JP7070096B2 - How to operate the filter press - Google Patents

Description

The present invention relates to an operation method of a filter press. More specifically, the present invention relates to a method of operating a filter press for washing and dehydrating various slurries in all industrial fields.

The filter press has been conventionally used in the step of washing and dehydrating various slurries. Further, as described in Patent Document 1, a filter plate provided with a filter plate having grooves formed as flow paths of the filtrate on both sides and a diaphragm having grooves formed as flow paths of the filtrate on both sides. A filter press having a structure in which the above are alternately arranged and has a function of expanding the diaphragm to squeeze the starch in the filter chamber is widely used. The conventional general operation method of this filter press was as follows.
A filtration step is performed in which the slurry is supplied into the filter chamber and filtered, and then a squeezing step is performed in order to squeeze out the water content of the filtered starch. After that, if necessary, the washing step and the squeezing step are executed in that order.

A typical process including the above-mentioned conventional general operation method is shown as an example in FIG.
In this example, a closed frame S101 of a plurality of dehydration units, a filtration step S102 of supplying slurry to the filter chamber of each dehydration unit to separate solid and liquid, and a pressing step S103 of pressing the starch in the filter chamber to squeeze water. , Washing step S104 for washing the starch with washing water, re-squeezing 2 step S105, center blow step S106 for discharging residual slurry and the like in the stock solution supply hole of the dehydration unit, and cake from which water has been removed from the starch. The opening frame S107 for taking out is performed in that order.

However, in the above-mentioned conventional operation method, the adhering liquid cannot be efficiently diluted in the cleaning step S104, and if the required level of dilution is performed, a large amount of cleaning water is required or high-pressure cleaning water is required. There was a problem of doing.
However, doing so has the drawback of increasing the operating costs of the filter press.

Further, for the purpose of effectively washing and dehydrating the starch, the operation method described in Patent Document 2 includes a filtration step of supplying the slurry into a filter chamber and filtering it, a washing step of washing the filtered starch, and washing. The squeezing process of squeezing the starch is carried out in that order.
However, since the cleaning process is performed without dehydrating the residual water in the filter chamber after the filtration process, there is a problem that the substance to be cleaned in the residual water is brought into the cleaning process as it is, and the cleaning effect is deteriorated. ..

Japanese Unexamined Patent Publication No. 2014-176818 Japanese Unexamined Patent Publication No. 2006-68659

In view of the above circumstances, it is an object of the present invention to provide an operation method of a filter press capable of efficiently cleaning starch.

The operation method of the filter press of the first invention is the operation method of the filter press for solid-liquid separation of the slurry, the filtration step of supplying the slurry into the filter chamber and filtering it, and supplying air to the filter chamber. A cake blow step of passing through the filtered starch, a washing step of supplying washing water to the filter chamber to wash the starch, and a squeezing step of squeezing the starch in the filter chamber . It is characterized in that the opening step of opening the filter chamber and dropping the starch as a cake is performed in that order.
In the first aspect of the invention, the method of operating the filter press according to the second invention is such that the cake blowing step supplies air into the filter chamber from the stock solution supply hole of the dehydration unit provided in the filter press and allows the air to pass through the starch. Moreover, it is characterized in that it is a step of allowing air to pass through the filter cloth and passing air toward the filtrate discharge holes formed in the filter plate.
In the second aspect of the invention, the method of operating the filter press according to the third invention is such that in the cleaning step, cleaning water is supplied from the stock solution supply hole into the filter chamber to allow the starch to pass through and the filter cloth to permeate. It is a step of passing washing water toward the filtrate discharge hole formed in the filter plate.
The operation method of the filter press of the fourth invention is the solid-liquid separation of the de-Fe starch in the de-Fe step in which the operation method is the purification step of the electric nickel production process in the first, second or third invention. It is characterized by being used in.

According to the first invention, when air is blown into the filter chamber in the cake blowing step for the starch immediately after filtration and before being squeezed, the air passes through the starch and permeates the filter cloth from the filter chamber. It is exhausted. At this time, the residual water in the filter chamber is discharged together with the air, so that the cleaning efficiency in the cleaning step is improved. Since it is considered that the permeation of the air through the two filter cloths in the filter chamber is performed substantially evenly, the starch is not unevenly present on one filter cloth side in the filter chamber. Therefore, since there is no escape route for the washing water, the washing liquid can wash the starch evenly when the washing process is started, and the washing efficiency is improved.
According to the second invention, when the air supplied from the liquid supply pipe into the filter chamber passes through the starch, an air passage is created in the starch, but after that, the air permeates perpendicularly to the filter cloth and the filter plate is used. It escapes to the filtrate discharge hole of. Since it is estimated that the sediment adheres to the two filter cloths with almost equal thickness due to the passage of air at this time, the cleaning water in the subsequent cleaning step adheres to the two filter cloths. It is believed that it can pass through almost all of the material and be washed. Therefore, the cleaning efficiency is high.
According to the third invention, the washing water passes through the starch which is presumed to be attached to the two filter cloths at almost equal thickness, and flows and permeates perpendicularly to the filter cloths. It is believed that almost all of the sediment can be washed. Therefore, the cleaning efficiency is high, and a large amount of the adhering liquid adhering to the starch can be washed away, so that the dilution rate of the adhering liquid is also high.
According to the fourth invention, when the operation method of the present invention is used for solid-liquid separation of the de-Fe starch slurry in the de-Fe step, the de-Fe starch slurry is divided into a solid cake and a filtrate. Then, the starch before it becomes a cake is washed in the washing step, but at that time, since a large amount of the water-soluble valuable metal in the adhering liquid can be discharged, the water-soluble valuable metal remaining in the starch and discarded. The amount can be reduced and the loss of valuable metal can be reduced.

It is a process drawing which shows the operation method of the filter press which concerns on this invention. It is a basic block diagram of the filter press used in this invention. It is an exploded view which shows the basic structure of a dehydration unit. It is explanatory drawing of important steps S2 to S5 in the operation method of this invention. It is a partially enlarged view of the dehydration unit in the cake blowing step S3 and the washing step S4 shown in FIG. It is a process drawing which shows the operation method of the conventional filter press. It is explanatory drawing of the problem of the conventional operation method.

Next, an embodiment of the present invention will be described with reference to the drawings.
First, the basic structure of the filter press to which the operation method of the present invention is applied will be described.
The filter press A shown in FIGS. 2 to 4 is an example among various forms, and the filter press to which the present invention is applicable is not limited to this.

The filter press A shown in FIG. 2 has a configuration in which a large number of dehydration units 4 are arranged in parallel between two pairs of holding frames 1 and 2. The stock solution supply pipe 11, the filtrate discharge pipe 12 for discharging the filtrate, and the squeezed fluid supply pipe 13 for sending the squeezed fluid are connected to one holding frame 1 (fixed side). A hydraulic cylinder 3 is attached to the other holding frame 2 (movable side) so that the holding frame 2 can be brought close to and separated from the holding frame 1. When the dehydration units 4 are tightened by the hydraulic cylinder 3 or the like, the frames are closed in close contact with each other, and when the hydraulic cylinders 3 or the like are loosened, the frames are separated from each other and opened.

As shown in FIG. 3, each dehydration unit 4 is configured by alternately arranging a normal filter plate 4a and a pressing filter plate 4b. In FIG. 3, two filter plates 4a and 4b are shown in a closed frame state, and one filter plate 4a is shown in a state of being further expanded than in a normal open frame state. Each of the filter plates 4a and 4b is a substantially quadrangular plate member, the outer edge portion is thick, and the inside of the outer edge portion is formed in a concave portion. A stock solution supply hole 5 is formed in the center of each of the filter plates 4a and 4b, a filtrate discharge hole (not shown) is formed in three of the four corners of the outer edge portion, and a squeeze (not shown) is formed in one of the four corners. A fluid supply hole is formed.

When the filter plates 4a and 4b are fastened to each other and closed, the undiluted solution supply hole 5, the filtrate discharge hole (not shown), and the squeezed fluid supply hole communicate with each other like a single communication pipe. The space where the two recesses of the filter plates 4a and 4b face each other becomes the filter chamber 6.

Two filter cloths 7 are arranged in each filter chamber 6. When the slurry is supplied between the two filter cloths 7 and 7, water is permeated through the filter cloth 7 and the solid content of the slurry is left as a starch r to separate the solid and liquid.

The squeezed filter plate 4b is covered with a rubber diaphragm 8, and when the diaphragm 8 is inflated with a squeezing fluid such as pneumatic pressure, the starch left in the filter chamber 6 is removed through the two filter cloths 7. Squeezing can be performed to perform further solid-liquid separation by compression.

A large number of grooves 9 are formed on the surface of the filter plate 4a facing the filter chamber 6, and a large number of grooves 9 are also formed on the surface of the diaphragm 8 (the side facing the filter cloth 7).
Moisture squeezed in the filtration step or the squeezing step permeates the filter cloth 7, passes through the groove 9 formed in the filter plate 4a or the diaphragm 8, and discharges the filtrate formed in the corners of the filter plates 4a and 4b. Guided to the hole.
The starch after being squeezed is compacted and integrated, and is also called cake k. This cake k is discharged downward when the frame is opened.

The filter plates 4a and 4b shown in FIG. 3 are examples of various types of dehydration units 4, and are formed in a stock solution supply hole 5, a filtrate discharge hole, a squeezed fluid supply hole, and the like, and a groove 9 for discharging water. There are various patterns and the like, and any of them can be arbitrarily adopted.
As the squeezing fluid for expanding the diaphragm 8, a liquid may be used, or a gas such as air may be used.

Here, the present inventors have elucidated the cause of the problems of the prior art that are the background of the technical principle of the present invention, and the present invention will be described.
As described above, in the conventional operation method, the adhering liquid cannot be efficiently diluted in the cleaning step S104, and if the required level of dilution is performed, a large amount of cleaning water is required or high-pressure cleaning water is required. There was a problem of
FIG. 7 shows each state of the dehydration unit in the three steps including the filtration step S102, the squeezing step S103, and the washing step S104 in the prior art. In the figure, 4a is a normal filter plate and 4b is a squeeze filter plate, showing some of a large number of dehydration units. In the figure, gaps can be seen between the filter plates 4a and 4b and between the two filter cloths 7 and 7, but this is because the figure is easy to understand. The outer edges of the filter cloth are also in close contact with each other.

In the filtration step S102, the slurry sl is supplied between the two filter cloths 7 and 7, and the water is removed through the filter cloth 7 to separate the solid and liquid. What is left as a solid component becomes a starch r. In the next pressing step 1 S103, the diaphragm 8 expands to squeeze the starch r between the two filter cloths 7 and 7, and further solid-liquid separation is promoted. In the filter chamber 6 after the pressing step 1 S103 is executed, the starch r pressed by the diaphragm 8 is unevenly distributed on one filter cloth 7 side, and when the diaphragm 8 after pressing returns to the original position. It is presumed that a space g will be formed between the other filter cloth 7 and the starch r.

Then, when the washing step S104 of the next step is entered and the washing water w is supplied to wash the starch r, most of the washing water w does not have the starch r attached because the space g is formed in the previous step. It will come off to the filter cloth 7 side, which has less passage resistance. In this case, most of the washing water goes out of the filter chamber 6 through the filter cloth 7 without diluting the adhering liquid of the starch r, and the washing efficiency is lowered as described above. The elucidation of this phenomenon is linked to the technical principle of the present invention (so-called uniform thickness distribution action) described later.
Therefore, if sufficient cleaning is to be performed in this conventional technique, measures such as increasing the pressure of the cleaning water to forcibly pass through a starch having a large passage resistance or increasing the amount of the cleaning water used are taken. Was needed.

Next, the operation method of the present invention will be described with reference to FIG.
The operation method of the present invention comprises each of the closing frame S1, the filtering step S2, the cake blowing step S3, the cleaning step S4, the squeezing step S5, the center blow step S6, and the opening frame S7, and the operation method is executed in that order.
In addition to the above steps, known steps such as depressurization and drainage are also included in the actual operation, but the description thereof is omitted in the present specification.

Hereinafter, the details of the above steps will be described with reference to FIGS. 4 and 5.
FIG. 4 shows the state of the dehydration unit 4 in the filtering step S2, the cake blowing step S3, the washing step S4, and the squeezing step S5 among the above steps. Further, FIG. 5 shows an enlarged part of the dehydration unit 4 in the cake blowing step S3 and the washing step S4.
In FIGS. 4 and 5, the filter plates 4a and 4b and the two filter cloths 7 and 7 are shown with a slight gap, but this is to make the shape easy to understand and in the actual process. The outer edge portions of the filter plates 4a and 4b are in a closed frame state in close contact with each other, and the two filter cloths 7 are also pressed by the outer edge portions of the filter plates 4a and 4b and closed to each other to form a bag shape.

S1: Closed frame The closed frame S1 shown in FIG. 1 is performed by tightening a plurality of (usually 50 to 60) dehydration units 4 between the holding frames 1 and 2 shown in FIG. 2 with a hydraulic cylinder 3. As a result, there is no gap between the outer edges of the filter plates 4a and 4b shown in FIG. 4, and the stock solution supply hole 5, the filtrate discharge hole and the squeezed fluid supply hole are also communicated with each other so that the filtration step and the squeezing step can be executed. Become.

S2: Filtration In the filtration step S2 shown in FIG. 1, the slurry sl supplied in the stock solution supply pipe 11 (see FIG. 2) is filtered through the stock solution supply holes 5 of the filter plates 4a and 4b as shown in FIG. This is done by supplying between the two filter cloths 7 and 7 in the chamber 6. The slurry sl is filled between the filter cloths 7 and 7 and then filtered and solid-liquid separated. The separated solid content becomes starch r. Further, the separated filtrate is collected in the filtrate discharge hole through the grooves 9 formed in each filter plate 4a and the diaphragm 8, and is discharged to the outside from the filtrate discharge pipe 12 (shown in FIG. 2).

S3: Cake blow step In the cake blow step S3 shown in FIG. 1, air a is supplied from the stock solution supply pipe 11 (FIG. 2), and as shown in FIGS. 4 and 5, the stock solution supply hole 5 is used in the filter chamber 6. This is performed by sending air a into the starch r of the above.
This air a permeates perpendicularly to the filter cloth 7 from various parts of the filter cloth 7 while passing through the starch r, and then forms a groove 9 formed in the filter plate 4a and the diaphragm 8 on the outside of the filter cloth 7. It flows along and is collected in three filtrate drain holes.

The air a passing through the starch r in this way passes through the starch r, and at this time, the starch r is pressed against the two filter cloths 7 and 7. Therefore, it is presumed that the starch r is pressed against the two filter cloths 7 and 7 with almost equal thickness, and the starch r as generated in the prior art exists on one filter cloth 7 side. There is no uneven distribution. Therefore, it is considered that the resistance to the passage of the air a becomes uniform as a whole with respect to the two filter cloths 7 and 7.
Here, the term "overall" means that even if there is a large amount of air a that escapes to one filter cloth 7 due to local fluctuations in the thickness of the starch r, there is also air a that escapes to the other filter cloth 7 in another place. Since it exists, it means that the amount of air a passing between the two filter cloths 7 and 7 is almost the same.

Further, as a result of the air a passing through the starch r as described above, it is presumed that a gap space h serving as a passage for the air a is formed, but the gap space h approaches one filter cloth 7 or the other. Although it is close to the filter cloth 7 of the above, it is considered that it has an equal distance from the two filter cloths 7 and 7 as a whole. It should be noted that this path also serves as a path for washing water in a later process.

As described above, in the cake blow step S3, water is squeezed out from the starch r by applying air pressure, and the starch r is brought into close contact with the filter cloth 7 to make the thickness of the starch uniform for the two filter cloths 7 and 7. It is thought that it has the effect of making it.
As described above, it is considered that the cake blowing step S3 of the present invention exerts a dehydration action and a uniform thickness distribution action of starch, but the latter uniform distribution of starch thickness is important.
That is, since the passage resistance of both the left and right sides (two filter cloths 7 and 7) in the filter chamber 6 becomes uniform due to this uniform thickness distribution action of the starch, a uniform amount of wash water is used in the subsequent wash step S4. There is a flow.
Further, when the thickness of the starch is the same in this way, it is possible to generate a precondition that a uniform flow rate can be flowed even with low-pressure washing water.

S4: Cleaning step In the cleaning step S4 shown in FIG. 1, cleaning water is supplied from the stock solution supply pipe 11 (FIG. 2), and as shown in FIGS. 4 and 5, two filter cloths 7 are supplied from the stock solution supply holes 5. This is performed by supplying the washing water w into the starch r sandwiched between the two. The supplied washing water w fills the gap space h presumed to have been created in the cake blowing step S3, and the washing water w passes through the starch r and passes through perpendicularly to the filter cloth 7 and permeates. Then, it is collected in the filtrate discharge hole through the groove 9 of each filter plate 4a and the groove 9 of the diaphragm 8, and finally is discharged to the outside from the filtrate discharge pipe 12 (see FIG. 2).
At this time, the water-soluble valuable metal and the like adhering to the starch r are washed away.

In the above-mentioned washing step S4, it is presumed that the starch r in the filter chamber 6 is not unevenly distributed on one side and exists in the two filter cloths 7 and 7 in a substantially uniform thickness, so that the washing water is washed. The passage resistance of w is also made uniform with respect to the two filter cloths 7 and 7 (filter surfaces on both the left and right sides), and as a result, the washing water w can be passed through almost the entire amount of the starch r.

The main point of the action of the present invention is not to crush the starch in the filter chamber, but to allow the washing water to pass evenly through the starch. Therefore, the washing water used in this step may be low-pressure water, and even if the amount used is small, the starch can be sufficiently washed. Low-pressure water refers to washing water having a pressure equal to or lower than the supply pressure of the slurry sl. Therefore, in general, the supply pressure of the slurry sl is about 0.2 to 0.3 MPa, but the pressure of the washing water may be about 0.1 MPa. Therefore, utility water for cleaning, cooling, etc. in a general plant can be used as it is without increasing the pressure.

S5: Squeezing step The squeezing step S5 shown in FIG. 1 is performed by expanding the diaphragm 8 as shown in FIG.
The squeezing fluid that expands the diaphragm 8 is supplied from the squeezing fluid supply pipe 13 (see FIG. 2), passes through the squeezing fluid supply holes formed in the filter plates 4a and 4b, and the diaphragm from the through hole in the squeezing filter plate 4b. It is supplied to the back surface of 8.
As shown in FIG. 4, in this squeezing step S5, the gap between the two filter cloths 7 and 7 is pushed by the diaphragm 8 to narrow the gap, and the solid-liquid separation of the starch r is further promoted to reduce the water content. The resulting starch r is obtained.

S6: Center blow process
Residual slurry, etc. in the stock solution supply hole is discharged.
S 7 : Open frame
When the supply of the pressing fluid is stopped and the diaphragm 8 is contracted, the pressing force acting on the starch r sandwiched between the filter cloths 7 is released. Then, when the hydraulic cylinder 3 is contracted to open each dehydration unit 4, the space between the filter plates 4a and 4b opens as shown in FIG. 3, so that the starch can be dropped as a cake k and taken out to the outside. can.

According to the operation method of the present embodiment, when the air a is blown into the filter chamber 6 in the cake blowing step S3, the air a passes through the starch r, passes through the filter cloth 7, and is exhausted from the filter chamber 6. .. Since it is considered that the permeation of the air a into the two filter cloths 7 and 7 in the filter chamber 6 is performed almost evenly, the adhering liquid is squeezed out from the starch r and the sediment r is squeezed out from the sediment r. It is presumed that it will not be biased toward the filter cloth 7 side. Therefore, compared to the conventional method of squeezing out water from the starch r, there is no escape route for the washing water w. Therefore, when the washing step S4 is started, the washing water w can wash the starch r evenly, and the washing efficiency is improved. It gets higher.

As one of the application examples of the operation method of the present invention, a liquid purification process in an electric nickel manufacturing process will be described.
In the electric nickel production process, a metal component in a raw material including Ni is leached in a chlorine leaching step to generate a crude Ni chloride solution. Since this crude Ni chloride solution contains metal components such as Fe ions as impurities, electric Ni is produced by electrowinning after removing these impurities in the purification step.
This purification step also includes a de-Fe step, in which a de-Fe starch is produced by neutralizing the crude Ni chloride solution under oxidizing conditions, and the de-Fe starch slurry is filtered to remove Fe as a solid. ing. The removed Fe-free starch is discharged outside the factory. Therefore, Ni distributed to the de-Fe starch becomes a loss.

However, when the operation method of the present invention is applied to the slurry treatment of the de-Fe step, as described above, the washing step S4 of the present invention has the effect of dehydrating the starch and the effect of uniformly distributing the thickness of the starch by the prior cake blowing step S3. As a result of the permeation of the washing water into the filter cloth evenly between the two filter cloths, it is considered that almost the entire amount of the starch can be washed. As a result, the water-soluble Ni adhering to the starch can be recovered together with the washing water, so that the amount of Ni distributed to the starch discharged out of the factory is reduced.

According to the above embodiment, the amount of water-soluble Ni remaining in the cake was reduced to 44% of the conventional amount even if the amount of washing water was the same.

The operation method of the present invention can be applied to any step as long as it is a step of solid-liquid separation of the slurry without particular limitation. For example, it can be used for solid-liquid separation of slurry generated in manufacturing processes such as chemical industry, food industry, mining industry, pharmaceutical industry, paper and pulp industry, electric and electronic industry, and wastewater treatment process.

A Filter press S1 Closed frame S2 Filtration process S3 Cake blow process S4 Cleaning process S5 Squeezing process S6 Center blow process S7 Opening frame 1, 2 Holding frame 3 Hydraulic cylinder 4 Dehydration unit 4a Normal filter plate 4b Squeezing filter plate 5 Undiluted solution supply hole 6 Filter chamber 7 Filter cloth 8 Diaphragm 9 Groove 11 Stock solution supply pipe 12 Filtration discharge pipe 13 Squeezed fluid supply pipe

Claims (4)

It is a method of operating a filter press for solid-liquid separation of slurry.
The filtration step of supplying the slurry into the filtration chamber and filtering the slurry,
A cake blow process in which air is supplied to the filter chamber and passed through the filtered starch.
A washing step of supplying washing water into the filter chamber to wash the starch, and
A squeezing step of squeezing the starch in the filter chamber and
With the opening step of opening the filter chamber and dropping the starch as a cake.
A method of operating a filter press, which comprises executing in that order. In the cake blowing step, air is supplied into the filter chamber from the stock solution supply hole of the dehydration unit provided in the filter press, and the filtrate is passed through the starch and permeated through the filter cloth to be formed on the filter plate. The method for operating a filter press according to claim 1, wherein the step is to pass air toward the discharge hole. In the washing step, washing water is supplied from the stock solution supply hole into the filter chamber to allow the starch to pass through and the filter cloth to permeate, and the washing water is directed toward the filtrate discharge hole formed in the filter plate. The operation method of the filter press according to claim 2 , wherein the process is a passing step. The operation method of the filter press according to claim 1, 2 or 3, wherein the operation method is used for solid-liquid separation of the de-Fe starch in the de-Fe step, which is a liquid purification step of the electric nickel production process. ..

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