JPH031066B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for efficiently washing particulate matter having an affinity for liquids, such as synthetic fibrids and slags.

Prior Art Generally, when cleaning particulate matter, a method is used in which the particulate matter is mixed with a cleaning liquid such as water, and then the particulate matter and the cleaning liquid are separated. However, if the particulate matter to be cleaned has an affinity for the cleaning liquid, a large amount of the cleaning liquid remains inside the particulate matter and/or in the gaps even after the cleaning liquid is separated, so repeated cleaning is not necessary. However, this cleaning method is inefficient.

For example, in synthetic fibrids (pulp-like particles) produced by a wet method, even after dehydration, water containing a large amount of solvent remains 10 to 30 times as much as the fibrids, and this is removed by the method described above. Even if it is washed with 100 times more water, the amount of residual solvent will only decrease to 1/3 to 1/5.

As a method to improve this, after solid-liquid separation, the solids (particulate matter to be washed) are deliquified (water squeezed).
After that, there is a method of repeating the above-mentioned cleaning. That is, it is a method of repeating mixing → separation → deliquing (water squeezing) [→mixing → separation → deliquing (water squeezing)] → mixing → separation → deliquing (water squeezing). However, with this method,
If the object to be washed has a high affinity with the washing liquid,
It is difficult to reduce the amount of residual liquid and is not necessarily an efficient method.

For this reason, replacement cleaning is being considered as an alternative method. This method replaces the liquid contained in the layer of particulate matter with the cleaning solution by flowing a slow cleaning solution through a layered liquid-containing material made of particulate matter.Theoretically, the particulate matter layer It is said that cleaning can be completed with a cleaning solution that is equivalent to the amount of liquid (in practice, it is about 1.5 to 2.5 times as much) ("Chemical Engineering Handbook" 3rd edition, 933~
934 pages). However, even with this method, if the liquid content is 20 to 30 times that of particulate matter, such as synthetic fibrids, 30 to 75 times as much washing liquid is required.
Not economical.

On the other hand, washing in a centrifuge is also known.

Examples include cake washing in a Bart centrifuge, washing in a dehydration tank of a household electric washing machine, and the like.
It is thought that this method is more advantageous in cleaning as the amount of liquid (residual water) is small. However, even with this method, (a) many of the materials that are difficult to remove, such as fibrids and slugs, are not necessarily easy to homogenize in the particulate matter layer in the centrifuge, and short-circuit paths of the liquid are likely to occur; (b) ) It is difficult to adjust the actual passage (exchange) rate of the liquid, and (c) It is difficult to remove the particulate matter layer (object to be cleaned) by continuous operation. This is not necessarily a preferable method for cleaning particulate matter.

Purpose of the Invention The main purpose of the present invention is to provide a method for efficiently cleaning particulate matter that is difficult to clean due to its affinity with liquids with a small amount of cleaning liquid. An object of the present invention is to provide a cleaning method that is easy to handle after cleaning.

Composition of the Invention In order to achieve the above-mentioned object, the present inventors, as a result of intensive research, compressed an object to be washed containing a liquid and particulate matter having an affinity for the liquid, and removed the particulate matter in the pressed state. We have discovered that by forcibly passing the cleaning liquid through the layer, it is possible to perform efficient cleaning with a relatively small amount of cleaning liquid, and the ease of handling after cleaning can also be improved, and we have arrived at the present invention. It is something.

That is, in washing particulate matter coexisting with an affinity liquid, the present invention squeezes the particulate matter and forcibly passes the cleaning liquid through a layer of the squeezed particulate matter. This method is characterized by washing.

In the present invention, particulate matter that coexists with a liquid that has an affinity for the object to be cleaned refers to a particulate matter that coexists with a liquid (particularly a cleaning liquid) due to the composition, shape, structure, etc. of the particulate matter.
A general term for particles or aggregates thereof that are difficult to remove due to their high affinity with Examples of such particulate matter include Tokoku No. 11851 (1973) and Tokoku No. 11851 (1972),
Synthetic fibrids (pulp-like particles) by a wet method as described in No. 20421, Japanese Patent Publication No. 52-12803, etc.
Examples include fibrids (pulp-like particles) obtained by mechanically beating fibers, films, etc. that are easily formed into fibrils, such as those described in JP-A-51-8203. Among these fibrids, those mainly composed of aromatic polyamides such as polymetaphenylene isophthalamide and polyparaphenylene terephthalamide are particularly preferred.

Other examples of the particulate matter include slag, cotton sludge, and excess sludge. The shape of the particles is not particularly limited, and may be spherical or polyhedral, or may be a flake-like shape having branched fibers such as fibrids or fibrils.

These particulate materials have a high affinity for water due to their composition, shape, structure, etc., and usually contain about 10 to 20 times or more water than the particulate materials.

According to the present invention, when washing such particulate matter with a washing liquid such as water, first, the liquid-containing particulate matter to be washed is mechanically compressed to form a layer;
Next, a cleaning liquid is forced to flow through the compressed layer of particulate matter to replace the liquid contained in the object to be cleaned with the cleaning liquid, thereby cleaning the object.

The degree of squeezing varies depending on the type of material to be washed and the liquid content, but in the case of synthetic fibrids, it is generally preferable to squeeze so that the liquid content is reduced to 10 times or less than the particulate matter. However, excessive squeezing is not preferable because it becomes difficult to circulate the washing liquid into the squeezed layer. Normally, water at room temperature or heated water is used as the washing liquid, but other washing liquids may be used depending on the type of the object to be washed. The flow rate and pressure of the washing liquid should be selected appropriately depending on the type, amount, squeezing condition, etc. of the material to be washed, but in the case of synthetic fibrids, generally about 5 to 5
It is preferable to flow a washing liquid of 5 to 30 times the amount of fibrids for 10 minutes, and the pressure of the washing liquid is preferably 3 to 70 kg/cm ² .

In the present invention, when washing in the squeezed state as described above, it is possible to adjust the degree of squeezing, adjust the injection pressure of the washing liquid, and furthermore, provide valves in the washing liquid supply section, waste liquid discharge section, etc. It is preferable to adjust the opening/closing state and appropriately control the flow rate of the cleaning liquid to select conditions that allow for the most efficient cleaning. The number of times of washing is not limited to one time, but may be multiple times as necessary.

If the pressed material to be washed has a dense cake layer that is difficult to pass liquid through, it may be granulated in advance and then pressed and washed as a cake layer. In this case, it is preferable to deliquify the slurry containing particulate matter, press it, make it into a cake, crush it into granules, and then press it again and wash it. It is also possible to employ other granulation methods such as.

Next, one embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing an example of a cleaning device for implementing the present invention, and FIG. 2 is a sketch showing an example of the shape of a particulate matter aggregate after cleaning according to the present invention.

In Fig. 1, 1 is a cylindrical pressure-resistant container, 2a and 2b are a pair of pressure plates, and the pressure side of each pressure plate is composed of perforated plates 3a, 3b or wire mesh (not shown), respectively, and the back side thereof The sides are provided with spaces 4a and 4b for introducing and introducing liquid. At least one of the pressure plates is moved in the direction of the arrow by a pressure device 5 to squeeze the object P present between the pressure plates 2a and 2b. Further, 6a and 6b are drain pipes, and 7 is a washing liquid supply pipe, the latter of which is connected to a washing liquid pumping device 8.

When cleaning according to the present invention, the pressure plate 2
A material to be washed (such as a slurry of particulate matter) P is placed in the space between a and 2b, and the material to be washed P is appropriately squeezed by lowering the upper press plate 2a using the pressurizing device 5.
At this time, the water squeezed from the slurry is drained from the drain pipe 6.
It is discharged to the outside from a and 6b. Next, a high-pressure cleaning liquid is supplied from the cleaning liquid supply pipe 7, and the cleaning liquid is forced to flow from the upper perforated plate 3a through the layer of the pressed object P to the lower perforated plate 3b, and is washed and discharged. The liquid is discharged to the outside from the drain pipe 6b.

This operation is performed once or several times to complete the cleaning. After washing is completed, the washed cake-like particulate matter aggregate is taken out. This assembly has a compact cylindrical or disk shape as shown in FIG. 2, and is easy to handle.

In the above-mentioned operation, when injecting the cleaning liquid, an excessive injection pressure is required, or (and) a large portion of the cleaning liquid comes into contact with the cake-like object to be cleaned P and the inner wall of the cylindrical pressure vessel 1. If it is difficult to carry out actual cleaning due to the cleaning being carried out between the cleaning parts, the material to be cleaned P is granulated in advance into granules of an appropriate size.
It is preferable to charge the cleaning liquid evenly into the space inside the cylindrical pressure-resistant container 1, squeeze the layer consisting of this granular aggregate, and inject the cleaning liquid. For example, when washing a slurry of synthetic fibrids, the slurry is once dehydrated and pressed, a cake-like product obtained is mechanically crushed into granules, which is then pressed again and washed. is appropriate. In addition, in the present invention, the cake-like material that has been appropriately squeezed during washing may be further compressed again after washing to make the cake-like material hard or to reduce the amount of washing liquid in the cake-like material.

The cake-like product after washing can be sent as it is or after further drying, packaged and sent to the next process, or it can be crushed and used in the form of granules if necessary.

Functions and Effects of the Invention In generally known displacement cleaning, cleaning is performed by successively replacing the liquid existing between particles in a particle layer with new liquid. By flowing pressurized washing liquid and gradually (slowly) replacing the liquid around the particulate matter, the liquid trapped in the particulate matter can also be replaced, especially for flaky synthetic fibrids. This effect is remarkable in the case of particulate matter with a large specific surface area.

Therefore, according to the method of the present invention, even particulate matter that conventionally required an extremely large amount of cleaning liquid to be completely cleaned can be completely cleaned with a relatively small amount of cleaning liquid.

For example, synthetic fibrids made of polymetaphenylene isophthalamide can be produced by dissolving the polymer in an organic solvent such as N-methylpyrrolidone or N,N'-dimethylacetamide using a special device (for example, Japanese Patent Publication No. 40-9044). It is formed by discharging it into a coagulation bath (for example, N,N'-dimethylacetamide aqueous solution, glycerin, etc.) using a device described in JP-A-52-15621, etc., and causing precipitation. When the fibrids are filtered out by the usual method from the fibrid slurry obtained in this way, it is approximately 20%
~30x more liquid remains. This is approximately
Even if dispersed in 100 times the amount of water and filtered again after mixing, approximately
1.5x solvent remains. At this time, even if the liquid content is forcibly squeezed to about 5 times its content before dispersing it in water, 30 to 40% of the solvent remains based on the fibrids, so this is essentially removed. requires several hundred times more cleaning solution.

In contrast, according to the washing method of the present invention, fibrids can be almost completely washed with a washing solution that is 10 to 15 times larger or less, and the amount of washing solution required for washing can be significantly reduced. It becomes possible.

Further, since the particulate matter washed by the washing method of the present invention is a cake-like compact aggregate, it is extremely easy to handle and can be packed and transported as is. Therefore,
Another advantage is that cleaning and productization (packing preparation) can be integrated.

Examples Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples, but the present invention is not limited by these.

Example 1 A polymer was produced by gradually adding a solution of 5 moles of terephthalyl chloride and 95 moles of isophthaloyl chloride dissolved in tetrahydrofuran to a solution of 100 moles of metaphenylenediamine dissolved in tetrahydrofuran while stirring. did.
After neutralizing, washing with water, and drying, this polymer was dissolved in N-methylpyrrolidone (NMP) to increase the polymer concentration.
Using the apparatus described in JP-A-52-15621, this dope was added to 30% by weight of NMP.
Fibrids (pulp-like particles) were obtained by mixing with an aqueous solution and precipitating the polymer.

After washing this fibrid with a large amount of water, JIS
The shot par rigler freeness was measured using P8123 and found to be 58°SR.

Next, 4 parts by weight of aromatic polyamide fiber "Konex" (registered trademark) having a fineness of 1.5 de and a cut length of 6 mm and 6 parts by weight of the fibrid were thoroughly mixed,
Paper was made using a wet method to obtain a paper-like sheet of 120 g/cm ² .
The tensile strength of synthetic paper heated and pressurized at 280℃ is
7.5g/mm ² , elongation at break 18%, breakdown voltage (B.
DV) was 32KV/mm.

In addition, when the fibrids are filtered using a Nutsuchie filter, the moisture content of the bales measured according to JIS P8101 is 96.5%.
(i.e., 1 fibrid to 27.6 water).

On the other hand, the original fibrid slurry obtained in the fibrid manufacturing process was placed in a cylindrical pressure-resistant container with perforated plates made of sintered metal on the top and bottom, and was pressurized. The water was squeezed to 8). Water was successively injected into this compressed layer consisting of 40 parts by weight of pulp and 320 parts by weight of water, and the NMP concentration in the water discharged at that time was as follows. Cumulative amount of water injected NMP concentration in discharged water 50 parts by weight 50 parts by weight 33.5 parts by weight 50 100 33.5 100 200 28.5 100 300 14.0 100 400 4.3 200 600 2.5 As a result of analyzing various samples of the fibrid cake after washing with water, NMP The remaining amount is 1.2 to 2.2
It was in weight%. Moreover, the obtained cake was cylindrical and easy to handle.

This fibrid cake was redispersed and its freeness was measured to be 57°SR, and the physical properties of the paper-like sheet made in the same manner as above were as follows: tensile strength 7.4
g/mm ² , elongation at break 19%, and BDV 31.5 KV/mm.

Example 2 The same fibrid raw slurry as in Example 1 was
The bales were placed in a cylindrical pressure-resistant container similar to that in Example 1 and pressurized, and the bales were squeezed to a moisture content of 89% (ie, 1 part fibrid to 8 parts water).

This compressed dehydrated pulp is put into a crusher and crushed.
It was made into granules with an average particle diameter of about 3 mm. This was put into the container again and pressurized again, and the bale was squeezed to a moisture content of 75% (ie, 1 part fibrid to 3 parts water).

40 parts by weight of fibrids thus formed,
240 parts by weight of water was press-injected into a cake layer containing 120 parts by weight of water while continuing to pressurize it, and after passing through the cake layer, it was discharged for washing with water. The cake layer at the time of completion of water passage also contained 40 parts by weight of fibrids and 120 parts by weight of water.

The average amount of NMP remaining in the fibrid cake after washing with water was 2.4% by weight.

In addition, this fibrid cake was washed with water and then pressed again to achieve a bale moisture content of 50% (that is, 1 part of water to 1 part of fibrid).

These fibrid cakes were dispersed in a pulverizer into a 0.2% slurry with a beating degree of 60° SR, and 40 parts by weight of aromatic polyamide fibers similar to those in Example 1 were added to 60 parts by weight of fibrids and mixed and dispersed.
A paper-like sheet of 120Kg/mm ² was made. The physical properties of synthetic paper after heating and pressurizing at 280℃ are tensile strength of 7.2.
~7.8g/ ^mm2 , elongation at break 18~20%, BDV28~
It was 32KV/mm.

Comparative Example 1 Fibrids similar to those in Example 1 were separated and dehydrated using a Nutsche filter. After that, it was dehydrated in vacuum, and then it was thoroughly dehydrated by applying a sheet and pressing it, etc.
The fibrid cake after dehydration contained approximately 10 times more water than fibrids.

11 parts by weight of this cake (ie, 1 part by weight of fibrids) was thoroughly mixed with 100 parts by weight of water, and separated and dehydrated again using a Nutsche filter. The resulting cake is
The cake contained 10 parts by weight of water per 1 part by weight of fibrids, and the residual amount of NMP in the cake was 3.4%.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing an example of a washing device for implementing the present invention, and FIG. 2 is a sketch showing an example of the shape of a particulate matter aggregate (cake) after washing. In the figure, 1 is a cylindrical pressure vessel, 2a, 2b
3 is a pressure plate, 3a and 3b are perforated plates, 4a and 4b are spaces for liquid introduction and extraction, 5 is a pressure device, 6a and 6b are drain pipes, 7 is a cleaning liquid supply pipe, and 8 is a cleaning liquid pressure feeding device. show.

Claims (1)

[Claims] 1. In washing particulate matter coexisting with an affinity liquid, the particulate matter is squeezed and the cleaning liquid is forcibly passed through the layer of the squeezed particulate matter. 1. A method for cleaning particulate matter, which comprises cleaning by washing. 2. The method for washing particulate matter according to claim 1, wherein the particulate matter is a synthetic fibrid. 3 Particulate matter that coexists with a liquid that has an affinity for
The method for cleaning particulate matter according to claim 1 or 2, wherein the particulate matter is granulated in advance. 4 Particulate matter that coexists with a liquid that has an affinity for
The method for washing particulate matter according to claim 3, wherein the particulate matter is granulated by compression and pulverization.