. There are many factors that affect BET, among which the uniformity of the feed to the disc dryer has an important influence on the BET of the ternary precursor. The traditional feeding method in the production of ternary precursors is to unload the entire plate frame material into the hopper after the plate frame has processed the material, and control its feeding speed through the feeder and arch breaker. However, this situation is subject to many restrictions, such as excessive material accumulation leading to uneven feeding speed, and bridging at the bottom of the hopper cannot be discovered in time, which will affect the feeding continuity of the subsequent disc dryer, and may cause uneven material thickness on each disc of the disc dryer, abnormal color change of the disc dryer material, and other problems. Whether the material thickness is too high, resulting in incomplete drying of the material, or the material thickness is too thin, which easily causes overdrying, it will cause the BET of the ternary precursor to fluctuate, thereby affecting the consistency of the BET of the ternary precursor.

[0004] Therefore, there is a need for a method for improving the BET of a ternary precursor by filter press unloading so as to stabilize the BET of the produced ternary precursor. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for improving the BET of a ternary precursor by unloading from a filter press, which can stabilize the BET of the produced ternary precursor.

[0006] To solve the above technical problems, the present invention provides a method for improving the BET of a ternary precursor by unloading from a filter press, comprising:

[0007] The ternary precursor material is aged, washed, pressed and purged in the plate and frame filter press and then enters the wet material bin, then enters the disc dryer for drying, then enters the mixer for mixing, and finally is sieved by the screening machine and packaged to obtain the ternary precursor;

[0008] By regulating the pressure of the pneumatic diaphragm pump and the plate and frame feed pressure, the feed time difference of the 3rd, 4th and 11th 55C model experimental production lines of the plate and frame filter press was controlled to be 60±10 minutes;

[0009] The feed level of the plate and frame filter press is controlled at 80% ± 10% to ensure that the slurry tank of the production line can be pumped empty every time;

[0010] When handling materials, follow the principle of handling the materials in the most advanced slurry tank first;

[0011] The time for the plate and frame filter press to process one plate and frame material is controlled at 160-165 minutes;

[0012] After the materials in the plate and frame filter press are aged, washed, pressed and purged, the wet material bin and the plate and frame filter press are inspected before entering the wet material bin;

[0013] The time it takes for the plate and frame filter press to unload a plate and frame of material is controlled within 15-20 minutes.

[0014] Furthermore, the pressure of the pneumatic diaphragm pump is controlled to be 0.5-0.6 MPa, and the plate and frame feed pressure is controlled to be 0.12-0.15 MPa.

[0015] Furthermore, the inspection of the wet material bin and the plate and frame filter press includes first checking the material level of the wet material bin to ensure that there is no material in the wet material bin, and then checking that there is no liquid accumulation, alkali stains, or oil stains on the plate and frame filter press belt, and that the pressing pressure and feed pressure of the plate and frame filter press are returned to zero.

[0016] Furthermore, the drying temperature of the disc dryer is controlled to be 100-150°C.

[0017] Furthermore, the operating frequency of the mixer is 15-25 Hz, and the mixing time of the ternary precursor material in the mixer is 25-35 minutes.

[0018] The present invention provides a method for improving the BET of a ternary precursor by unloading a filter press. By controlling the duration and speed of unloading the plate and frame filter press and feeding the wet material bin, the material level in the wet material bin is better controlled, and the accumulation of material discharged from the plate and frame filter press in the wet material bin is avoided, thereby avoiding the formation of an arch bridge of material at the bottom of the wet material bin and causing the feeder to run idle.

[0019] In addition, the present invention provides a method for improving the BET of a ternary precursor by unloading a filter press, which controls the material processing time and unloading time of the plate and frame filter press within an appropriate time, so as to facilitate timely cleaning of materials adhering to the bottom of the wet material bin, the broken arch, and the feeder, so that the feeding speed of the wet material bin is consistent each time and is continuously maintained at about 500 kg per hour, ensuring that the solid material bin can smoothly feed the disc dryer, and can stabilize the feeding speed of the disc dryer, thereby stabilizing the BET of the ternary precursor. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1A method and measure diagram for improving the BET of a ternary precursor by filter press unloading provided by an embodiment of the present invention;

[0021] Figure 2 A comparison chart of BET changes of ternary precursors obtained by a method for improving BET of ternary precursors by filter press unloading provided in an embodiment of the present invention and a comparative example. DETAILED DESCRIPTION

[0022] See also Figure 1 The embodiment of the present invention provides a method for improving the BET of a ternary precursor by unloading a filter press, which is applicable to the production of ternary precursors for lithium batteries and specifically includes the following measures and control mechanisms:

[0023] In the production process of ternary precursors, a plate and frame filter press is used to process the ternary precursor materials and a wet material bin is used for unloading.

[0024] Among them, the production process of the ternary precursor includes that the ternary precursor material enters the wet material bin after aging, washing, pressing and purging in the plate frame of the plate and frame filter press, and then enters the disc dryer for drying, and then enters the mixer for mixing, and then uses a screening machine with a screen that matches the particle size of the material to screen the mixture, and finally packages it to produce the ternary precursor.

[0025] Among them, when the ternary precursor material enters the disc dryer for drying, the drying temperature of the disc dryer is controlled at 100-150°C.

[0026] Among them, when the ternary precursor material enters the mixer for mixing, the operating frequency of the mixer is controlled at 15-25 Hz, and the mixing time of the ternary precursor material in the mixer is controlled at 25-35 minutes.

[0027] In addition, by adjusting the pressure of the pneumatic diaphragm pump at 0.5-0.6 MPa and the plate and frame feed pressure at 0.12-0.15 MPa, the feed time difference range of the 3rd, 4th and 11th 55C model experimental production lines of the plate and frame filter press was reduced to 60±10 minutes.

[0028] Moreover, the feed material level of the plate and frame filter press is controlled at 80%±10% to ensure that the slurry tank of the production line can be pumped empty each time.

[0029] At the same time, when the plate and frame filter press processes materials, the principle of processing the materials in the slurry tank first is followed. This can ensure that the materials will not stay in the slurry tank for a long time, thereby preventing the materials from being placed in the slurry tank for a long time and causing oxidation problems.

[0030] When the plate and frame filter press processes material within the plates and frames, the processing time per plate and frame is controlled to 160-165 minutes. Furthermore, when the plate and frame filter press is unloading, the time it takes to unload each plate and frame is controlled to 15-20 minutes. This not only ensures a balanced feed to the wet material bin but also stabilizes the feed rate of the disc dryer. Furthermore, it ensures that the plate and frame filter press processes one plate and frame into the wet material bin every three hours. This ensures that the wet material bin is completely empty within three hours, allowing ample time to clean the bottom of the wet material bin, the broken arch, and any material stuck to the feeder. This ensures a smooth connection between the plate and frame filter press discharge and the wet material bin inflow and outflow, ensuring continuous and uniform feeding of the wet material bin, avoiding frequent equipment starts and stops, and improving production efficiency.

[0031] In addition, after the materials in the plate and frame filter press have been aged, washed, pressed and purged, the wet material bin and the plate and frame filter press are inspected before entering the wet material bin. First, check the material level in the wet material bin to ensure that there is no material in the wet material bin and the bin is empty. Ensure that the material does not accumulate in the bin, so as to ensure that the normal feeding speed of the feeder is not affected. Then check the belt of the plate and frame filter press to ensure that there is no liquid accumulation, alkali stains, or oil stains on the belt. Check whether the pressing pressure and feed pressure of the plate and frame filter press have returned to zero.

[0032] The present invention provides a method for improving the BET of a ternary precursor by unloading a filter press. By controlling the duration and speed of plate and frame unloading and the feeding of a solid material bin, the material level of the wet material bin is better controlled, and it is avoided that more than one plate and frame of material accumulates in the wet material bin, causing the bottom material to form an arch bridge and the feeder to run idle. Each plate and frame of the bin is emptied once, and the material adhering to the bottom of the bin, the broken arch, and the feeder is cleared, so that the feeding speed of the bin is consistent each time and is continuously maintained at about 500 kg per hour, so that the feeding of the solid material bin to the disk dryer is kept smooth, thereby making the BET of the ternary precursor stable.

[0033] The following is a detailed description of the method for improving the BET of a ternary precursor by filter press unloading provided by the present invention through examples and comparative examples.

[0034] Example

[0035] Three production lines of the same model were selected for trial operation. The feed pressure of the filter press was 0.15Mpa. According to the wear and tear of the new and old pumps, the feed pressure of the diaphragm pump was adjusted between 0.5-0.6Mpa, so that the feed time was maintained at approximately 70-80 minutes. The liquid level was controlled in accordance with the principle of "the material in the slurry tank should be processed first". The processing time of each plate and frame was approximately 2 hours and 30 minutes, which basically matched the feeding time of the silo. Combined with the preparation time of 5-10 minutes and the unloading time of about 20 minutes, it can meet the requirement of processing one plate and frame material in 3 hours, ensuring that the silo does not accumulate more than one plate and frame material. The BET changes of the ternary precursor prepared in this embodiment are shown in the figure. Figure 2 shown.

[0036] Comparative Example 1

[0037] Two production lines were also selected for comparative experimental observation:

[0038] The feeding time of the filter press in this comparative example is about 90 minutes. Following the principle of "the material in the slurry tank should be processed first", the processing time of each plate frame is about 3.5 hours. After the material is processed, it is directly unloaded into the silo. The silo is emptied every 12 hours. The average feeding time of the silo is 3.5 hours. The BET changes of the ternary precursor prepared in this comparative example are as follows Figure 2 shown.

[0039] Comparative Example 2

[0040] The feeding time of the filter press is about 90 minutes. Following the principle of "the material in the slurry tank should be processed first", the processing time of each plate frame is about 3 hours. After the material is processed, it is directly unloaded into the silo without emptying the silo. It is found that the feeding time gradually increases and even the silo material forms an arch bridge. The feeding speed of the feeder is affected and even idling affects the material feeding. The material accumulates in the silo for a long time, which increases the BET of the product. The BET changes of the ternary precursor prepared in this comparative example are as follows Figure 2 shown.

[0041] See also Figure 2 By comparing the BET changes of the ternary precursors prepared in the embodiment of the present invention and the two comparative examples, it can be seen that the BET fluctuation range of the ternary precursor prepared in the embodiment of the present invention is between 8.82-9.55, while the BET fluctuation range of the ternary precursor prepared in comparative example 1 is between 8.94-10.37, and the BET fluctuation range of the ternary precursor prepared in comparative example 2 is between 8.55-10.12.

[0042] It can be seen from this that the BET fluctuation range of the ternary precursor prepared in the embodiment of the present invention is significantly smaller than the BET fluctuation range of the ternary precursor prepared in the two comparative examples. Therefore, the method of improving the BET of the ternary precursor by filter press unloading provided by the present invention is beneficial to making the BET consistency of the prepared ternary precursor better by stabilizing the feeding time and controlling the plate and frame unloading speed, and can reduce the occurrence of stratification.

[0043] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for improving the BET of a ternary precursor by filter press unloading, characterized in that: include: The ternary precursor material is aged, washed, pressed and purged in the plate and frame filter press and then enters the wet material bin, then enters the disc dryer for drying, then enters the mixer for mixing, and finally is sieved by the screening machine and packaged to obtain the ternary precursor; By regulating the pressure of the pneumatic diaphragm pump and the plate and frame feed pressure, the feed time difference of the 3rd, 4th and 11th 55C model experimental production lines of the plate and frame filter press was controlled to be 60±10 minutes; The feed level of the plate and frame filter press is controlled at 80% ± 10% to ensure that the slurry tank of the production line can be pumped empty every time; When handling materials, follow the principle of handling the materials in the most advanced slurry tank first; The time for the plate and frame filter press to process one plate and frame material is controlled at 160-165 minutes; After the materials in the plate and frame filter press are aged, washed, pressed and purged, the wet material bin and the plate and frame filter press are inspected before entering the wet material bin; The time it takes for the plate and frame filter press to unload a plate and frame of material is controlled within 15-20 minutes.

2. The method for improving the BET of a ternary precursor by filter press discharge according to claim 1, characterized in that: The pressure of the pneumatic diaphragm pump is controlled to be 0.5-0.6 MPa, and the plate and frame feed pressure is controlled to be 0.12-0.15 MPa.

3. The method for improving the BET of a ternary precursor by filter press discharge according to claim 1, characterized in that: The inspection of the wet material bin and the plate and frame filter press includes first checking the material level of the wet material bin to ensure that there is no material in the wet material bin, and then checking that the plate and frame filter press belt has no liquid accumulation, no alkali stains, and no oil stains, and that the pressing pressure and feed pressure of the plate and frame filter press are returned to zero.

4. The method for improving the BET of a ternary precursor by filter press discharge according to claim 1, characterized in that: The drying temperature of the disc dryer is controlled at 100-150°C.

5. The method for improving the BET of a ternary precursor by filter press discharge according to claim 1, characterized in that: The operating frequency of the mixer is 15-25 Hz, and the mixing time of the ternary precursor materials in the mixer is 25-35 minutes.

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