JP2009285545A - Method of mixing powdered polymer flocculant - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To mix two or more types of powdered polymer flocculants in a powder state to obtain a powdered polymer flocculant. <P>SOLUTION: A mixing method comprises arranging powder discharge outlets of at least two powder quantitative feeders 12a and 12b upstream of a screw type mixer 100 in the extruding direction of the screw, supplying individual powdered polymer flocculants from the powder discharge outlets of at least two of the powder quantitative feeders continuously to the screw type mixer 100 and mixing the powdered polymer flocculants while carrying downstream at least two types of powdered polymer flocculants by the screw of the screw mixer 100 and taking out the mixed powdered polymer flocculant from a downstream discharge outlet. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a powdery polymer flocculant mixing method for stably and uniformly mixing a powdery polymer flocculant.

  The polymer flocculant is made of a high-molecular weight water-soluble polymer, and can efficiently agglomerate and remove suspended fine particles in water.

  The polymer flocculant is a brand of polymer flocculants because it needs to respond to diversification of waste water, waste liquid, sewage, etc., and various types of wastewater treatment facilities and equipment that are newly developed every day with different functions. It is forced to produce a variety of products by segmentation.

  Conventional manufacturers of polymer flocculants select the polymerization conditions such as the amount of polymerization initiator, type of polymerization initiator, polymerization temperature, polymerization method, etc. The above requirement is answered by adjusting the molecular weight.

  In the brand classification of polymer flocculants, it is necessary to line up several brands of brands that differ only in the 0.5% salt viscosity, even with the same monomer composition, together with the composition of the monomers constituting the polymer flocculant. .

  Conventionally, the above requirements have been met by changing the polymerization conditions for each brand and carrying out strict manufacturing control.

  The brand classification of polymer flocculants is usually subdivided with 0.5% salt viscosity, and it is necessary to strictly control the polymerization conditions including light irradiation in order to achieve the planned 0.5% salt viscosity. Therefore, it is difficult to industrially manage production.

  Although it may be written as 0.2% melt viscosity in the product catalog, the result of 0.5% salt viscosity is actually converted to 0.2% melt viscosity. Table 1 below is an excerpt from the product catalog of MT Aqua Polymer Co., Ltd.

  There is an example in which a polymer flocculant having a different 0.5% salt viscosity is produced by changing the kind and strength of the polymerization initiator in the light irradiation with the same monomer composition (see Patent Document 1). It is industrially difficult to carry out polymerization while strictly controlling the polymerization conditions and controlling the 0.5% salt viscosity.

  In addition, there is an example (see Patent Document 2) in which the intrinsic viscosity is changed by changing the kind and strength of the polymerization initiator in the light irradiation with the same monomer composition, but the photopolymerization initiator is a single amount. If it is not uniformly dispersed in the body mixture, there are problems in production, such as a large variation in viscosity of the polymer.

  On the other hand, a polymer flocculant having a desired solution viscosity is produced by mixing polymer flocculants. As a mixing device, a planetary motion type mixer, a fluid mixing device using air, a container rotation type mixing device, and the like are used, but all mix powder in a batch type and have a mixing time. It is necessary for a long time, and as shown in a comparative example described later, it is difficult to mix uniformly in a short time, and industrial productivity is low.

  In addition, since both are batch-type mixing devices, if fractions occur in the product before mixing, it must be discarded, or there is an optimum charge amount due to the mixing performance of the batch-type mixing device, and it is constantly changing. It is impossible to produce only the necessary amount corresponding to the shipping amount to be produced, resulting in defective inventory.

Therefore, a continuous mixing method of a powdery polymer flocculant in which two or more powdery polymer flocculants are continuously mixed in a powder state to give a predetermined aqueous solution viscosity is not known.
JP 2001-335603 A (Example 1-6) JP-A-4-57682 (Example 1-3)

  An object of the present invention is a mixing method of a powdery polymer flocculant in which two or more kinds of powdery polymer flocculants are continuously mixed in a powder state, and a method capable of mixing extremely efficiently. It is to provide.

The present invention for achieving the above object is described below.
[1] A method for mixing powdery polymer flocculants in which at least two kinds of powdery polymer flocculants having different viscosities of an aqueous solution of a predetermined concentration are mixed in the form of a powder, and The powder supply ports of at least two powder quantitative supply devices are provided on the upstream side, respectively, and a predetermined amount of powdery polymer flocculant is continuously supplied from the powder supply ports of the at least two powder quantitative supply devices. The at least two types of powdery polymer flocculants are mixed downstream while being fed to the screw-type mixer at a speed and at least two types of powdery polymer flocculants are conveyed downstream by the screw of the screw-type mixer. A method for mixing a powdery polymer flocculant, wherein at least two kinds of mixed powdery polymer flocculants are taken out from a discharge port provided on the side.

  According to the mixing method of the powdery polymer flocculant of the present invention, since two or more kinds of powdery polymer flocculants can be continuously and uniformly mixed in a powder state, the quality of the powdery polymer flocculant is important. It is possible to easily obtain a powdery polymer flocculant mixture having an item 0.5% salt viscosity as a preset value.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows an example of a screw mixer used in the method for mixing a powdery polymer flocculant of the present invention. In the screw mixer 100, a screw 6 in which a spiral rotating blade 4 is formed in a cylindrical casing 2 is accommodated. The rotating shaft 8 of the screw 6 is rotated by the rotational force of the motor 10. A plurality (two in this example) of powder quantitative supply devices 12 a and 12 b are installed on the upstream side of the screw-type mixer 100 in the screw extrusion direction X. In the powder quantitative supply devices 12a and 12b, reference numerals 13a and 13b denote hoppers for respectively charging powdery polymer flocculants to be mixed. Feeders 14a and 14b are attached to the lower ends of the hoppers 13a and 13b. The feeders 14a and 14b quantitatively and continuously supply the powdery polymer flocculant in the hoppers 12a and 12b to the supply pipes 16a and 16b. The supply pipes 16 a and 16 b are supply pipes connected at one end to the outlet sides of the feeders 14 a and 14 b, and the supply ports 18 a and 18 b at the other end are connected to the upstream side of the casing 2.

  Reference numeral 20 denotes a discharge pipe connected to the downstream side of the casing 2, and the mixed powdery polymer flocculant mixture is taken out from a discharge port 22 at the lower end of the discharge pipe 20.

  The supply ports 18a and 18b are preferably provided on the upstream side of the casing 2 as much as possible, and the mixing efficiency decreases as the supply ports 18a and 18b are provided on the downstream side. The supply ports 18 a and 18 b are preferably provided at least upstream of the center of the casing 2.

  The powdery polymer flocculant in the hoppers 13a and 13b is continuously fed to the supply pipes 16a and 16b at a predetermined flow rate by the feeders 14a and 14b, and is fed into the casing 2 through them. The powdery polymer flocculant sent into the casing 2 is sent downstream (in the direction of the arrow X) by the rotating blade 4 rotating in the casing 2 and the powdery polymer flocculant is mixed. The powdery polymer flocculant sufficiently mixed in the casing 2 passes through the discharge pipe 20 provided on the downstream side in the casing 2 and is taken out from the discharge port 22 to the outside.

  The mixing ratio of the powdery polymer flocculant is determined by the feeding speed of the feeders 14a and 14b.

  In the above example, two powder quantitative supply devices 12a and 12b are provided. However, the present invention is not limited to this, and a powder quantitative supply device can be provided according to the number of powdery polymer flocculants to be mixed. .

  Furthermore, although the single screw type mixer was used as the screw type mixer, a multi screw type mixer having two or more screws in the casing may be used.

  As the powdery polymer flocculant, a powdery one can be used among the polymer flocculants used in the coagulation and dehydration treatment of sludge and wastewater. Any of cationic, anionic, nonionic and amphoteric can be used.

  There is no restriction | limiting in particular as an average particle diameter of the powdery polymer flocculent to be used. The average particle size is preferably 100 to 200 μm from the viewpoint of ease of dissolution in water. The molecular weight is not particularly limited.

  In addition, as a polymer flocculant, in general, in addition to powder, liquid and emulsion are commercially available. The powdery polymer flocculant has an advantage that the storage stability is better than the liquid or emulsion type, and the performance is not easily deteriorated during storage.

  When two kinds of powdery polymer flocculants are mixed, the mixing ratio (mass ratio) is preferably 90/10 to 10/90, and more preferably 70/30 to 30/70. When one side exceeds 90 mass%, there exists a possibility that a mixing effect cannot fully be expressed.

  Moreover, since the period of a solution state can be shortened by melt | dissolving and using a powdery polymer flocculant at the time of use, degradation of the performance of flocculant aqueous solution can be suppressed. Furthermore, since it is a powder, there are advantages such as low transportation costs and a small number of places required for storage.

Example 1
Two kinds of powdery polymer flocculants were mixed using the powdery polymer flocculent continuous mixing apparatus shown in FIG.

  The powdery polymer flocculant continuous mixing apparatus 100 accommodates the rotary blades 4 having a diameter of 20 cm and a length of 2 m in the casing 2, and the pitch of the rotary blades was 10 cm. The rotation speed of the rotary blade 4 was kept at 60 times / minute.

  The powdered polymer flocculant A (methyl chloride quaternized product of dimethylaminoethyl acrylate = 60 mol% / acrylamide = 40 mol%, 0.5% salt viscosity 29.0 (mPa / s)) was supplied and supplied to the supply pipe 16a at a supply rate of 5.01 kg / min. At the same time, powdery polymer flocculant B (dimethylaminoethyl methacrylate methyl chloride quaternized compound = 100 mol% polymer, 0.5% salt viscosity 11.8 (mPa / s)) was charged, and the supply rate was 11.69 kg. / Min. To the supply pipe 16b.

  Thereafter, the mixture taken out from the discharge port of the screw mixer was sampled to obtain samples 1-1 to 1-6. The dry residue and 0.5% salt viscosity of these samples were measured, and the mixing rate was calculated.

Measuring method of dry residue The amount of aluminum cup is precisely weighed (W1 g). The tare is removed, and the sample is placed in an aluminum cup of about 2.0 g and precisely weighed (W2 g). Next, the sample is dried for 90 minutes in a hot air circulating dryer at 105 ± 0.5 ° C. Thereafter, the mixture is allowed to cool in a desiccator for about 15 minutes and weighed again (W3 g). Following formula (1)
Dry residue (wt%) = (W3g−W1g) ÷ W2g × 100 (1)
To obtain the dry residue.

0.5% Salt Viscosity Measurement Method Accurately weigh 500.0 g of distilled water in a 500 ml poly beaker, add 20.8 g of reagent grade 1 sodium chloride, and dissolve with stirring while adjusting the rotation speed of the jar tester to 200 rpm. . 2.77 g of a sample is accurately weighed in an aluminum cup, and the sample (powdered polymer flocculant) is gradually added to a poly beaker so as not to become mamaco. Viscosity is measured after stirring and dissolving for 4 hours. At this time, stirring is temporarily stopped after 2 hours and 3 hours in the middle of dissolution, and the gel-like material adhering to the blade is scraped off. A poly beaker is placed in a thermostatic water bath (25 ° C.), and the temperature of the solution is adjusted to 25 ± 0.5 ° C., and then the viscosity is measured using a dedicated viscometer. Measurement conditions of the dedicated viscometer are 60 rpm, measurement time 5 minutes, measurement temperature 25 ± 0.5 ° C., and measurement rollers No 1 and No 2. The value on the scale plate of the viscometer pointer after 5 minutes is read to one decimal place.
Rotor No. 1 used 0.5% salt viscosity (mPa · s) = reading x 94 ÷ dry residue (wt%) (2)
Using rotor No. 2 0.5% salt viscosity (mPa · s) = reading x 5 x 94 ÷ dry residue (wt%) (3)
To determine the measured viscosity value of the solution.

Measuring method of mixing ratio The mixing ratio is obtained by the following formula (4).

0.5% salt viscosity of mixed polymer flocculant (calculated value) = 0.5% salt viscosity of A × A content (wt%) / 100 + B 0.5% salt viscosity × B content (wt %)
Mixing ratio = (0.5% salt viscosity (actual value) /0.5% salt viscosity (calculated value)) × 100 (4)
The measurement results are summarized in Table 2.

Example 2
The same operation and measurement as in Example 1 were performed except that the supply rate of the polymer flocculant A was changed to 8.35 kg / min and the supply rate of the polymer flocculant B was changed to 8.35 kg / min. The measurement results are summarized in Table 2.

Example 3
The same operation and measurement as in Example 1 were carried out except that the feeding rate of the polymer flocculant A was 11.69 kg / min and the feeding rate of the polymer flocculant B was 5.01 kg / min. The measurement results are summarized in Table 2.

Comparative Example 1
The powdery polymer flocculant was mixed batchwise using a fluid mixing device with air. This fluid mixing device is a device for mixing by blowing air into the mixing tank from the lower end of the mixing tank and blowing up the powdered polymer flocculant inside. In a mixing tank of a fluid mixing device (air blender) with an internal volume of 3500 l, polymer flocculant B (homopolymer of dimethyl quaternary methyl chloride quaternary polymer) 1285 kg, polymer flocculant A (dimethylaminoethyl acrylate chloride) 560 kg of methyl quaternized product = 60 mol% / acrylamide = 40 mol% copolymer) was charged, and air (air pressure = 0.45 Mpa or more) was blown and mixed 18 times.

  The time required for 18 mixings was 18 minutes. Sampling was performed 12 times after air blowing mixing (mixing time was 12 minutes), 16 times, and 18 times later. The measurement results are summarized in Table 3.

Comparative Example 2
Powder polymer using a planetary motion type mixer equipped with a screw stirrer that precesses along the inner wall of a conical stirrer whose diameter gradually decreases toward the lower end (V-Nauta mixer internal volume 3000 l made by Hosokawa Micron). The flocculant was mixed. First, 1180 kg of polymer flocculant B and 500 kg of polymer flocculant A were charged into the same mixer and mixed for 20 minutes.

  Sampling was performed after 12 minutes, 16 minutes, 18 minutes, and 20 minutes. The mixing rate of the mixed powdery polymer flocculant sampled after 20 minutes was 82.4%, and only a product with insufficient mixing was obtained.

  The measurement results are summarized in Table 3. The mixer was operated at a rotation speed of 60 times / minute and a revolution speed of 0.8 times / minute.

Comparative Example 3
The blender shown in FIG. 2 was used. This blender mixes the contents by rotating a V-shaped mixing container 32 attached to the rotary shaft 30. 635 kg of polymer flocculant B and 285 kg of polymer flocculant A were charged into a container rotating type mixer (V blender manufactured by Nishimura Machinery Co., Ltd., internal volume 2000 l) and mixed for 20 minutes.

  The mixer was operated at a rotation speed of 12 times / minute. Sampling was performed after 12 minutes, 16 minutes, 18 minutes, and 20 minutes. The mixing ratio of the sample after 20 minutes was 83.0%, and only a product with insufficient mixing was obtained. The measurement results are summarized in Table 3.

It is a side view which shows an example of the powdery polymer flocculent continuous mixing apparatus used with the mixing method of this invention. It is explanatory drawing which shows the blender used in the comparative example 3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Screw type mixer 2 Casing 4 Rotating blade 6 Screw 8 Rotating shaft 10 Motor 12a, 12b Powder fixed quantity supply apparatus 13a, 13b Hopper 14a, 14b Feeder 16a, 16b Supply pipe 18a, 18b Supply port 20 Discharge pipe 22 Discharge port 30 Rotating shaft 32 Mixing container

Claims (1)

  A method of mixing a powdery polymer flocculant in which at least two kinds of powdery polymer flocculants having different viscosities of an aqueous solution of a predetermined concentration are mixed in a powder state, and on the upstream side of the screw extrusion direction of a screw type mixer The powder supply ports of at least two powder quantitative supply devices are respectively provided, and the powdery polymer flocculant is continuously screwed at a predetermined supply rate from the powder supply ports of the at least two powder quantitative supply devices. The at least two types of powdery polymer flocculants are mixed and provided on the downstream side while being fed to the mixer and at least two types of the powdery polymer flocculants are conveyed downstream by the screw of the screw mixer. A method of mixing a powdery polymer flocculant, wherein at least two kinds of mixed powdery polymer flocculants are taken out from the discharge port.

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