A cleaning method for a lithium iron manganese phosphate production device

Abstract

The present application relates to a kind of cleaning methods of lithium iron manganese phosphate production equipment, mainly using suitable concentration of citric acid as cleaning fluid for cleaning.Citric acid does not contain Cl ‑ , therefore will not cause corrosion to metal equipment;At the same time, citric acid can complex Fe 3+ , weaken the promoting effect of Fe 3+ Corrosion to metal equipment;By reasonable cleaning process parameter control, especially by using high concentration of citric acid, the paste wall phenomenon can be greatly weakened, which is beneficial to the rapid cleaning of pipeline, and also effectively saves the amount of pure water and power consumption;The inner wall of lithium iron manganese phosphate production equipment cleaned by the method of the present application is clean and bright, without impurity residue, and the waste liquid of citric acid cleaning is easy to handle, basically harmless to the environment, and safe and reliable for personnel operation.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of cleaning equipment in the industrial production of lithium battery electrode materials, and particularly relates to a cleaning method for a lithium iron manganese phosphate production equipment. BACKGROUND

[0002] Lithium iron manganese phosphate is a new type of lithium ion battery cathode material, which has the advantages of high energy density, long service life, good safety, etc., and has become an important part of the new generation of green energy storage devices. The production process of lithium iron manganese phosphate includes raw material preparation, mixing, ball milling, drying, sintering, powder grinding, and screening. The main raw materials of lithium iron manganese phosphate are manganese oxide, iron phosphate, lithium carbonate, etc.

[0003] In the production process of the prior art, there is a phenomenon of slurry sticking to the wall during the premixing and coarse and fine grinding of lithium iron manganese phosphate. After the coarse and fine grinding is completed, if the premixing tank and the coarse and fine grinding machine are not cleaned in time, the slurry will stick to the wall due to drying. In the prior art, pure water is mainly used for cleaning, but the residual lithium iron manganese phosphate slurry on the pipe wall cannot be effectively removed, and the phenomenon of drying and sticking to the wall still occurs. Moreover, for the sand grinding system, the dried powder will block the sand grinding filter screen, which needs to be disassembled and cleaned, causing waste of manpower and material resources and seriously affecting the production efficiency. SUMMARY

[0004] To solve the above problems, the purpose of the present application is to provide a cleaning method for a lithium iron manganese phosphate production equipment, which mainly uses citric acid with a suitable concentration as a cleaning liquid for cleaning, and then uses clean water for rinsing. Since citric acid does not contain Cl - , it will not cause corrosion to metal equipment; at the same time, citric acid can complex Fe 3+ , which weakens the corrosion of Fe 3+ to metal equipment; through reasonable control of cleaning process parameters, especially by using high-concentration citric acid, the slurry sticking phenomenon can be greatly reduced, which is beneficial to the rapid cleaning of the pipeline and also effectively saves the amount of pure water and power consumption; the inner wall of the lithium iron manganese phosphate production equipment cleaned by the method of the present application is clean and bright without impurities, and the waste liquid from citric acid cleaning is easy to treat, has little damage to the environment, and is safe and reliable for personnel to operate.

[0005] The cleaning method for a lithium iron manganese phosphate production equipment of the present application comprises using a citric acid aqueous solution with a mass concentration of 5%-25% as a cleaning liquid to clean the lithium iron manganese phosphate production equipment; and the citric acid aqueous solution flows through a mixing tank, a coarse grinding machine, and a fine grinding machine in sequence for cleaning.

[0006] Further, the cleaning method of the present application specifically comprises the following steps:

[0007] Step 1) sequentially add pure water and citric acid powder into the tank body of the mixing tank to form a first cleaning solution of a citric acid aqueous solution with a mass concentration of 5%-25%; open the stirring device of the mixing tank to stir and clean, and the stirring speed of the stirring device is set to 20-40 rpm / min; then, open the homogenizing pump of the mixing tank, and simultaneously perform the circulating cleaning of the pipeline of the mixing tank; the total cleaning time of the mixing tank is set to 20-40 min, and a second cleaning solution is obtained;

[0008] The second cleaning solution is a mixed cleaning solution of a citric acid aqueous solution with a mass concentration of 5%-20% and a slurry mixed aqueous solution;

[0009] Step 2) after the cleaning of the mixing tank is completed, open the valve connected to the transfer tank of the coarse grinder to allow the second cleaning solution to enter the transfer tank of the coarse grinder, and the rotating speed of the coarse grinder is set to 30-60 rpm / min for cleaning; then, open the diaphragm pump of the coarse grinder, and the frequency of the diaphragm pump of the coarse grinder is set to 0.5-1 Hz; perform the circulating cleaning of the coarse grinder, and the total cleaning time of the coarse grinder is set to 10-20 min to obtain a third cleaning solution;

[0010] The third cleaning solution is a mixed cleaning solution of a citric acid aqueous solution with a mass concentration of 5%-10% and a slurry mixed aqueous solution;

[0011] Step 3) after the cleaning of the coarse grinder is completed, open the valve connected to the transfer tank of the fine grinder to allow the third cleaning solution to enter the transfer tank of the fine grinder, and control the rotating speed of the fine grinder to be set to 40-65 rpm / min; then, open the diaphragm pump of the fine grinder, and the frequency of the diaphragm pump of the fine grinder is set to 0.3-0.6 Hz; perform the circulating cleaning of the fine grinder, and the total cleaning time of the fine grinder is set to 10-30 min;

[0012] Step 4) after the cleaning of the fine grinder is completed, the final cleaning solution is discharged into a sewage sedimentation tank for recycling.

[0013] In the principle of economic efficiency, it is expected to obtain the highest cleaning effect under the condition of the least use of citric acid. If the concentration of citric acid is higher than 25%, on the one hand, the high acidic condition has a corrosion effect on the inner walls of the tanks and the pipelines; on the other hand, too much citric acid will cause the cost to rise. If the concentration of citric acid is too low, the cleaning effect is not ideal.

[0014] In step 1), if the rotation speed of the mixing tank is set to be more than 40 rpm / min, the vibration amplitude of the equipment increases, and the service life of the equipment is damaged. If the rotation speed is too low, the cleaning effect is not good, and the cleaning of the inner wall of the equipment mainly depends on the rotation of the stirring paddle to drive the water solution to float and wash the inner wall of the tank. In step 2), if the rotation speed of the coarse grinder is higher than 60 rpm / min, the energy consumption of the equipment increases, and the friction between the zirconium beads in the grinding cavity of the coarse grinder increases, which accelerates the wear of the zirconium beads. If the rotation speed is lower than 30 rpm / min, the rotation amplitude of the zirconium beads in the grinding cavity of the coarse grinder is low, which is not conducive to the cleaning effect. In step 3), if the rotation speed of the fine grinder is higher than 65 rpm / min, the energy consumption of the equipment increases, and the friction between the zirconium beads in the grinding cavity of the fine grinder increases, which accelerates the wear of the zirconium beads. If the rotation speed is lower than 40 rpm / min, the rotation amplitude of the zirconium beads in the grinding cavity of the fine grinder is low, which is not conducive to the cleaning effect.

[0015] Further, the cleaning method of the present application further comprises step 5), which is to flush the mixing tank, the coarse grinder and the fine grinder with water for 1-3 times after the cleaning with the citric acid aqueous solution.

[0016] Further, in the cleaning method of the present application, the concentration of Fe 3+ in the second cleaning solution is 1wt%-3wt%. If the concentration of Fe 3+ is too high, we can add an appropriate amount of 5%-25% citric acid aqueous solution to adjust the concentration of Fe 3+ in the second cleaning solution to maintain 1wt%-3wt%.

[0017] Further, in the cleaning method of the present application, the concentration of Fe 3+ in the third cleaning solution is 3wt%-5wt%. If the concentration of Fe 3+ is too high, we can add an appropriate amount of 5%-25% citric acid aqueous solution to adjust the concentration of Fe 3+ in the third cleaning solution to maintain 3wt%-5wt%.

[0018] Further, in the cleaning method of the present application, the stirring speed of the stirring device in step 1) is set to 28-35 rpm / min, and the homogenizing pump of the mixing tank is opened after cleaning for 8-15 min.

[0019] Further, in the cleaning method of the present application, the rotation speed of the coarse grinder in step 2) is set to 30-60 rpm / min, and the diaphragm pump of the coarse grinder is opened for circulating cleaning after cleaning for 5-10 min, and the frequency of the diaphragm pump of the coarse grinder is set to 0.8-1 Hz.

[0020] Further, in the cleaning method, the rotation speed of the fine grinder is set to 55-65 rpm / min, and the frequency of the diaphragm pump of the fine grinder is set to 0.5-0.6 Hz.

[0021] Compared with the prior art, the present application has the following beneficial technical effects:

[0022] The cleaning method of the lithium iron manganese phosphate production equipment has the advantages that the citric acid does not contain Cl-, so it does not corrode the metal equipment; meanwhile, the citric acid can complex Fe 3+ , which weakens the corrosion of Fe 3+ on the metal equipment; through reasonable control of the cleaning process parameters, especially through the use of high-concentration citric acid, the slurry wall sticking phenomenon can be greatly weakened, which is beneficial to the rapid cleaning of the pipeline and also effectively saves the amount of pure water and the power consumption; after being cleaned by the cleaning method, the inner wall of the lithium iron manganese phosphate production equipment is clean and bright, and no impurities are left, and the waste liquid generated by the citric acid cleaning is easy to treat, has little damage to the environment, and is safe and reliable for personnel to operate. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the technical scheme in the embodiments of the present application will be clearly and completely described below. Unless otherwise specified, the specific conditions in the embodiments are carried out according to the conventional conditions or the conditions recommended by the manufacturer. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as understood by those skilled in the art.

[0024] The cleaning method of the lithium iron manganese phosphate production equipment comprises using a citric acid aqueous solution with a mass concentration of 5%-25% as a cleaning liquid to clean the lithium iron manganese phosphate production equipment; and the citric acid aqueous solution is sequentially circulated and cleaned in the mixing tank, the coarse grinder and the fine grinder.

[0025] In accordance with the principle of economic efficiency, it is expected to obtain the highest cleaning effect under the condition of using the least citric acid. If the concentration of citric acid is higher than 25%, on the one hand, the high acidity has a corrosive effect on the inner walls of the tanks and the pipeline; on the other hand, too much citric acid will increase the cost. If the concentration of citric acid is too low, the cleaning effect is not ideal.

[0026] In some embodiments, the cleaning method specifically comprises the following steps:

[0027] Step 1) sequentially add pure water and citric acid powder into the tank body of the mixing tank to form a first cleaning solution of a citric acid aqueous solution with a mass concentration of 5%-25%; open the stirring device of the mixing tank for stirring and cleaning, and set the stirring speed of the stirring device to 20-40 rpm / min; then, open the homogenizing pump of the mixing tank, and simultaneously perform the circulating cleaning of the pipeline of the mixing tank; set the total cleaning time of the mixing tank to 20-40 min, and finally obtain a second cleaning solution;

[0028] The second cleaning solution is a mixed cleaning solution of a citric acid aqueous solution with a mass concentration of 5%-20% and a slurry mixed aqueous solution;

[0029] Step 2) after the cleaning of the mixing tank is completed, open the valve connected to the transfer tank of the coarse grinder to make the second cleaning solution enter the transfer tank of the coarse grinder, and set the rotating speed of the coarse grinder to 30-60 rpm / min for cleaning; then, open the diaphragm pump of the coarse grinder, and set the frequency of the diaphragm pump of the coarse grinder to 0.5-1 Hz; perform the circulating cleaning of the coarse grinder, and set the total cleaning time of the coarse grinder to 10-20 min to obtain a third cleaning solution;

[0030] The third cleaning solution is a mixed cleaning solution of a citric acid aqueous solution with a mass concentration of 5%-10% and a slurry mixed aqueous solution;

[0031] Step 3) after the cleaning of the coarse grinder is completed, open the valve connected to the transfer tank of the fine grinder to make the third cleaning solution enter the transfer tank of the fine grinder, and control the rotating speed of the fine grinder to be set to 40-65 rpm / min; then, open the diaphragm pump of the fine grinder, and set the frequency of the diaphragm pump of the fine grinder to 0.3-0.6 Hz; perform the circulating cleaning of the fine grinder, and set the total cleaning time of the fine grinder to 10-20 min;

[0032] Step 4) after the cleaning of the fine grinder is completed, discharge the final cleaning solution into a sewage sedimentation tank for recycling.

[0033] In step 1), if the rotation speed of the mixing tank is set to be more than 40 rpm / min, the vibration amplitude of the equipment increases, and the service life of the equipment is damaged. If the rotation speed is too low, it is not conducive to the cleaning effect. The cleaning of the inner wall of the equipment mainly relies on the rotation of the stirring paddle to drive the water solution to float and scour the inner wall of the tank. In step 2), if the rotation speed of the coarse grinder is higher than 60 rpm / min, the energy consumption of the equipment increases, and the friction between the zirconium beads in the grinding cavity of the coarse grinder increases, accelerating the wear of the zirconium beads. If the rotation speed is lower than 30 rpm / min, the rotation amplitude of the zirconium beads in the grinding cavity of the coarse grinder is low, which is not conducive to the cleaning effect. In step 3), if the rotation speed of the fine grinder is higher than 65 rpm / min, the energy consumption of the equipment increases, and the friction between the zirconium beads in the grinding cavity of the fine grinder increases, accelerating the wear of the zirconium beads. If the rotation speed is lower than 40 rpm / min, the rotation amplitude of the zirconium beads in the grinding cavity of the fine grinder is low, which is not conducive to the cleaning effect.

[0034] In some embodiments, the cleaning method further comprises step 5) of rinsing the mixing tank, the coarse grinder and the fine grinder with water for 1-3 times after the citric acid aqueous solution cleaning is completed.

[0035] In some embodiments, the concentration of Fe3+ in the second cleaning solution is 1wt%-3wt%. 3+

[0036] In some embodiments, if the concentration of Fe3+ is too high, we can add an appropriate amount of 5%-25% citric acid aqueous solution to adjust the concentration of Fe3+ in the second cleaning solution to maintain 1wt%-3wt% without affecting the cleaning effect.

[0037] In some embodiments, the concentration of Fe3+ in the third cleaning solution is 3wt%-5wt%. 3+

[0038] In some embodiments, if the concentration of Fe3+ is too high, we can add an appropriate amount of 5%-25% citric acid aqueous solution to adjust the concentration of Fe3+ in the third cleaning solution to maintain 3wt%-5wt% without affecting the cleaning effect.

[0039] In some embodiments, the stirring speed of the stirring device in step 1) is set to 28-35 rpm / min, and after cleaning for 8-15 min, the homogenizer pump of the mixing tank is opened.

[0040] In some embodiments, the rotation speed of the coarse grinder in step 2) is set to 30-60 rpm / min, and after cleaning for 5-10 min, the diaphragm pump of the coarse grinder is opened for circulating cleaning, and the frequency of the diaphragm pump of the coarse grinder is set to 0.8-1 Hz.

[0041] ​​In some embodiments, the rotation speed of the fine grinder in step 3) is set to 55-65 rpm / min, and the frequency of the diaphragm pump of the fine grinder is set to 0.5-0.6 Hz.

[0042] The application will be further described in detail below with reference to specific examples.

[0043] Example 1

[0044] The cleaning method of the lithium manganese iron phosphate production equipment provided in this example includes using a citric acid aqueous solution with a mass concentration of 5%-25% as a cleaning liquid to clean the lithium manganese iron phosphate production equipment; and the citric acid aqueous solution is sequentially subjected to circulating cleaning in a mixing tank, a coarse grinder and a fine grinder.

[0045] The cleaning method specifically includes the following steps:

[0046] Step 1) A cleaning liquid of a citric acid aqueous solution with a mass concentration of 5%-25% is formed by sequentially adding pure water and citric acid powder into the tank body of the mixing tank; the stirring device of the mixing tank is opened for stirring cleaning, and the stirring speed of the stirring device is set to 20-40 rpm / min; then, the homogenizing pump of the mixing tank is opened, and the circulating cleaning of the pipeline of the mixing tank is simultaneously performed; the total cleaning time of the mixing tank is set to 20-40 min, and a second cleaning liquid is finally obtained.

[0047] The second cleaning liquid is a mixed cleaning liquid of a citric acid aqueous solution with a mass concentration of 5%-20% and a slurry mixed aqueous solution; the concentration of Fe 3+ in the second cleaning liquid is 1wt%-3wt%.

[0048] Step 2) After the cleaning of the mixing tank is completed, the valve of the transfer tank connected to the coarse grinder is opened, so that the second cleaning liquid enters the transfer tank of the coarse grinder, and the rotation speed of the coarse grinder is set to 30-60 rpm / min for cleaning; then, the diaphragm pump of the coarse grinder is opened, and the frequency of the diaphragm pump of the coarse grinder is set to 0.5-1 Hz; the circulating cleaning of the coarse grinder is performed, and the total cleaning time of the coarse grinder is set to 10-20 min, so as to obtain a third cleaning liquid.

[0049] The third cleaning liquid is a mixed cleaning liquid of a citric acid aqueous solution with a mass concentration of 5%-10% and a slurry mixed aqueous solution; the concentration of Fe 3+ in the third cleaning liquid is 3wt%-5wt%.

[0050] Step 3) After the completion of the cleaning of the coarse grinder, open the valve of the transfer tank connected to the fine grinder, and let the third cleaning liquid into the transfer tank of the fine grinder. The rotation speed of the fine grinder is set to 40-65 rpm / min. Then, open the diaphragm pump of the fine grinder, and set the frequency of the diaphragm pump of the fine grinder to 0.3-0.6 Hz. The circulating cleaning of the fine grinder is performed, and the total cleaning time of the fine grinder is set to 10-20 min.

[0051] Step 4) After the completion of the cleaning of the fine grinder, the final cleaning liquid is completely discharged into the sewage sedimentation tank for recovery treatment.

[0052] Step 5) After the completion of the cleaning of the citric acid aqueous solution, the mixing tank, the coarse grinder, and the fine grinder are sequentially rinsed twice with pure water.

[0053] Example 2

[0054] The difference between this example 2 and example 1 is that the first cleaning liquid is a citric acid aqueous solution with a mass concentration of 20%.

[0055] Example 3

[0056] The difference between this example 3 and example 1 is that the first cleaning liquid is a citric acid aqueous solution with a mass concentration of 18%.

[0057] Example 4

[0058] The difference between this example 4 and example 1 is that the first cleaning liquid is a citric acid aqueous solution with a mass concentration of 10%.

[0059] Example 5

[0060] The difference between this example 5 and example 1 is that the first cleaning liquid is a citric acid aqueous solution with a mass concentration of 25%.

[0061] Example 6

[0062] The difference between this example 6 and example 1 is that the stirring rotation speed of the stirring device in step 1) is set to 20 rpm / min.

[0063] Example 7

[0064] The difference between this example 7 and example 1 is that the stirring rotation speed of the stirring device in step 1) is set to 20 rpm / min, and the homogenizing pump of the mixing tank is opened after 8 min of cleaning.

[0065] Example 8

[0066] The embodiment 8 is different from the embodiment 1 only in that the stirring speed of the stirring device in step 1) is set to 28 rpm / min, and the homogenizing pump of the mixing tank is opened after cleaning for 8 min; the speed of the coarse grinder in step 2) is set to 30 rpm / min, and the diaphragm pump of the coarse grinder is opened for circulating cleaning after cleaning for 10 min, and the frequency of the diaphragm pump of the coarse grinder is set to 0.8 Hz.

[0067] Comparative example 1:

[0068] The comparative example 1 is different from the embodiment 2 only in that the first cleaning liquid is pure water.

[0069] Comparative example 2:

[0070] The comparative example 2 is different from the embodiment 4 only in that the first cleaning liquid is a citric acid aqueous solution with a mass concentration of 3%.

[0071] Comparative example 3:

[0072] The comparative example 3 is different from the embodiment 5 only in that the first cleaning liquid is a citric acid aqueous solution with a mass concentration of 40%.

[0073] After the cleaning of the above-mentioned embodiments 1-8 is completed, the inner wall of the lithium manganese iron phosphate production equipment is clean and bright, and no impurity residue is left, and the pure water consumption and power consumption are effectively saved; in addition, the waste liquid of citric acid cleaning is easy to treat, and has basically no damage to the environment, and the personnel operation is safe and reliable. After the cleaning of the above-mentioned comparative examples 1-3 is completed, the inner wall of the lithium manganese iron phosphate production equipment has a residual slurry sticking phenomenon, and the lithium manganese iron phosphate slurry is left on the pipe wall, and the sanding filter screen of the coarse grinder and the fine grinder still needs to be cleaned.

[0074] The above-mentioned specific embodiments further specifically describe the purposes, technical solutions and beneficial effects of the present application, and it should be understood that the above-mentioned embodiments are only specific embodiments of the present application, and are not used to limit the protection scope of the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A cleaning method of a lithium iron manganese phosphate production apparatus, characterized by, The cleaning method comprises using a citric acid aqueous solution with a mass concentration of 5%-25% as a cleaning liquid to clean the lithium iron manganese phosphate production equipment; the citric acid aqueous solution sequentially flows through a mixing tank, a coarse grinder and a fine grinder for cleaning; The cleaning method specifically comprises the following steps: Step 1) adding pure water and citric acid powder into the tank body of the mixing tank in sequence to form a first cleaning liquid of the citric acid aqueous solution with a mass concentration of 5%-25%; opening a stirring device of the mixing tank for stirring and cleaning, and setting the stirring speed of the stirring device to 20-40 rpm / min; then, opening a homogenizing pump of the mixing tank, and simultaneously performing the circulating cleaning of the pipeline of the mixing tank; setting the total cleaning time of the mixing tank to 20-40 min, and finally obtaining a second cleaning liquid; the second cleaning liquid is a mixed cleaning liquid of the citric acid aqueous solution with a mass concentration of 5%-20% and a slurry mixed aqueous solution; Step 2) after the cleaning of the mixing tank is completed, opening a valve connected to a transfer tank of the coarse grinder to make the second cleaning liquid enter the transfer tank of the coarse grinder, setting the rotating speed of the coarse grinder to 30-60 rpm / min for cleaning; then, opening a diaphragm pump of the coarse grinder, and setting the frequency of the diaphragm pump of the coarse grinder to 0.5-1 Hz; performing the circulating cleaning of the coarse grinder, and setting the total cleaning time of the coarse grinder to 10-20 min to obtain a third cleaning liquid; the third cleaning liquid is a mixed cleaning liquid of the citric acid aqueous solution with a mass concentration of 5%-10% and the slurry mixed aqueous solution; Step 3) after the cleaning of the coarse grinder is completed, opening a valve connected to a transfer tank of the fine grinder to make the third cleaning liquid enter the transfer tank of the fine grinder, and setting the rotating speed of the fine grinder to 40-65 rpm / min; then, opening a diaphragm pump of the fine grinder, and setting the frequency of the diaphragm pump of the fine grinder to 0.3-0.6 Hz to perform the circulating cleaning of the fine grinder; and setting the total cleaning time of the fine grinder to 10-20 min; Step 4) after the cleaning of the fine grinder is completed, discharging the final cleaning liquid into a sewage sedimentation tank for recycling treatment; And Fe in the second cleaning solution 3+ The concentration of Fe in the third cleaning solution is 1wt%-3wt%; 3+ The concentration is 3wt%-5wt%.

2. The cleaning method according to claim 1, characterized by, The cleaning method further comprises Step 5) that after the cleaning of the citric acid aqueous solution is completed, using water to flush the mixing tank, the coarse grinder and the fine grinder in sequence for 1-3 times.

3. The cleaning method according to claim 2, characterized by, In Step 1), the stirring speed of the stirring device is set to 28-35 rpm / min, and after cleaning for 8-15 min, the homogenizing pump of the mixing tank is opened.

4. The cleaning method according to claim 3, characterized by, In Step 2), the rotating speed of the coarse grinder is set to 30-60 rpm / min, and after cleaning for 5-10 min, the diaphragm pump of the coarse grinder is opened for the circulating cleaning, and the frequency of the diaphragm pump of the coarse grinder is set to 0.8-1 Hz.

5. The cleaning method according to claim 4, wherein In Step 3), the rotating speed of the fine grinder is set to 55-65 rpm / min, and the frequency of the diaphragm pump of the fine grinder is set to 0.5-0.6 Hz.