JPH06335608A - Separation of solid matter from solid-liquid mixture and its device - Google Patents

Abstract

PURPOSE:To separate solid matter from a solid-liquid mixture easily lumping by bringing a travelling belt-like strip into contact with a solid-liquid mixture and damming the solid-liquid mixture on the surface of the strip by a restriction means. CONSTITUTION:A solid matter separator is installed near just before a coater at the end of supply piping on the pump outlet side and on this side of a header. A travelling belt-like strip 62 is brought into contact with a solid-liquid mixture, and the solid-liquid mixture on the surface of the strip 62 is dammed by a restriction means 61 to leave the solid matter therein. and a suspension including no solid matter is taken out as an associated stream of the strip 62. In such a manner, solid matter is removed from a solid-liquid mixture easily lumping.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for separating solids (used herein to mean harmful solids having a certain size or more) from a solid-liquid mixture such as high-concentration paint or high-viscosity slurry. The present invention also relates to an apparatus therefor, and particularly to a method for separating a solid content suitable for a solid-liquid mixture which easily causes agglomeration (blocking) and an apparatus therefor.

[0002]

2. Description of the Related Art Heretofore, as a means for separating solids from a solid-liquid mixture, a filtration method using a filter, a centrifugal separation method using a cyclone, etc. have been generally adopted. For example, various roll coaters are widely used as a device for continuously coating a metal strip with a coating material. In particular, a pair of squeeze rolls (squeezing rolls) are placed across the metal strip, and the coating liquid supplied to both the front and back sides of the metal strip by a spray nozzle or roll is sandwiched between the squeeze rolls installed downstream and extra coating is applied. The squeeze roll coater that removes the liquid is magnesium oxide (Mg
It is also a suitable coating means for coating highly viscous solid-liquid mixtures such as O and magnesia), coating materials with high concentration, resins, pigments, and other materials with poor coating properties.

FIG. 4 shows an example of a coating liquid supply system for coating magnesium oxide. 1 is a mixing tank, 2 is a primary filter, 3 is a circulation tank, 4 is a secondary filter, 5 is a pump, 7 is a coating liquid header, 8 is a coater, 10 is a liquid receiving pan,
Reference numeral 11 is a coating liquid supply pipe, 12 is a coating liquid return pipe, and S is a strip. The coating liquid is prepared in the compounding tank 1. That is, magnesium oxide powder and water are supplied to the mixing tank 1 and mixed. Here, the coating liquid is supplied from the header 7 to the coater 8 via the supply pipe 11 by the pump 5 after entering the circulation tank 3 through the primary filter 2 for separating impurities and solids and passing through the secondary filter 4. It The coater 8 is a normal roll coater or a squeeze coater, and the coating liquid header 7 continuously supplies the coating liquid to the strip S via the coater 8 or directly. The excess coating liquid applied is recovered from the liquid receiving pan 10, passed through the return pipe 12 and the primary filter 2 and then recovered in the circulation tank 3 for circulation and use.

By the way, certain powders of magnesium oxide and the like are not a completely dissolved magnesium oxide in a state of being made into an aqueous solution and transported in a pipe, but a slurry-like solid-liquid mixture. , Since fine particles are suspended and the surface of the particles is active as hydroxide, the phenomenon called blocking, in which particles adhere to each other and grow, easily adheres to the inner wall of pipes and valves. Things grow and clog pipes and filters,
It becomes impossible to transport.

Moreover, in the case of magnesium oxide slurry,
In the primary filter 2 and the secondary filter 4 described in FIG. 4, there is a phenomenon that the slurry cannot pass through the filter unless the mesh size of the filter is about 10 times larger than the solid particle size. It was difficult to remove solids with such a filter. Furthermore, such grown particles, particles of solidified particles that have peeled off, particles that aggregate with each other, etc., have a particle size of approximately 30 μm.
If you try to coat the slurry liquid containing the above, there is no problem on the back side (assuming the strip to be coated is running in the horizontal direction), but it is supplied to the front side. In a short time until the solid content in the coating liquid is applied, it settles in the coating layer and agglomerates and adheres to the strip surface, or is squeezed with a squeeze roll or the like along with fine particles and moisture to be applied and removed. As a result, especially when the line speed, which lengthens the residence time, is lowered, the surface is roughened, and a coating defect such as solid content is generated.

In order to deal with such a problem, the coating facility is once stopped to clean the inside of the pipe, or when it is desired to avoid stopping the line for cleaning, two pipes are installed and switched to operate. It was necessary to take measures such as

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to solve these problems and to provide a method for separating solids from a solid-liquid mixture which is prone to agglomeration and an apparatus therefor.

[0008]

Means for Solving the Problems In the squeeze type coating equipment for metal strips, the present inventor has found that the solid content in the supplied liquid is not caught in the squeeze part of the coater as the coating speed becomes faster, and remains on the front surface of the roll nip part. Paying attention to the fact that the supply slurry is applied in advance with a temporary squeeze coater having an endless strip belt, and only the adhering liquid on the belt surface that has passed through the squeeze roll as an accompanying flow of the strip belt is squeezed with a ringer roll. The present invention has been completed based on the finding that it should be supplied as.

That is, in the method for separating solids from a solid-liquid mixture according to the present invention, the solid-liquid mixture is brought into contact with a traveling belt-shaped strip, and the solid-liquid mixture on the surface of the strip is blocked by a squeezing means. It is characterized in that the solid content is left in this, and the suspension containing no solid content is taken out as an accompanying flow of the strip, and the thickness of the accompanying flow is changed by changing the running speed of the strip to separate the solid content. It is also possible to control the range of minutes.

Further, the apparatus for separating solids from a solid-liquid mixture according to the present invention comprises an endless strip belt running while being supplied with the solid-liquid mixture, and a squeezing roll for squeezing the solid-liquid mixture on the endless strip belt. It is characterized by having.

[0011]

[Operation] In the present invention, a speed-controllable endless strip belt, a squeeze roll, a ringer roll, a liquid supply header, a liquid receiving pan, etc. are installed in the solid-liquid mixture supply system. It has the same structure as the coater. FIG. 3 is a conceptual diagram for explaining the state of solid content separation on the squeeze roll nip portion entry side of the solid content separation device 6 of the present invention.

As shown in this figure, the squeeze roll 61
If, in the liquid pool on the front surface, the coating liquid that is pulled by the endless belt 62 and moves, for example, up to 50% of the belt speed is regarded as the associated flow, the film thickness t of the associated flow changes depending on the Reynolds number Re. However, assuming that the density of the slurry (coating liquid) is ρ, the viscosity is μ, and the belt speed is v, in general, from the relation of Re = t · v · ρ / μ, t = (Re · μ) / (V · ρ), and if Re, μ, and ρ are almost determined by the physical properties of the slurry, the belt speed v and the film thickness t are inversely proportional, and when v becomes large, t becomes the diameter of the solid content c in the slurry. When it becomes smaller than this, the solid content c is left behind and taken into this liquid pool portion, and cannot pass through the roll nip portion and is separated.

According to the present invention, the endless belt is coated with the stock solution for coating in advance in this way, and the solid content having a large particle size is separated by squeezing with a squeeze roll, and the separated suspension is treated with, for example, a metal strip. Since it can be supplied to the coating solution header of the coater facility, only the coating solution slurry containing no large particle size is supplied to the strip surface, and a good coating film is formed.

The solid content separation device of the present invention does not cause clogging unlike a filter because it does not have a mesh portion.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a metal strip coating line will be described with reference to FIGS. FIG. 1 is a piping system diagram, and those common to FIG. 4 are designated by the same reference numerals,
6 is a solid content separation device. That is, as is clear from comparison with FIG. 4, a solids separation device 6 having a structure similar to that of a squeeze roll coater is provided near the coater 8 at the end of the supply pipe 11 on the outlet side of the pump 5 and before the header 7. Is provided, only the coating liquid slurry containing no solid content having a large particle size is taken out and sent to the header 7, and the portion containing the remaining solid content is returned to the return pipe 12.
Other than that, the description is omitted because it is similar to FIG.
The meshes of the secondary filter 2 and secondary filter 4 are both 200μ
m.

FIG. 2 is a detailed view of the solid content separation device 6, where 61 is a squeeze roll, 62 is an endless strip belt,
63 is a ringer roll, 64 is a liquid supply header, and 65 and 66 are liquid receiving pans corresponding to the squeeze roll 61 and the ringer roll 63, respectively. In this example, the squeeze roll 61
Is a urethane rubber roll with a diameter of 200 mm and a body length of 1000 mm, and has a spiral groove on the surface with a pitch of 0.65 mm. The ringer roll 63 is similar in size and material to the squeeze roll 61, but has no groove on the surface. Nip pressure is 200 for both
It is kg.

The endless strip belt 62 has a width of 800 mm
The steel belt is endlessly supported by four pulleys, and is driven in the direction of the arrow by at least one of the pulleys. The running speed of the belt can be arbitrarily controlled by a driving device and its control device (not shown). The coating liquid containing the solid content blocked by the squeeze roll 61 is returned to the return pipe 12 via the liquid receiving pan 65.
On the other hand, the coating liquid slurry containing no solid content that has passed through the squeeze roll 61 is squeezed from the surface of the endless strip belt 62 by the next ringer roll 63, and fed to the header 7 via the liquid receiving pan 66.

A stock solution having a solid content of more than 30 μm and a weight ratio of 3.4% is fed to the solid content separating device 6, and the driving speed of the endless strip belt 62 is changed to 10, 30, 50, and 100 mpm to separate the solid content separating device. When the weight ratio of the solid content in the coating liquid slurry supplied to the header 7 which is the output side of 6 was measured, it was 3.2, 0.5, 0.03 and 0.02%, respectively, and as discussed above, the belt speed was high. It was confirmed that the solid content separation performance was better.

[0019]

According to the present invention, the solid content can be separated from a solid-liquid mixture such as magnesium oxide which tends to agglomerate, and even when such a coating solution is used, no coating failure occurs, clogging of the filter and uneven coating. It has an excellent effect that a uniform and good coating film can be formed on the surface of the strip without any problems.

[Brief description of drawings]

FIG. 1 is a system diagram showing an embodiment of the present invention.

FIG. 2 is a partial configuration diagram showing a solid content separation device in an example of the present invention.

FIG. 3 is a conceptual diagram illustrating a solid content separation situation in the present invention.

FIG. 4 is a system diagram showing a conventional technique.

[Explanation of symbols]

 1 Preparation Tank 2 Primary Filter 3 Circulation Tank 4 Secondary Filter 5 Pump 6 Solids Separator 61 Squeeze Roll 62 Endless Strip Belt 63 Ringer Roll 64 Supply Header 65, 66 Liquid Receiving Pan 7 Coating Liquid Header 8 Coater 10 Liquid Receiving Pan 11 Coating liquid supply pipe 12 Coating liquid return pipe S strip

Claims (3)

[Claims] 1. A method for separating solids from a solid-liquid mixture, which comprises bringing the solid-liquid mixture into contact with a traveling belt-shaped strip (62), and squeezing means (61) to form a solid-liquid mixture on the surface of the strip. A method for separating solids from a solid-liquid mixture, which comprises blocking the mixture to leave solids therein, and taking out a suspension containing no solids as an accompanying stream of the strip. 2. The solid content from the solid-liquid mixture according to claim 1, wherein the range of the size of the solid content to be separated is controlled by changing the traveling speed of the strip (62) to change the thickness of the accompanying flow. Separation method. 3. A solid-liquid mixture characterized by having an endless strip belt (62) running while being supplied with the solid-liquid mixture, and a squeezing roll (61) for blocking the solid-liquid mixture on the endless strip belt. Separator of solids from.