JP7167506B2 - Filtration device, filtration method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a filtering device and a filtering method.

Various methods for synthesizing powders are known, and a wet method in which raw materials are reacted in a solvent for synthesis is one of the main synthesis methods.

In the wet method, a solid-liquid separation step for separating powder and liquid is often required to finally obtain powder. Examples of solid-liquid separation methods used in the solid-liquid separation step include sedimentation, vacuum filtration, pressure filtration, and centrifugation.

A filter press is a type of pressure filtration machine, and it is possible to filter slurry and wash the cake by supplying washing water to the cake after filtration and filtering again. Conventionally, it has been widely used industrially as a filtering means of an apparatus (see, for example, Patent Document 1).

JP 2011-230958 A

However, according to the conventional filtration apparatus equipped with a filter press, the components remaining in the cake obtained after filtration by the filter press may vary from batch to batch. In addition, depending on the application, the obtained cake and the performance of chemical products obtained from the cake are unstable, which is a problem.

In view of the problems of the prior art, an object of one aspect of the present invention is to provide a filtering device capable of suppressing variations in components remaining in the obtained cake.

In order to solve the above problems, in one aspect of the present invention,
filter press and
Slurry concentration measuring means for measuring the concentration of solid components in the slurry, arranged in a slurry supply pipe to the filter press;
Filtrate concentration measuring means for measuring the concentration of solid components in the filtrate, arranged in a pipe for discharging the filtrate from the filter press;
Based on the concentration of the solid component in the slurry measured by the slurry concentration measuring means, the slurry filling amount, which is the amount of the solid component in the slurry filled in the filter press, is calculated, and the filtrate concentration measuring means and a control/calculation means for correcting the slurry filling amount based on the measured concentration of solid components in the filtrate .

ADVANTAGE OF THE INVENTION According to one aspect of the present invention, it is possible to provide a filtering device capable of suppressing variations in components remaining in the resulting cake.

Explanatory drawing of the filtration apparatus which concerns on embodiment of this invention.

An embodiment of the filtering device and the filtering method of the present invention will be described below.
[Filtration device]
The filtration apparatus of this embodiment can have a filter press and slurry concentration measuring means for measuring the concentration of solid components in the slurry, which is arranged in a slurry supply pipe to the filter press.

The inventors of the present invention have found that in a filtration device equipped with a conventional filter press, the We investigated the cause of batch-to-batch variations in the components remaining in the cake.

Then, the extent to which the liquid component remains in the cake obtained by the filtration device equipped with the filter press, and the slurry filling amount (hereinafter referred to as " We paid attention to the fact that it depends on the amount of slurry charged").

In a conventional filter press equipped with a filter press, the slurry filling amount is controlled by the slurry concentration, slurry flow rate, and slurry feeding time in the slurry undiluted tank before the start of filtration. However, before starting filtration, for example, immediately after slurry preparation, the slurry concentration of the slurry stored in the slurry undiluted solution tank is measured by a hydrostatic sedimentation method, apparent viscosity measurement, Nutsche filtration / drying method, etc., and the slurry before the start of filtration The slurry concentration in the stock solution tank was used continuously throughout the filtration operation. The slurry concentration means the concentration of solid components in the slurry. Hereinafter, the slurry concentration has the same meaning in this specification.

However, the slurry concentration changes even after the start of supplying the slurry due to the fact that the water from backwashing the filter cloth of the filter press returns to the slurry undiluted solution tank. For this reason, in a filtration device equipped with a conventional filter press, it was not possible to accurately evaluate the slurry concentration of the slurry when it was supplied to the filter press. was occurring. Then, they found that the components remaining in the cake obtained as a result also varied, and completed the present invention.

The filtering device of this embodiment will be described below with reference to the drawings.

FIG. 1 is a diagram schematically showing a configuration example of a filtering device 10 of this embodiment. As shown in FIG. 1, the filtration device 10 of this embodiment has a supply pipe 12 that supplies slurry to a filter press 11, and one end 12a of the supply pipe 12 is connected to the filter press 11. The other end 12b is connected to a slurry supply means 13 for supplying slurry to the supply pipe 12. As shown in FIG. A slurry concentration measuring means 14 capable of measuring the slurry concentration of the slurry flowing through the supply pipe 12 is arranged on the supply pipe 12 .

The configuration of the filter press 11 is not particularly limited, and can be arbitrarily selected according to the type of slurry to be supplied, details of operation, and the like. For example, one or more types of filter press selected from a plate frame type pressure filter, a concave plate type pressure filter and the like can be used.

In the filter press 11, after the slurry is filled, it is filtered (solid-liquid separation) to obtain a cake, or a washing liquid such as pure water is supplied to the obtained cake, and then filtered again (solid-liquid separation). By doing so, the cake can also be washed. The filter press 11 can optionally be connected to drying means for drying the cake obtained, for example.

The supply pipe 12 is not particularly limited as long as it can supply slurry from the slurry supply means 13 to the filter press 11, and various pipes can be used.

The slurry supply means 13 is not particularly limited as long as it can supply slurry to the supply pipe 12 . Devices constituting the slurry supply means 13 include, for example, a slurry undiluted solution tank in which slurry is stored, a reaction tank in which slurry is generated, and the like. The slurry supply means 13 can also be composed of a plurality of devices, for example, it is composed of a reaction tank for generating slurry and a slurry raw liquid tank for storing the slurry generated in the reaction tank, and the slurry raw liquid tank is connected to a supply pipe. 12 can also be configured.

A slurry concentration measuring means 14 can be arranged in the supply pipe 12 . It should be noted that disposing the slurry concentration measuring means 14 in the supply pipe 12 means disposing the slurry concentration measuring means at any position on the supply pipe 12 so that the slurry concentration of the slurry flowing in the supply pipe 12 can be measured. means that

The slurry concentration measuring means 14 is not particularly limited as long as it can measure the slurry concentration of the slurry flowing through the supply pipe 12 in-line. As the slurry concentration measuring means, it is preferable to use one or more selected from a fluorescent X-ray device, a transmission X-ray measuring device, a slurry concentration measuring device using a differential pressure method, a turbidity meter, an ultrasonic measuring device, and the like.

The fluorescent X-ray device and the transmitted X-ray measuring device irradiate the slurry flowing in the supply pipe 12 with X-rays generated from the X-ray generator, and the fluorescent X-rays generated in the supply pipe 12 or the transmitted X-rays It is a device for detecting transmitted X-rays. When a fluorescent X-ray device or a transmission X-ray device is used as a slurry concentration measuring means, the slurry flowing in the supply pipe 12 is irradiated with X-rays, the intensity of the detected fluorescent X-rays or transmitted X-rays, and the The slurry concentration can be calculated from the previously set calibration curve showing the relationship between the intensity of fluorescent X-rays or transmitted X-rays and the slurry concentration.

Slurry concentration measurement equipment using the differential pressure method is based on the fact that the pressure generated in the slurry increases greatly in the depth direction due to the weight of the slurry, and the higher the slurry concentration, the greater the amount of solid components in the material contained in the slurry. This is a measuring device that utilizes the fact that the specific gravity of slurry increases. When a slurry concentration measuring device using a differential pressure method is used as a slurry concentration measuring means, part of the slurry flowing in the supply pipe 12 is sampled and continuously circulated at a constant flow rate through a circulation pipe having a height difference. Measure the differential pressure of the circulating slurry between the lowest and highest points of the pipe. Then, the slurry concentration can be calculated from the measured differential pressure and a previously created calibration curve showing the relationship between the differential pressure and the slurry concentration.

As a turbidity meter, a transmitted scattered light method, a surface scattered light method, an integrating sphere method, a transmitted light method, a scattered light method, a particle counting method, etc. are known. can be When a turbidity meter is used as a slurry concentration measuring means, the turbidity of the slurry flowing in the supply pipe 12 measured by the turbidity meter and the calibration curve showing the relationship between the turbidity and the slurry concentration prepared in advance Slurry concentration can be calculated.

The ultrasonic measurement device is a device that applies ultrasonic waves to the slurry passing through the supply pipe and measures reflected or transmitted ultrasonic waves. When an ultrasonic measuring device is used as a slurry concentration measuring means, the slurry flowing in the supply pipe 12 is irradiated with ultrasonic waves, and the intensity of the reflected or transmitted ultrasonic waves measured and the intensity of the ultrasonic waves generated in advance. and the calibration curve showing the relationship between the slurry concentration and the slurry concentration can be calculated.

In particular, the slurry concentration measuring means is more preferably one or more selected from a turbidity meter and an ultrasonic measuring device. This is because a turbidity meter or an ultrasonic measuring device shows a linear response to the slurry concentration, so that the slurry concentration can be measured easily and accurately, and the cost is low.

Although the unit of the slurry concentration is not particularly limited, it is preferable that the slurry filling amount calculated using the slurry concentration is represented by the mass of the solid content such as g or kg. For this reason, the slurry concentration is preferably represented by mass of solid content per unit volume of slurry, such as g/L, g/m ³ , kg/L.

In addition, it is not necessary to arrange all the members of the slurry concentration measuring means in the supply pipe 12. For example, only the detection part is arranged, and the signal from the detection part is used to control, for example, the control/calculation means 16, etc., which will be described later. It is also possible to configure the slurry concentration to be calculated by a calculation unit or the like provided inside. Moreover, the slurry concentration measuring means is not limited to one measuring means, and may have a plurality of measuring means of the same method or different methods.

The timing for measuring the slurry concentration by the slurry concentration measuring means 14 is not particularly limited, and the measurement can be made at any timing. However, in order to more accurately grasp the concentration of the slurry flowing through the supply pipe 12, it is possible to measure the concentration of the slurry two or more times, that is, a plurality of times after starting the supply of the slurry to the filter press. preferable.

The filtering device of this embodiment can further have arbitrary members in addition to the members described above.

The filter device 10 of this embodiment can also have a valve 15 for controlling the amount of slurry supplied to the filter press 11, for example. The valve 15 may be configured to control the degree of opening by, for example, control/calculation means 16, which will be described later. Although FIG. 1 shows an example in which one valve is provided, the present invention is not limited to such a form, and a plurality of valves may be provided at arbitrary positions.

The filtering device 10 of this embodiment can also have a control/calculation means 16 . The control/calculation means 16 is configured to adjust the slurry supply amount and the slurry supply time based on, for example, the slurry concentration measured by the slurry concentration measurement means 14, and to control the slurry filling amount to the filter press 11. can. Specifically, for example, the control/calculation means 16 calculates the amount of slurry charged into the filter press 11 by multiplying the slurry concentration measured by the slurry concentration measurement means 14 and the integrated value of the slurry flow rate to the filter press 11. be able to. The slurry filling amount can also be calculated by a method such as calculating the slurry filling amount per unit time by multiplying the slurry concentration, the slurry flow rate (liquid feeding speed), and the unit time, for example, and integrating the results. Further, for example, the slurry filling amount can be calculated from the product of the slurry concentration, the flow velocity of the slurry, the cross-sectional area of the pipe, and the liquid feeding time.

In addition, when the slurry concentration is measured multiple times after the slurry supply to the filter press 11 is started and before the supply is completed, the slurry concentration is newly measured according to the timing of measurement and the timing of calculation. value and used to calculate the slurry fill amount. Also, the average value of the measured slurry concentrations can be used for calculation.

Then, the control/calculation means 16 can determine, for example, whether the slurry filling amount has reached a target value. can also be controlled to close the The control/calculation means 16 can also be configured to request the slurry concentration measurement means 14 to measure the slurry concentration at a predetermined timing. It should be noted that the control/calculation means 16 can be divided into a control means and a calculation means, and can be provided as a plurality of members.

For example, a flow meter (not shown) is also provided in the supply pipe 12, and the integrated value of the slurry flow rate or the flow rate of the slurry such as the slurry flow rate per unit time is also measured, and the slurry filling amount to the filter press 11 is more accurately determined. It is more preferable to configure so that it can be calculated to In this case, the control/calculation means 16 can also use the slurry flow rate calculated by the flow meter to calculate the slurry filling amount.

In addition, the filtration apparatus of the present embodiment may further include filtrate concentration measuring means 18 for measuring the concentration of solid components in the filtrate, in the filtrate discharge pipe 17 from the filter press 11 .

The filtrate discharged from the filter press 11 may also contain solid components. Therefore, a filtrate concentration measuring means 18 is arranged in the filtrate discharge pipe 17 connected to the filter press 11, the concentration of the solid components in the filtrate is measured, and the amount of the solid components flowed out by the filtrate is calculated. By performing a correction by subtracting the amount of the outflowing solid component from the slurry filling amount, the slurry filling amount can be calculated more accurately. When performing such correction, for example, as described above, when the control/calculation means 16 determines whether the slurry filling amount has reached the target value, the slurry filling amount after the above correction is used. be able to.

In addition, disposing the filtrate concentration measuring means 18 in the discharge pipe 17 means that the concentration of solid components in the filtrate flowing through the discharge pipe 17 can be measured at any position on the discharge pipe 17. It means that the filtrate concentration measuring means 18 is arranged in the .

The filtrate concentration measuring means 18 is not particularly limited as long as it can measure the concentration of solid components in the filtrate flowing through the discharge pipe 17 in-line. For example, as in the case of the above-described slurry concentration measuring means, one or more selected from fluorescent X-ray equipment, transmission X-ray measuring equipment, slurry concentration measuring equipment using differential pressure method, turbidity meter, ultrasonic measuring equipment, etc. is preferably used. Since these devices have already been described in the slurry concentration measuring device, their description is omitted here.

In particular, the filtrate concentration measuring means is more preferably one or more selected from turbidimeters and ultrasonic measuring devices. This is because a turbidity meter or an ultrasonic measuring device shows a linear response to the concentration of solid components in the filtrate, so that the solid concentration can be accurately measured and the cost is low. is.

The slurry concentration measuring means 14 and the filtrate concentration measuring means 18 may be the same type of measuring device, or may be different types of measuring devices.

Regarding the filtrate concentration measuring means 18, it is not necessary to arrange all the members of the filtrate concentration measuring means 18 in the discharge pipe 17. For example, it is also possible to configure such that the concentration of the solid component in the filtrate is calculated by a calculation section or the like provided inside the aforementioned control/calculation means 16 or the like.

When the filtrate concentration measuring means 18 is provided, for example, the control/calculating means 16 calculates the product of the concentration of the solid components in the filtrate measured by the filtrate concentration measuring means 18 and the integrated value of the flow rate of the filtrate. , the amount of solid components washed out by the filtrate can be calculated.

The method for calculating the amount of the solid component discharged by the filtrate is not limited to the above method, and can be calculated by various methods as in the case of the slurry filling amount. For example, by multiplying the concentration of the solid component in the measured filtrate, the flow rate of the filtrate (flow rate), and the unit time, the amount of the solid component flowing out of the filtrate per unit time is calculated and integrated. It is also possible to calculate the amount of the solid component discharged by the filtrate. Further, for example, the amount of the solid component discharged by the filtrate can be calculated by multiplying the concentration of the solid component in the filtrate, the flow rate of the filtrate, the cross-sectional area of the discharge pipe, and the liquid feeding time. .

After starting the supply of slurry to the filter press 11, when measuring the concentration of the solid component in the filtrate a plurality of times, the concentration of the solid component in the filtrate is determined according to the timing of measurement and the timing of calculation. It can be updated with newly measured values and used to calculate the amount of solid components washed out by the filtrate. In addition, the average value of the measured concentration of the solid components in the filtrate can also be used for the calculation.

The discharge pipe 17 may be provided with a flow meter or the like for measuring the flow rate and flow rate of the filtrate, if necessary.

Then, the control/calculation means 16 can calculate a more accurate slurry filling amount by performing a correction by subtracting the calculated amount of the solid component flowing out of the filtrate from the slurry filling amount.

In addition to the control/calculation means 16 for the slurry concentration measurement means 14 described above, a control/calculation means for the filtrate concentration measurement means may be provided to perform the above calculations and corrections.

The filtrate concentration measuring means is not limited to one measuring means, and may have a plurality of measuring means of the same method or different methods.

The timing for measuring the concentration of the solid component in the filtrate by the filtrate concentration measuring means 18 is not particularly limited, and the measurement can be made at any timing. However, in order to more accurately grasp the concentration of the solid components in the filtrate flowing through the discharge pipe 17, after starting slurry supply to the filter press, It is preferably configured to measure the concentration of solid components.

The type of slurry to be supplied to the filtration device of this embodiment is not particularly limited, and various slurries can be applied. However, it is preferable that the slurry is particularly required to suppress variations in the components remaining in the resulting cake.

According to studies by the inventors of the present invention, a positive electrode active material precursor used as a raw material for a positive electrode material for a lithium ion secondary battery can be produced, for example, by a crystallization method, and the obtained positive electrode active material precursor The positive electrode active material precursor is recovered by filtering the slurry containing the solids. Then, depending on the variation in the sulfate group contained in the positive electrode active material precursor for the lithium ion secondary battery and the chlorine group, the positive electrode active material prepared from the positive electrode active material precursor and the lithium ion secondary using it Battery performance may vary. Therefore, the slurry containing the positive electrode active material precursor for lithium secondary batteries can be preferably applied to the filtering device of the present embodiment and the filtering method described later, which can suppress variations in the components remaining in the cake.

In some cases, after producing a positive electrode active material from a positive electrode active material precursor for a lithium secondary battery, the positive electrode active material is dispersed in pure water to form a slurry, which is then filtered to wash the slurry. If the amount of metal ions remaining in the positive electrode active material recovered after the washing step varies, the performance of the lithium ion secondary battery using the positive electrode active material may vary. For this reason, the slurry containing the positive electrode active material for lithium ion secondary batteries can be preferably applied to the filtering device of the present embodiment and the filtering method described later, which can suppress variations in the components remaining in the cake.

According to the filtration apparatus of the present embodiment described above, since the slurry concentration measuring means is provided, it is possible to more accurately calculate the amount of slurry charged into the filter press. Therefore, it is possible to suppress variations in the components remaining in the cake obtained after filtration.
[Filtration method]
Next, the filtering method of this embodiment will be described.

The filtration method of the present embodiment is a filtration method of supplying slurry to a filter press and filtering the slurry by the filter press, and can have the following slurry filling amount calculation step.

The slurry concentration, which is the concentration of solid components in the slurry supplied to the filter press, is measured by means of a slurry concentration measuring means arranged in the slurry supply pipe to the filter press, and the slurry filled in the filter press is measured based on the slurry concentration. a slurry filling amount calculation step of calculating a slurry filling amount, which is the amount of solid components in the slurry;

The filtering method of this embodiment can be implemented using the filtering device described above. Therefore, some of the items already explained will be omitted.

The filtering method of this embodiment can be carried out using, for example, the filtering device 10 shown in FIG. Then, in the slurry filling amount calculation step, the slurry concentration of the slurry supplied from the slurry supply means 13 and passed through the supply pipe 12 is measured by the slurry concentration measurement means 14, and the slurry to the filter press 11 is supplied based on the measured slurry concentration. Fill volume can be calculated.

The slurry concentration measuring means 14 is not particularly limited, but as described above, a fluorescent X-ray device, a transmission X-ray measuring device, a slurry concentration measuring device using a differential pressure method, a turbidity meter, an ultrasonic It is preferable to use one or more types selected from measuring devices and the like. In particular, the slurry concentration measuring means is more preferably one or more selected from a turbidity meter and an ultrasonic measuring device.

In the slurry filling amount calculation step, the number and timing of measuring the slurry concentration by the slurry concentration measuring means 14 are not particularly limited, and the measurement can be performed at any timing and any number of times. However, in order to more accurately grasp the slurry concentration and particularly accurately calculate the amount of slurry to be charged, it is preferable to carry out, for example, two or more times after starting slurry supply to the filter press 11 .

Although the specific procedure for calculating the amount of slurry to be filled into the filter press 11 based on the measured slurry concentration is not particularly limited, for example, the amount of slurry to be filled is calculated by multiplying the measured slurry concentration by the integrated value of the slurry flow rate. can do. In addition, the slurry filling amount can be calculated by calculating the slurry filling amount per unit time by multiplying the measured slurry concentration, the slurry flow rate (liquid feeding speed), and the unit time, for example, and integrating them. The slurry filling amount can also be calculated by, for example, the product of the slurry concentration, the flow velocity of the slurry, the cross-sectional area of the pipe, and the liquid feeding time.

Further, when the slurry concentration is measured multiple times after the slurry supply to the filter press 11 is started and before the supply is completed, the slurry concentration is newly measured according to the timing of measurement and the timing of calculation. value and used to calculate the slurry fill amount. Also, the average value of the measured slurry concentrations can be used for calculation.

As described above, when a flow meter is provided in the supply pipe 12 or the like to measure the integrated value of the slurry flow rate or the slurry flow rate per unit time, the slurry The flow rate can also be updated with a newly measured value and used to calculate the slurry charge.

The filtration method of the present embodiment can have any process other than the slurry filling amount calculation process. For example, a target value for the slurry filling amount to the filter press is determined in advance, and when the slurry filling amount calculated in the slurry filling amount calculation step reaches the target value, the supply of the slurry to the filter press 11 is stopped. , slurry supply stop step. For example, in the case of the filtration device 10 shown in FIG. 1, the slurry supply stop step can be performed by closing the valve 15 provided in the supply pipe 12 by the control/calculation means 16 .

In addition, the filtration method of the present embodiment includes a filtration step of filtering (pressure filtration) the slurry supplied to the filter press 11 by the filter press 11 after the slurry supply stop step, and a cake obtained by the filtration step. It is also possible to have a washing step or the like in which washing water is supplied to and re-squeezed to wash.

In addition, in the filtration method of the present embodiment, solids in the filtrate are measured by the filtrate concentration measuring means 18 for measuring the concentration of solid components in the filtrate, which are arranged in the pipe 17 for discharging the filtrate from the filter press. There may also be a correction step of measuring the concentration of components and correcting the slurry charge based on the concentration of solid components in the filtrate.

The filtrate concentration measuring means 18 is not particularly limited, but as described above, it may be a fluorescent X-ray device, a transmission X-ray measuring device, a slurry concentration measuring device using a differential pressure method, a turbidity meter, or an ultrasonic measurement. It is preferable to use one or more selected from devices and the like. In particular, the filtrate concentration measuring means is more preferably one or more selected from turbidimeters and ultrasonic measuring devices.

In the correction step, the number and timing of measuring the concentration of the solid component in the filtrate by the filtrate concentration measuring means 18 are not particularly limited, and the measurement can be performed at any timing and any number of times. However, in order to more accurately grasp the concentration of solid components in the filtrate and particularly accurately correct and calculate the amount of slurry to be charged, it is preferable to carry out this process twice or more after starting the supply of the slurry to the filter press 11, for example. .

The specific procedure for correcting the amount of slurry charged into the filter press 11 based on the measured concentration of solid components in the filtrate is not particularly limited. The amount of solid components flowing out from the filtrate can be calculated by multiplying this with the integrated value of the amount of liquid that has passed through. Then, correction can be performed by subtracting the amount of the solid component that has flowed out from the calculated filtrate from the slurry filling amount.

In addition, the amount of the solid component discharged by the filtrate is determined by the product of the measured concentration of the solid component in the filtrate, the flow rate of the filtrate (flow rate), and the unit time. It can also be calculated by calculating the amount of the outflowing solid component and accumulating it. The amount of solid components discharged by the filtrate can also be calculated, for example, by multiplying the concentration of the solid components in the filtrate, the flow rate of the filtrate, the cross-sectional area of the discharge pipe, and the liquid feeding time.

Further, when measuring the concentration of the solid component in the filtrate multiple times after starting the supply of the slurry to the filter press 11, the concentration of the solid component in the filtrate may vary depending on the timing of measurement and the timing of calculation. The concentration can be updated with a newly measured value and used to calculate the amount of solid components washed out by the filtrate. In addition, the average value of the measured concentration of the solid components in the filtrate can also be used for the calculation.

When a flow meter is provided in the discharge pipe 17 or the like and the integrated value of the flow rate of the filtrate or the flow rate of the filtrate per unit time is also measured, the flow rate of the filtrate may be changed according to the timing of measurement or the timing of calculation. It is also possible to update the liquid flow rate to a newly measured value and use it to calculate the amount of solid components washed out by the filtrate.

According to the filtration method of this embodiment described above, it is possible to more accurately calculate and control the amount of slurry charged into the filter press. Therefore, it is possible to suppress variations in the components remaining in the cake obtained after solid-liquid separation and washing.

Although specific examples and comparative examples will be given below, the present invention is not limited to these examples.
[Example 1]
Slurry was filtered in the following procedure using a device having the same configuration as the filtering device 10 shown in FIG. .

As the filter press 11, a concave plate type pressure filter was used, and as the slurry concentration measuring means 14, an integrating sphere type turbidity meter (Model: PT-200 manufactured by Mitsubishi Chemical Analytech Co., Ltd.) was used. Incidentally, the correlation between the slurry concentration and the turbidity detected by the turbidity meter was measured in advance to create a calibration curve.

Further, as the slurry supply means 13, an alkaline slurry containing a composite hydroxide containing Ni, Co, and Al as a solid component, which is a positive electrode active material precursor for a lithium ion secondary battery, is put in a slurry undiluted solution tank. was used. The slurry concentration was adjusted to 100 g/L.

Then, the slurry was supplied from the slurry supply means 13 to the filter press 11 through the supply pipe 12 .

At this time, the slurry concentration of the slurry supplied to the filter press 11 was measured by the slurry concentration measuring means 14 every 5 minutes. Based on the measured slurry concentration, the amount of slurry to be filled into the filter press was calculated by the control/calculation means 16 as follows. (Slurry filling amount calculation step)
After measuring the slurry concentration and before measuring the next slurry concentration, the measured slurry concentration is used to calculate the slurry concentration × unit time (5 minutes) × slurry flow rate to the filter press per unit time. A filling amount (hereinafter referred to as "unit slurry filling amount") was calculated. After newly measuring the slurry concentration, the slurry concentration in the above formula was updated to the latest slurry concentration, and the unit slurry filling amount was calculated in the same manner. Then, by integrating the calculated unit slurry filling amounts, the slurry filling amount to the filter press after starting the supply of the slurry was calculated.

Also, the slurry flow rate was measured by a flow meter (not shown) installed in the supply pipe 12 at the same timing as the slurry concentration was measured, and updated.

When the slurry filling amount reached a predetermined target value, the valve 15 was closed by a command from the control/calculation means 16 to stop the slurry supply to the filter press 11 (slurry supply stop step).

Next, the slurry supplied to the filter press 11 was filtered (solid-liquid separation) by the filter press 11 (filtration step).

The cake obtained after the filtration step was analyzed with a fluorescent X-ray device to measure the chlorine content.

When the slurry was similarly filtered 10 times, the variation in chlorine content in the resulting cake was 5%.
[Example 2]
Filter in the same manner as in Example 1 except that an ultrasonic attenuation type turbidity meter (manufactured by Ultrasonic Industry, model: UAM-4 MKII), which is a type of ultrasonic measurement device, was used as the slurry concentration measurement means. A slurry of a positive electrode active material precursor for a lithium ion secondary battery was supplied to a press, filtered, and variations in chlorine content in the cake were evaluated.

When the slurry was filtered 10 times in the same manner as in Example 1, the variation in chlorine content in the resulting cake was 5%.
[Example 3]
The filtrate concentration measuring means 18 and the filtration device 10 having a flow meter (not shown) for measuring the flow rate of the filtrate are arranged in the filtrate discharge pipe 17, and the filtrate measured by the filtrate concentration measuring means 18 Slurry was filtered in the same manner as in Example 1, except that a correction step was performed to correct the amount of slurry charged based on the concentration of solid components therein.

As the filtrate concentration measuring means 18, an integrating sphere type turbidity meter (model: PT-200, manufactured by Mitsubishi Chemical Analytech Co., Ltd.), which is the same as the slurry concentration measuring means 14, was used. Then, the correlation between the concentration of the solid components in the filtrate and the turbidity detected by the turbidity meter was measured in advance to create a calibration curve.

In addition, the filtrate concentration measuring means 18 and the flow meter installed in the discharge pipe 17 can transmit the concentration of the solid component in the filtrate calculated from the turbidity data of the filtrate to the control/calculating means 16. , it is connected to the control/calculation means 16 .

The filtrate concentration measuring means 18 and the flow meter for measuring the flow rate of the filtrate measured the concentration of solid components in the filtrate discharged from the filter press 11 and the flow rate, respectively, every 5 minutes. Then, the control/calculation means 16 corrected the amount of slurry charged into the filter press as follows, based on the measured concentration of solid components in the filtrate and the flow rate of the filtrate.
(Correction process)
After measuring the concentration of the solid components in the filtrate and the flow rate of the filtrate, and before measuring the concentration of the solid components in the filtrate and the flow rate of the filtrate, Using the concentration and flow rate, the concentration of the solid component in the filtrate × unit time (5 minutes) × the flow rate of the filtrate, the amount of solid component flowing out from the filter press by the filtrate per unit time (hereinafter referred to as "unit ) was calculated. After newly measuring the concentration and flow rate of the solid components in the filtrate, update the concentration and flow rate of the solid components in the filtrate in the above formula to the latest concentration and flow rate of the solid components in the filtrate. , the unit outflow solid component amount was calculated in the same manner. Then, the calculated unit outflow solid component amount was integrated and subtracted from the slurry filling amount calculated in the slurry filling amount calculation step, thereby correcting the slurry filling amount.

In the above-described slurry supply stop step, when the corrected slurry filling amount reaches a predetermined target value, the valve 15 is closed by a command from the control/calculation means 16, and the slurry is supplied to the filter press 11. supply has been discontinued.

As described above, the slurry of the positive electrode active material precursor for lithium ion secondary batteries was supplied to the filter press, filtered, and the variations in chlorine content in the cake were evaluated.

When the slurry was filtered ten times in the same manner as in Example 1, the variations in the chlorine content in the resulting cake were less than 5%.
[Example 4]
As the slurry concentration measuring means 14 and the filtrate concentration measuring means 18, an ultrasonic attenuation type turbidity meter (manufactured by Ultrasonic Industry, model: UAM-4 MKII), which is a kind of ultrasonic measuring device, was used. In the same manner as in Example 3, the slurry of the positive electrode active material precursor for lithium ion secondary batteries was supplied to the filter press, filtered, and the variations in chlorine content in the cake were evaluated.

When the slurry was filtered ten times in the same manner as in Example 1, the variations in the chlorine content in the resulting cake were less than 5%.
[Comparative Example 1]
Slurry was filtered using a filtration device having the same structure as in Example 1 except that it did not have slurry concentration measuring means 14 .

After the supply of slurry from the slurry supply means 13 to the filter press 11 through the supply pipe 12 is started, when calculating the slurry filling amount in the slurry filling amount calculation step, the slurry concentration is the slurry when the slurry is prepared. A concentration of 100 g/L was used. Except for the above points, the slurry supply to the filter press 11, suspension of the slurry supply, and filtration (filtration step) were carried out under the same conditions as in Example 1.

Then, the cake obtained after the filtration step was analyzed by fluorescent X-rays to measure the content of chlorine.

When the slurry was similarly filtered 10 times, the variation in chlorine content in the resulting cake was 20%.

When compared with the results of Examples 1 to 4, it was confirmed that Comparative Example 1 had greater variations in chlorine content in the resulting cake. This is probably because the amount of slurry charged into the filter press could not be accurately evaluated, resulting in variations in the amount of slurry charged.

10 Filtration Device 11 Filter Press 12 Supply Pipe 14 Slurry Concentration Measuring Means 17 Discharge Pipe 18 Filtrate Concentration Measuring Means

Claims (4)

filter press and
Slurry concentration measuring means for measuring the concentration of solid components in the slurry, arranged in a slurry supply pipe to the filter press;
Filtrate concentration measuring means for measuring the concentration of solid components in the filtrate, arranged in a pipe for discharging the filtrate from the filter press;
Based on the concentration of the solid component in the slurry measured by the slurry concentration measuring means, the slurry filling amount, which is the amount of the solid component in the slurry filled in the filter press, is calculated, and the filtrate concentration measuring means and a control/calculation means for correcting the slurry filling amount based on the measured concentration of the solid component in the filtrate. 2. The filtration device according to claim 1, wherein said slurry concentration measuring means is one or more selected from a turbidity meter and an ultrasonic measuring device. A filtration method for supplying slurry to a filter press and filtering the slurry with the filter press,
Measure the slurry concentration, which is the concentration of solid components in the slurry supplied to the filter press, by a slurry concentration measuring means arranged in the supply pipe of the slurry to the filter press,
A slurry filling amount calculation step of calculating a slurry filling amount, which is the amount of solid components in the slurry filled in the filter press, based on the slurry concentration ;
measuring the concentration of the solid component in the filtrate by a filtrate concentration measuring means for measuring the concentration of the solid component in the filtrate, which is arranged in the pipe for discharging the filtrate from the filter press;
and a correction step of correcting the slurry filling amount based on the concentration of solid components in the filtrate. 4. The filtration method according to claim 3 , wherein said slurry concentration measuring means is one or more selected from a turbidity meter and an ultrasonic measuring device.

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