JPH11137980A - Cleaning method of slurry - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for cleaning slurry having high permeation flux, prevented in the fouling on the surface of a membrane, capable of treating a high concentration slurry and cleaning the slurry at a high efficiency. SOLUTION: The slurry in a pressurized state is separated into a permeated liquid and a concentrated liquid while vibrating a permeable membrane by giving reciprocating motion of fine amplitude to the permeable membrane in a filter bag 11 in the circumferential direction in a horizontal surface by a torsion bar 12, the permeated liquid is stored in a storage tank 13, the concentrated liquid is returned to a supply tank 9, the same quantity of a cleaning liquid as that of the permeated liquid to be taken-out is replenished to the supply tank 9 and the slurry in the tank 9 is permeation-treated with the permeable membrane in the filter bag 11 until the previously fixed cleaning degree is attained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a latex recovery,
Concentration of colloidal silica, recovery of valuable resources, recovery of valuable resources from waste liquid, metal classification, cell washing, slurry washing method suitable for colloid suspension recovery, etc., more specifically, calcium carbonate, calcium phosphate, titanium oxide or The present invention relates to a slurry washing method capable of washing ions or ultrafine particles adhering to particles in a slurry such as a metal ion-containing solution or a polymer solution to a predetermined washing degree by a diafiltration method.

[0002]

2. Description of the Related Art Conventionally, in the fields of the chemical industry, the paper industry, the pharmaceutical and food industries, etc., for example, membranes for cleaning liquids to be treated such as latex and bacterial cell liquid with a permeable membrane. Separation methods have been employed. As this membrane separation method, a diafiltration method in which a permeable component and a non-permeable component are separated by a permeable membrane having micropores is widely used. In the diafiltration method, as shown in FIG. 1, a slurry in a tank 1 is supplied to a membrane separation device 3 by a pump 2, and the slurry is dispersed by a permeable membrane in the device 3, for example, when the dispersion medium is water. , The permeate (water + low molecular weight solute) and the concentrate (water + high molecular weight solute) are separated, and the concentrate is returned to the tank 1 via the pipe 4
In this method, the permeated liquid is taken out from the pipe 5, the same amount of washing water as the permeated liquid taken out is supplied to the tank 1 through the pipe 6, and the slurry is washed until a predetermined cleaning degree is reached.

However, when the slurry is washed using a conventional cross-flow type membrane separation device such as a hollow, spiral, or tubular type, as shown in FIG. Since the membrane hole 8 is closed by clogging (fouling), the permeation resistance increases, and the permeation flux may decrease. Further, in the conventional cross-flow type membrane separation apparatus, when the viscosity (slurry concentration) of the treatment liquid increases, the shearing force on the membrane surface decreases, so that fouling is likely to occur. Furthermore, in a conventional cross-flow type membrane separation apparatus, in order to generate a shearing force in the fluid near the membrane surface, it is necessary to flow at a high flow rate in the pipe, but the pressure loss of the screen and the bent pipe and various pipe resistances are required. Thus, the efficiency with which the energy input for transporting the fluid is converted into a shearing force for preventing fouling is as small as about 10%.

The present invention has been made in view of the above-mentioned problems of the prior art, and has as its object to provide a high permeation flux, to prevent fouling on the membrane surface, and to form a highly concentrated slurry. It is an object of the present invention to provide a slurry cleaning method capable of performing treatment and cleaning the slurry with high efficiency.

[0005]

In order to achieve the above-mentioned object, the present invention provides a method in which a slurry in a supply tank is pressure-fed to one side of a permeable membrane, and the permeable membrane is vibrated. High concentration components near the membrane surface flow out of the concentration side outlet without contacting the membrane surface due to the shearing force
If a proper pressure is applied to the slurry by a pump, a high permeation flux can be obtained. Further, since a high shear field is formed on the film surface due to the vibration, the film surface is kept clean and fouling is prevented. Furthermore, even if a highly viscous slurry flows, a shear field is generated on the membrane surface due to vibration, so that the water trapped between the particles becomes free water and the fluidity is improved. Since the viscosity coefficient decreases, processing of a highly concentrated slurry becomes possible. Most of the energy for moving the film surface is converted into a fluid near the film surface as a shear force, and the slurry can be washed with high efficiency.

[0006] Thus, the slurry supplied to one side of the permeable membrane is taken out from the other side as a permeate and taken out from one side as a concentrate. The concentrated liquid is returned to the supply tank, the cleaning liquid is supplied to the supply tank, and the above-described processing is repeatedly performed on the slurry in the supply tank, whereby the slurry to be processed can be cleaned to a predetermined cleaning degree.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The gist of the present invention is to supply a pressurized slurry to be processed to one side of a pressure vessel partitioned by a permeable membrane, and to vibrate the permeable membrane to remove the permeable component. Permeate to the other side, take out the concentrate from one side, return this concentrate to the supply tank, take out the permeate from the other side, store this permeate in the storage tank, replenish the washing liquid to the supply tank, A slurry in the supply tank is pressure-fed to the pressure vessel to perform the permeation process, and the process is continuously repeated until the slurry in the supply tank reaches a predetermined cleaning degree. It is in.

According to the present invention having the above-described structure, a high permeation flux can be obtained while preventing fouling on the membrane surface by the shear force generated by the vibration of the permeable membrane. The slurry supplied to one side of the membrane is separated into a permeate and a concentrate and discharged, and the washing solution is added to the concentrate, and the permeation treatment by the permeable membrane is repeated. It is possible to wash to a given degree of washing.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. As a slurry cleaning device provided with a vibration type membrane separation device, for example, a device having a configuration as shown in FIG. 4 can be used. Referring to FIG. 4, 9 is a slurry supply tank, 10 is a pump for pumping the slurry, 1
1 is a filter pack in which a number of permeable membranes are laminated, 12
Is a torsion bar that gives a small amplitude reciprocating motion in the circumferential direction in the horizontal plane to the permeable membrane in this filter pack.
Reference numeral 3 denotes a permeate storage tank. As shown in FIG. 5, a plurality of nonwoven fabric drain cloths 15 and metal plates 16 laminated between upper and lower permeable membranes 14 are horizontally arranged inside the filter pack 11, and It is provided in multiple stages at predetermined intervals in the direction. In the figure, the upper side of the upper permeable film 14 is one side, and the lower side (drain cross side) is the other side. When the slurry to be treated is supplied to one side, the internal pressure of one side is higher than that of the other side (about 2 to 4).
0 kg / cm ² ), so that the permeated components in the slurry to be treated, that is, particles (permeated components) 17 smaller than the pores of the permeable membrane 14 pass through the pores as shown in FIG. And reach the other side. The concentrated liquid after the permeation component permeates is sent to one side of the permeable membrane 14 at the next stage in FIG. 5, and the permeated component passes through the pores of the permeable membrane. During this permeation processing, as shown in FIG. 4, the permeable membrane in the filter pack 11 continues to reciprocate with a small amplitude in the circumferential direction in the horizontal plane due to the action of the torsion bar 12, so that the permeable membrane is A shear force acts on the interface with the slurry, so that the membrane holes do not cause fouling and the pump 10
By applying a more appropriate pressure to the slurry, a high permeation flux can be obtained.

[0010] The permeation process is sequentially performed in this manner, and the obtained permeate is collected in the storage tank 13 through the pipe 18.
The concentrated liquid in the pipe 19 is returned to the supply tank 9, and the cleaning liquid is supplied to the supply tank 9 from the pipe 20. Thus,
The slurry in the supply tank 9 is efficiently separated into a permeated liquid and a concentrated liquid by a vibrating membrane separation device, and a sufficient amount of washing liquid corresponding to the amount of the permeated liquid to be taken out is supplied to the supply tank 9 from the pipe 20. By supplying the slurry in 9 to the filter pack 11 through the conduit 21 and repeating the permeation process, the slurry can be washed to a predetermined washing degree.

Next, a slurry of calcium carbonate having an initial concentration of 10% by weight was subjected to a diafiltration method as shown in FIG.
Under the condition of washing from 2 to 9, the required processing time was calculated for the case where the conventional cross-flow type membrane separation device was used and the case where the vibration type membrane separation device of the present invention was used. Will be described.

First, the meaning of symbols used in the following calculation will be described.

V ₀ = volume of liquid in tank 1 (L), C ₀ = initial concentration of liquid in tank 1, C = concentration of liquid in tank 1 (=
Concentration of the liquid sent from the tank 1 to the membrane separation device 3), V '
= Amount of liquid sent from tank 1 to membrane separation device 3 (L / h
r), V = amount of permeate taken out from membrane separator 3 (= amount of washing water supplied to tank 1, L / hr), V _C
= Amount (L) of the concentrate returned from the membrane separation device 3 to the tank 1.
/ Hr), C _C = concentration of the concentrated liquid returned from the membrane separation device 3 to the tank 1, C _W = concentration of washing water supplied to the tank 1, and A = membrane area (m ² ). The concentration means the concentration of calcium carbonate, and L indicates liter.

(1) In the case where a conventional cross-flow type membrane separation apparatus is used: The concentration C ₀ of the liquid in the tank 1 is 10%, and the concentration C _{C of the} concentrated liquid is 11%. Therefore, Vc = 10V '/ 11, V = V' / 11,... When determining the material balance in the tank 1, and _{C W V + CV C -CV' =} V 0 · dC / dt ···. By substituting the equation into the equation, C _W V + C · 10/11 · V′−CV ′ = V ₀ · dC / dt. Since C _W (calcium carbonate concentration in water) is negligible compared to C, if C _W V = 0, −1 / 11 · V ′ / V ₀ = 1 / C · dC / dt −1 / 11 · V ′ / V ₀ · dt = 1 / C · dC The left side of the equation is integrated from 0 to t, and the right side is C ₀
From C to C, and t is obtained as follows: −1 / 11 · V ′ / V ₀ • t = Log (C / C ₀ )... T = 11 · V ₀ / V ′ · Log (C ₀ / C). Assuming that the time when the volume V _{0 of the} tank 1 is replaced by the water having the volume V ₀ is T ₁ , T ₁ = V ₀ / V = 11 · V ₀ / V ′. Here, the initial OH ^- concentration of the liquid in the tank 1 is represented by C
_Assuming that _OH0 and the OH ^- concentration of the liquid in the tank 1 are C _OH ,
The equation is: t = 11 · V ₀ / V ′ · Log (C _OH0 / C _OH ). _{Assuming that} the time required for the pH in the tank 1 to change from 12 to 9 (the required processing time) is T ₀ , T ₀ = 11 · V ₀ / V ′ · Log (C _OH0 / C _OH) ) = T ₁ Log (C _OH0 / C _OH ), while C _OH0 = 10 ⁻² (OH ⁻ mol / L),
Since C _OH = 10 ⁻⁵ (OH ⁻ mol / L), the equation is: T ₀ = 3 · T ₁ (10) Therefore, when V ₀ is replaced with water for three times,
Changes from 12 to 9. Here, if the material balance in the membrane separation device 3 is obtained, V ′ = V + V _{C. According} to the experimental data obtained by the inventor, the average permeation flow rate at a concentration of 10% is 40 L.
/ M ² / hr, V _C = 10 V ′ / 11, V = 40 A
Therefore, V ′ = 440A. This value into equation, T ₁ = V ₀ / 40A, and the thus processing time by a conventional cross-flow type membrane separation apparatus T ₀ than (10), and T ₀ = 3V ₀ / 40A.

(2) When the vibrating membrane separation device of the present invention is used Assume that the concentration C ₀ of the liquid in the tank 1 is 10% and the concentration C _{C of the} concentrated liquid is 15%. Therefore, Vc = 2V '/ 3, V = V' / 3,... When determining the material balance in the tank 1, and _{C W V + CV C -CV' =} V 0 · dC / dt ···. By substituting the equation into the equation, C _W V + C · 2/3 · V′−CV ′ = V ₀ · dC / dt. Since C _W (concentration of calcium carbonate in water) is negligible compared to C, if C _W V = 0, then −1 / 3 · V ′ / V ₀ = 1 / C · dC / dt −1 / 3 · V ′ / V ₀ · dt = 1 / C · dC

When the left side of the equation is integrated from 0 to t, and the right side is integrated from C ₀ to C, and t is obtained, −１ ／ · V ′ / V ₀ .t = Log (C / C ₀ ) T = 3 · V ₀ / V ′ · Log (C ₀ / C) Assuming that the time when the volume V _{0 of the} tank 1 is replaced by the water having the volume V ₀ is T ₂ , T ₂ = V ₀ / V = 3 · V ₀ / V ′. Here, the initial OH ^- concentration of the liquid in the tank 1 is represented by C
_Assuming that _OH0 and the OH ^- concentration of the liquid in the tank 1 are C _OH ,
The equation is: t = 3 · V ₀ / V ′ · Log (C _OH0 / C _OH )
... '. PH in tank 1 is 1
The time required to change from 2 to 9 (the required processing time) is T
When _P, 'expressions and formulas _{from, T P = 3 · V 0} / V'· Log (C OH0 / C OH) = T 2 Log (C OH0 / C OH) ··· . On the other hand, C _OHO = 10 ^-2 (OH ^- mol / L),
Since C _OH = 10 ⁻⁵ (OH ⁻ mol / L), the formula is as follows: T _P = 3 · T ₂ (10) Therefore, also in this case, when V ₀ is replaced with water for three times, the pH changes from 12 to 9.

Here, if the material balance in the membrane separation device 3 is obtained, V ′ = V + V _{C. According} to the experimental data obtained by the inventor, the average permeation flow rate at a concentration of 10 to 15% is 180 L / V.
m ² / hr, V _C = ² V ′ / 3, and V = 180 A, so V ′ = 540 A. By substituting this value into the equation, T _P = V ₀ / 180A is obtained. Thus, the processing time T _P by the vibrating membrane separation apparatus of the present invention is calculated from the equation (10) by T _P
P = 3V ₀ / 180A.

(3) Comparison between the processing time T ₀ when the conventional cross-flow type membrane separation device is used and the processing time T _P when the vibration type membrane separation device of the present invention is used. Comparing the obtained T _P with T ₀ , T _P =
The T ₀ /4.5. In other words, it can be seen that the use of the vibration type membrane separation device of the present invention enables processing in 1 / 4.5 (about 22%) of the conventional cross-flow type membrane separation device.

(4) Comparison of treatment time with actual machine Next, a slurry of calcium carbonate having a concentration of 6% by weight and a volume of 30 liters was applied to a membrane area of 1.41 m ² by a diafiltration method as shown in FIG. The processing time when washing from pH 12 to 9 using an ultrafiltration membrane of
A test was performed to compare the case where the conventional cross-flow type membrane separation device was used and the case where the vibration type membrane separation device of the present invention was used, and the results are shown in FIG. As shown in FIG. 6, according to the method of the present invention, it can be seen that the processing time is reduced to about 1/4 (25%) as compared with the conventional method.

[0020]

According to the method of the present invention, the permeation flux is high, fouling to the membrane surface is prevented, the treatment of a high-concentration slurry is possible, and the slurry can be washed with high efficiency.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a diafiltration method.

FIG. 2 is a diagram illustrating fouling in a conventional cross-flow type membrane separation apparatus.

FIG. 3 is a diagram illustrating the concept of a permeation process by the vibrating membrane separation device of the present invention.

FIG. 4 is a view showing a schematic configuration of a slurry washing apparatus suitable for carrying out the method of the present invention.

FIG. 5 is a sectional view showing a part of the vibration type membrane separation device of the present invention.

FIG. 6 shows a case where a vibration type membrane separation device of the present invention is used and a case where a conventional cross flow type membrane separation device is used.
It is a figure which compares the processing time by a diafiltration method.

[Explanation of symbols]

 9 ... supply tank 10 ... pump 11 ... filter pack 12 ... torsion bar 13 ... storage tank 14 ... permeable membrane

Claims (1)

[Claims] 1. A pressurized slurry to be treated is supplied to one side of a pressure vessel partitioned by a permeable membrane, and the permeable membrane is vibrated to allow a permeated component to permeate to the other side and concentrated from one side. Remove the liquid and return this concentrate to the supply tank,
The permeated liquid is taken out from the other side, the permeated liquid is stored in a storage tank, the cleaning liquid is supplied to the supply tank, the slurry in the supply tank is pressure-fed to the pressure vessel, and the permeation process is performed. A method for cleaning a slurry, comprising repeating the above-mentioned treatment continuously until the slurry reaches a predetermined cleaning degree.