JPS6352928B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a flocculant that has good solubility in water and is low in dust. Water-soluble acrylamide-based high polymers (hereinafter referred to as polymers) are widely used as flocculants, thickeners, sticky agents for paper manufacturing, and the like. Many of these polymers are manufactured and supplied in powder form. Since most of these polymers are used after being made into a low concentration aqueous solution of about 0.01 to 0.5%, it is necessary to dissolve them in water. When dissolving polymer powder in water, a method is used in which the powder is added little by little while stirring the water.For this purpose, an operator must directly perform the addition operation, or a special supply for the addition must be used. equipment is required. Despite this, so-called "mamako" tends to occur, and it is often seen that a very long time is required for dissolution. Furthermore, there are many cases in which the polymer powder absorbs moisture, resulting in a decrease in powder fluidity, or is classified, forming bridges inside the powder supply device, which impede stable supply. Furthermore, since the polymer powder contains fine particles, it scatters in the air as dust, worsening the working environment. Such fine powder requires treatment such as regeneration into granules by some means. Many proposals have been made in the past regarding methods for improving the solubility of polymer powders or for improving the solubility incidentally for the purpose of dust prevention. For example, a method of kneading water or a water-containing hydrophilic solvent with polymer flocculant powder and drying the mixture (Japanese Patent Application Laid-Open No. 49-1998-1)
83681), if the ratio of water to the powder is small, the adhesive granulation effect will be poor and it will be difficult to produce granules, and if the ratio is too large, it will become a so-called "dango"-like mass, which will cause damage to the vessel walls and stirring. Stable production is extremely difficult as adhesion to the blades occurs and drying time becomes extremely long. In addition, in the case of water-containing hydrophilic organic solvents, there are few problems in the kneading process, but in the drying process, when drying in a closed system to recover the organic solvent, as the solvent recovery progresses, "chirstone"-like formations occur in the dryer. Huge hard lumps form, which seriously impede drying and subsequent grinding. Furthermore, since this method employs a method of removing water or a water-containing hydrophilic solvent from the top, there is a drawback that the spray holes are likely to be clogged. especially
This is not suitable as a method for granulating powder with a large content of fine particles of 200 mesh or less. In addition, in the method of mixing an inorganic salt containing water of crystallization (Japanese Patent Application Laid-Open No. 50-13278), even when a small amount of an inorganic salt containing water of crystallization is added, the contact portion is mixed at the same time as it comes into contact with the polymer powder. This has the disadvantage that the mixing operation is significantly hindered by the progress of "dango"-like agglomeration. Even if this lump is pulverized by some method, it will remain granular for several days after production, but it will gradually solidify after that, causing problems in handling and solubility, making it unstable as a product. , has inferior practical value. Next, in the method of adding a deliquescent inorganic substance (Japanese Patent Application Laid-Open No. 53-34843), powdering can be prevented to some extent, but dispersibility and solubility in water are not improved, and adding a small amount is not effective. Moreover, since it contains a deliquescent substance, it is highly hygroscopic and has the disadvantage of caking during storage or handling. As a result of intensive research to eliminate the above-mentioned deficiencies of the prior art, the present inventors have discovered a polymer powder, a concentrated inorganic salt aqueous solution that does not substantially dissolve the powder, and a concentrated polyethylene glycol solution that does not substantially dissolve the polymer powder. By uniformly stirring and kneading the aqueous solution and pulverizing it, there is no need to add it to the water little by little.
Even if added all at once, it is easily dispersed in water and dissolved in a short time. In addition, there is extremely little dust scattering.
They discovered a flocculant that does not substantially generate dust and completed the invention. That is, (a) a water-soluble acrylamide-based high polymer powder (50 to 90 wt.
%), (b) a highly concentrated aqueous solution (9 to 49 wt%) containing one or more inorganic salts that do not substantially dissolve the above (a), and the salt concentration is 20 wt% or more; and (c) An average molecular weight of 2000 that does not substantially dissolve the above (a)
~40 of polyethylene glycol with ~20000
-70 wt% aqueous solution (1 to 10 wt%) and adjust the amount of water added within the range of 7 to 40 wt% based on the final polymer composition,
The essential ingredient is a water-soluble acrylamide-based high polymer composition obtained by stirring and kneading the mixture of (b) and (c) to form small agglomerates of 3 cm or less, and then pulverizing the mixture into 6 meshes or less. The present invention provides a flocculant with good solubility. The flocculant of the present invention does not substantially disintegrate the granules during normal transportation, storage, and handling, has good quality stability, and is extremely unlikely to solidify into a "dango" shape. Moreover, the flocculant of the present invention hardly adheres to the inner wall of the kneader or the stirring blades, and is extremely easy to take out from the kneader, resulting in good workability. Also, when dissolving, there is no need to add small amounts to water, and the entire predetermined amount can be added for a short period of time, e.g.
It is possible to add at a rate of Kg/min. If necessary, it is possible to prepare a concentrated viscous aqueous solution or aqueous gel with a concentration of 10wt% or more of the polymer, which is an essential component of the flocculant, without any problems and in a short time, and it is easily soluble or easily dispersible. Therefore, the solubility of polymer powder containing a large amount of fine powder can be significantly improved, which could not be achieved by conventional methods. Furthermore, as mentioned above, not only can the so-called "mako" be not generated during dissolution and it can be rapidly dissolved.
An extremely advantageous advantage is that no dust is generated, which is always a problem when handling fine powders. Therefore, the labor involved in the dissolution operation is significantly reduced and no special feeding equipment is required for the addition operation. There is a close relationship between the particle size of polymer powder and its solubility in water. The smaller the particle size, the faster the dissolution time, and at the same time, fine particles are closely related to the generation of so-called "mako" and dust. On the other hand, if the particle size is coarse, the problems of "mamako" and dust will be reduced, but the dissolution time will be significantly longer, which will be inefficient and will likely cause troubles such as clogging of the supply device. Therefore, during the production of polymer powder, efforts are being made to adjust the powder particle size within a certain range by pulverizing, sieving, classifying, and the like. Coarse particles can be re-pulverized and are not much of a problem, but fine particles, particularly fine powders of 200 mesh or less, cause the aforementioned "mamako" and dust generation, so their utility value is low if left as is. ,
This is preferable if production efficiency and economic efficiency are taken into consideration. A feature of the present invention is that the basic effects are achieved by using a highly concentrated aqueous solution of an inorganic salt. In the highly concentrated aqueous solution of the inorganic salt used in the present invention, the acrylamide-based high molecular weight polymer having ordinary water solubility does not substantially dissolve, but only provides a wet or slightly swollen state. In the method for producing a water-soluble acrylamide-based high molecular weight polymer composition which is an essential component of the flocculant of the present invention,
Stirring is indispensable, and the proper particle state, i.e., granules made up of fine particles, is moderately strong and does not disintegrate when handled, and when added to water, quickly disintegrates and disperses, resulting in good solubility. It is a necessary means to obtain. In addition, stirring and kneading are necessary because if a mixture of a highly concentrated aqueous solution and polymer powder is simply heated externally without stirring, the desired granule-like shape will not be achieved and the whole will become a spongy block. is clear. If the concentration of the inorganic salt aqueous solution is low and has the ability to dissolve the polymer powder, a hard "dango"-like gel is generated and the effects of the present invention cannot be exhibited. but,
In a highly concentrated aqueous solution with a salt concentration of 20 wt % or more, even if solid salts are present in the polymer powder, this will hardly pose a problem for the flocculant of the present invention. Examples of inorganic materials include KCl, K ₂ SO ₄ , K ₂ CO ₃ ,
_{NaCl , NaNO3} , _Na2CO3 , _Na3PO4 , _NH4Cl ,
(NH ₄ ) ₂ SO ₄ , CaCl ₂ , Ca(NO ₃ ), MgCl ₂ ,
Examples include MgSO ₄ , AlCl ₃ , Al ₂ (SO ₄ ) ₃ , etc.
Since polyvalent metal salts can sometimes make the polymer water insoluble, their range of use is severely limited. provides a highly concentrated aqueous solution with the properties necessary to produce a superior granular polymer composition;
Also, from the economical point of view of the amount used, sodium sulfate and sodium carbonate are most preferred in the present invention. In the present invention, if a highly concentrated aqueous solution (20 wt% or more) of alkali metal neutral salts of sulfuric acid and carbonic acid is used, it is possible to increase the content ratio of water-soluble acrylamide-based high polymer powder in the polymer composition. . This is important from the standpoint of storage stability of the obtained polymer composition, especially prevention of block formation during the storage period, as well as ease of kneading and pulverization in the manufacturing process of the polymer composition. It also has a lot to do with ease of use. Similarly, adjusting the water ratio to the entire polymer composition within the range of 7 to 40 wt% is also an essential requirement for exhibiting the effects of the present invention. In the method for producing a water-soluble acrylamide-based high polymer composition, it is desirable to control the temperature at 25 to 35°C.
At temperatures below 10°C, it takes a long time to knead the inorganic salt aqueous solution and polyethylene glycol aqueous solution with the polymer powder to form a small lump of fine particles appropriately aggregated. On the other hand, if the temperature is 50°C or higher, coarse lumps will rapidly form in the initial stage of kneading, requiring extra kneading operations to break them up into suitable small lumps, which may adversely affect quality. It is also important for manufacturing to always operate under constant conditions. Therefore, it is most preferable to carry out kneading and the like at 25°C to 35°C, which does not require excessive heating or cooling. Therefore, the high concentration inorganic salt aqueous solution of 20% or more as used in the present invention refers to the concentration at 25 to 35°C. In addition, polyethylene glycol aqueous solution (40~
70wt%) reduces the load on the stirrer during kneading,
It is an additive necessary to achieve the desired effect in a short time, and it also improves the grindability and is commonly used in general grinding, similar to dry polymers of water-containing kneaded product small lumps. Useful for machine processing. If the molecular weight of this polyethylene glycol is low, it will not be effective in terms of workability during grinding or kneading, and if the molecular weight is too high, it will not exhibit the desired effect. Therefore, in the present invention, polyethylene glycol having a preferable average molecular weight in the range of 2,000 to 20,000 is particularly effective. Since these are solid at room temperature, it is necessary to add them as an aqueous solution in order to mix them homogeneously, and a highly concentrated aqueous solution (40 to 70 wt%) that does not substantially dissolve the acrylamide polymer powder is particularly preferred.
The effects of the present invention can be fully exhibited when the amount of the polyethylene glycol aqueous solution added is in the range of 1 to 10 wt% based on the polymer composition. The present invention makes effective use of fine powder, which has low utility value with normal methods because it has a lot of dust and easily generates "mamako", and requires recycling treatment such as granulation, and is made possible by an inexpensive and simple method. As a result, a polymer composition that maximizes the characteristics of fine powder, is easily dispersible in water without any dust problems, and dissolves quickly can be obtained. The water-soluble acrylamide-based high polymer powder applicable to the present invention includes polyacrylamide, polyacrylamide partial hydrolyzate, acrylamide-acrylate copolymer polysodium acrylate, acrylamide-dimethylaminoethyl methacrylate, and/or its quaternary chemical compound copolymers, etc. Furthermore, the flocculant of the present invention can be widely used as a sludge flocculation accelerator, a dehydrating agent, a thickener, a paper-making sticky agent, and the like. Examples will be shown below, but the present invention is not limited thereto. Production example 1 30 kg of a 25% aqueous solution of sodium carbonate (30°C) and 5 kg of a 60% aqueous solution of polyethylene glycol with an average molecular weight of 4000 were placed in a 300 capacity double-arm kneader (SUS304) and mixed, and then polyacrylamide with an average molecular weight of 8 million was mixed. Powder (20-60 mesh 5
%, 60-200 mesh 52%, 200 mesh or less 43
%) 65Kg and mix at 100rpm. After about 5 minutes, it becomes a little viscous, but it gradually begins to form into small lumps, and after about 10 minutes, it has loosened into small lumps with a diameter of about 5 cm or less, and after 20 minutes, it has become a granular lump with a maximum diameter of about 2 cm or less. Summer. This was taken out from the kneader, and the entire amount was pulverized in a hammer mill (equipped with a screen having 2 mm diameter holes) for about 15 minutes to obtain moist granules in the form of agglomerated fine particles. This composition has 6 to 200 meshes 99.7% 200 meshes or less 0.3% Volatile matter (moisture) after drying at 105℃ for 120 minutes 28.9% 50g of tap water was instantly added while stirring with a paddle-shaped stirring blade at 50 rpm, but Mamako not generated,
Stirring was continued and a uniform viscous aqueous solution was obtained after 30 minutes. No dust was observed at all. Production example 2 25 in a stainless steel ribbon mixer with a total capacity of 4
% sodium sulfate aqueous solution (30℃) and 15 g of a 50% aqueous solution of polyethylene glycol with an average molecular weight of 10,000 were added, and while stirring at 80 rpm, acrylamide-dimethylaminoethyl methacrylate methyl chloride quaternized copolymer (50 mol%) copolymer was added. Powder (apparent average molecular weight approximately 2.3 million, 16 to 200 mesh)
62.8%, 200 mesh or less (37.2%)) was added in about 5 minutes, and stirring and kneading was continued for another 10 minutes to make sure that the entire particle mass was 1 cm or less and that they did not adhere to each other, and then the stirring was stopped. and removed from the ribbon mixer. Almost no adhesion was observed on the inner wall of the ribbon mixer and stirring blades after discharge. The taken out small lumps were ground in a feather mill using a 2 mm hole screen (moisture 23.6%).
Granules were obtained having a particle size of 99.7% 200 mesh and 0.3% below 200 mesh. There was no dusting at all before and after the crushing operation. Tap water in 2 beakers
2.9 g of this granular composition was added instantly while stirring at 100 rpm using a jar tester.
It was uniformly dispersed in water within seconds, and by continuing to stir for 15 minutes, a homogeneous aqueous solution was obtained. Production Examples 3 to 7 Prepared compositions were obtained in the same manner as in Production Example 2 at the proportions shown in Table 1. The test results of the obtained compositions are shown in Table 1 and Table 2 as a comparative control.

【table】

【table】

[Table] Example 1 Take 100 ml of 3% suspension of pharmacopoeial kaolin in a 100 ml graduated cylinder (100 ml corresponds to a depth of 21 cm), and add 0.01% of the granular polyacrylamide obtained in Production Example 1.
Add 1 ml of aqueous solution (1 ppm of turbid water), cap it, gently stir it upside down 10 times, let it stand, and measure the settling time required for the sedimentation interface of floc-formed kaolin to reach a depth of 10 cm from the liquid surface. At the same time, the turbidity of the supernatant water after 3 minutes of standing was measured by JIS-K0101, transmitted light measurement method. The results of comparison with those without flocculant additives were as follows.

[Table] Example 2 Mixed sludge of SS2.4% urban sewage in a 300ml beaker
Take 200 ml of the granular acrylamide-dimethylaminoethyl methacrylate methyl chloride quaternized copolymer (50 mol%) obtained in Production Example 2.
11 ml of 0.2% aqueous solution (110 ppm relative to sludge) was added and stirred 100 times with a spatula to cause flocculation. The entire amount of flocculated sludge was poured into a Buchner funnel lined with a nylon screen (96 mesh), natural filtration was performed, and the filtrate was received in a measuring cylinder and the amount of filtrate was measured over time and compared with that without flocculant additives. .

[Table] Example 3 Pour civil engineering waste mud into a 200ml beaker (mud water specific gravity
1.30) Take 100ml and add 15ml of 0.1% aqueous solution of the granular acrylamide-sodium acrylate (85:15 mol%) copolymer obtained in Production Example 3 (for muddy water).
150 ppm) and stirred for 10 seconds at 1000 rpm using a Triton WRC stirrer to coagulate. The entire amount of the coagulated mud water was poured into a Buchner funnel lined with a nylon filter cloth (9B, manufactured by Nakao Filter Co., Ltd.), dehydrated for 5 minutes at a degree of vacuum of 500 mmHg, and the water content of the treated cake was measured. The results of comparison with those without flocculant additives were as follows.

【table】

Claims (1)

[Claims] 1 (a) The maximum particle size is 16 mesh or less, and 200 mesh
Water-soluble acrylamide-based high polymer powder containing 70% or less of fine particles below the mesh size (50~
90 wt%), (b) a highly concentrated aqueous solution (9 to 49 wt%) containing one or more inorganic salts that do not substantially dissolve the above (a) and the salt concentration is 20 wt% or more; and (c ) An average molecular weight of 2000 that does not substantially dissolve the above (a)
~40 of polyethylene glycol with ~20000
-70 wt% aqueous solution (1 to 10 wt%) and adjust the amount of water added within the range of 7 to 40 wt% based on the final polymer composition,
The essential ingredient is a water-soluble acrylamide-based high polymer composition obtained by stirring and kneading the mixture of (b) and (c) to form small agglomerates of 3 cm or less, and then pulverizing the mixture into 6 meshes or less. A flocculant with good solubility.