JP2538782B2 - Dustproof treatment method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dustproof treatment method for suppressing dusting of dusting powder that generates a large amount of dust.

2. Description of the Related Art It is known that a certain type of polytetrafluoroethylene is fibrillated into ultrafine fibers in the form of a spider web when subjected to compression-shearing under an appropriate temperature condition. Tokusho
No. 52-32877 mixes a highly dusting powdery material with an effective amount of a particulate fibrillating polytetrafluoroethylene resin, and said mixture may cause fibrillation of the polytetrafluoroethylene resin to about 20. Disclosed is a dust control method for powdered substances other than polytetrafluoroethylene resin, which comprises stirring and performing a compression-shear action at a temperature of up to 200 ° C. until a desired degree of dust control is achieved. Fibrillation of polytetrafluoroethylene resin is said to start at about 20 ° C, but 50 ° C to complete the fibrillation within an industrially practical time.
Above, more preferably, it is desirable to carry out compression-shear action by stirring at a temperature of 80 ° C. or higher. Therefore, when the temperature is low, it is necessary to apply external heat to heat it to 80 ° C or higher.
Requires thermal energy and heating equipment.

JP-A-60-191084 discloses that solid particles of polytetrafluoroethylene are dispersed in water in an amount required for an exothermic hydration reaction with quick lime, and the dispersion is added to quick lime and mixed and stirred to obtain heat of hydration reaction. A slaked lime with improved novelty, characterized in that the above-mentioned polytetrafluoroethylene particles are fibrillated by a compression / shear action by stirring, and the slaked lime particles produced by these fibrils are coated and aggregated with a web in the form of spider webs. A method for producing high quality fertilizer has been proposed. This method utilizes the hydration exothermic reaction of quick lime to give the temperature required for fibrillation of polytetrafluoroethylene, but the reaction that happens to generate heat of reaction by the target dusting powder Unless it is not a generally applicable method.

Problems to be Solved by the Invention As described above, in order to fibrillate the polytetrafluoroethylene resin dispersed in the dust-generating powder, it is necessary to stir at a temperature of about 80 to 200 ° C. and apply compression-shear force. However, when the dusting powder temperature is low, external heat must be applied to heat the powder, which requires thermal energy and heating equipment. An object of the present invention is to provide a dustproofing method that does not require external heat.

B. Structure of the Invention Means for Solving the Problems The dustproof treatment method of the present invention comprises mixing a dusting powder with a fibrillating polytetrafluoroethylene resin, a substance that generates reaction heat due to a hydration reaction, and water. It is characterized by stirring and raising the temperature of the mixture by the heat of hydration reaction to fibrillate the polytetrafluoroethylene resin by compression-shear action at the time of mixing / stirring, and capturing the dusting powder by this fibril. To do.

In the method of the present invention, the order of adding the dusting powder, PTFE, the substance that generates reaction heat by the hydration reaction, and water is not particularly limited. All of them may be added and mixed at the same time, or they may be added and mixed sequentially, or a mixture of some of them may be used in advance. However, when the substance that generates reaction heat due to the hydration reaction is first mixed with water, it is necessary to immediately add other components to carry out the method of the present invention.

Specifically, the following embodiments can be exemplified.

PTFE, a substance which generates heat of reaction due to hydration reaction, and water are simultaneously mixed with the dusting powder and stirred.

PTFE and a substance that generates reaction heat due to hydration reaction are mixed in advance with dusting powder, and then water is mixed and stirred, or dust is generated with PTFE and water mixed in advance. The substance that generates heat of reaction due to the hydration reaction is mixed and stirred.

After the PTFE and the dusting powder are mixed in advance, a substance that generates reaction heat due to a hydration reaction and water are mixed and stirred.

After mixing the dusting powder and the substance that generates heat of reaction by the hydration reaction in advance, mix PTFE and water and stir, or
Alternatively, after preliminarily mixing the dusting powder and water, PTFE and a substance which generates reaction heat due to a hydration reaction are mixed and stirred.

Examples of the substance that generates reaction heat by the hydration reaction include alkaline earth metal oxides, alkaline earth metal peroxides, calcium carbide, phosphating lime, calcium aluminate, calcium silicate, and gypsum.

All of these are substances that generate heat of hydration when hydrated to form a hydroxide, and serve as a heating source to raise the temperature to a temperature suitable for fibrillation of PTFE. In particular, since the volume expands and powders during hydration, it further promotes PTFE nofibrillation, which is preferable.

Which of these is used may be mixed with the target dust-generating powder, and one that is readily available and inexpensive can be selected.

In terms of availability and cost, alkaline earth metal oxides, namely MgO, CaO, SrO, BaO, mixtures thereof,
For example, dolomite calcined product (CaO.MgO) is preferably used.

When dustproofing powder is treated with fibrillated PTFE, the proper amount of PTFE mixed depends on the particle size, specific gravity, water content, etc. of the dusting powder to be treated. It is desirable to have 0.005-1% by weight of PTFE mixed with the body.

The substance that generates reaction heat by the hydration reaction is a mixture of the dusting powder and the dustproofing agent composition due to the reaction heat,
It is desirable to mix in an amount capable of raising the temperature to 50 to 300 ° C, preferably 80 to 200 ° C.

As the substance which generates reaction heat by the hydration reaction, in order to enhance the reactivity, it is preferable to use a material which is crushed so that it is usually 5 mm sieve full pass, preferably 2 sieve full pass.

Commercially available PTFE includes powdery ones having an average particle size of about 500 microns and aqueous suspensions. Any of these may be used in the present invention, but an aqueous suspension is preferable because it has better dispersibility.

When an aqueous suspension of PTFE is used, the substance that undergoes a hydration reaction is hydrated by the water in the aqueous suspension to form a hydroxide, and the heat of hydration causes the PTFE to partially fibrillate. However, this has the advantage that the dustproofing agent composition itself, which contains particles of a substance that undergoes a hydration reaction, is also non-dusting.

Action When dust-proofing dust-producing powder, apply PTF to dust-producing powder.
E, When a substance that generates reaction heat due to hydration reaction and water are mixed and stirred lightly, compression-shearing force is applied, PTFE is rapidly fibrillated by the temperature rise due to reaction heat, and dust is generated by the fibrils. The active powder is coated and aggregated with a spider web to obtain a dust-proofed powder.

If the dust-generating powder is a dry substance, it is necessary to supply water for hydrating the substance that generates reaction heat by the mixed hydration reaction from the outside and mix it. When the body is in the state of a filter cake dehydrated sludge containing water, it is not necessary to supply water from the outside to mix. In this case, the water in the sludge is absorbed by the substance that undergoes the hydration reaction to generate a hydroxide, so that the water is simultaneously dried with the dust prevention treatment of the sludge.

Example Magnesium calcium carbonate powder (particle size: 0.6
mm sieve all through, 0.15 mm sieve 90% through) 1kg mortar mixer
And place it on the hammer crusher so that it is completely through the 2 mm sieve.
175g of crushed quick lime is mixed and mixed with resin while stirring
Aqueous PTFE suspension with 3% solid content (trade name: Teflon
25 g of 10 times diluted K20-J) and 60 g of water were added. After about 30 seconds
The quick lime hydrated and generated heat. Complete hydration reaction of quicklime
In order to do this, stop the mixer once and let it stand for 2 minutes.
The temperature of the compound reached 85 ° C. Stir for 10 seconds at this point
However, dust-free powder containing magnesium calcium carbonate as the main component
I got about 1.20 kg of body. This product is used for soil conditioners and fertilizers.
Materials, neutralizers, etc. are conceivable.

Example 2 Limestone washing water sludge with a water content of 16% (filter cake dehydration
Material, particle size 1.0 mm sieve residue 0.02%, 0.3 mm sieve residue 0.3%, 0.15 mm sieve
The remaining 5.5%) 1kg is taken into a mortar mixer and passed through a 2mm sieve.
Lightly baked dough crushed with a hammer crusher
260g romite (main component, 63% CaO, 33% MgO) and resin
Aqueous PTFE suspension with 3% form factor (trade name: Teflon K2
40-g of 10-fold diluted solution of 0-J was added and mixed for 1 minute. This mixture
When left still, the temperature reached 95 ° C after 3 minutes
After stirring for 30 seconds, it is dust-proof with PTFE fibrils
A fine powder of treated dehydrated sludge was obtained. In addition, processed products
Moisture attached is 0.1%, so drying and dustproofing can be done at once
It will be

Example 3 Granulated blast furnace slag (100 mesh sieve, which is dust-generating powder)
0) quicklime 0.
2 kg was added to obtain 1 kg of the mixture. Add this mixture to a volume of 2 l
Take it into a tal mixer and rotate the resin at 140 rpm
Aqueous PTFE suspension with 30% solid content (Trade name: Teflon
K20-J) 2g (PTFE 0.06% by weight to the mixture)
A solution dissolved in 0 ml was gradually added and stirred for 30 seconds. quicklime
The temperature was measured 2 minutes after the completion of the hydration reaction of
The temperature of the mixture had reached 90 ° C. 10 seconds at this point
No dust generated when treated with PTFE fibrils when stirred for a while
Thus, 1.06 kg of powdery powder was obtained. The uses of this thing are soil conditioners,
Fertilizer etc. can be considered.

C. EFFECTS OF THE INVENTION In order to perform dust-proof treatment of dust-generating powder with conventional PTFE fibrils, it is necessary to heat the dust-generating powder from the outside and stir at a temperature of about 80 to 200 ° C to apply compression-shear force. Yes,
Although heat energy and heating equipment were required, according to the method of the present invention, it is not necessary to heat from the outside, PTFE fibrils are easily produced only by a mixing operation, and dustproof treatment of dusting powder by fibrillated PTFE is possible. Done.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Teruo Urano 775-3 Ishizuka-cho, Sano City, Tochigi Prefecture (72) Inventor Hiroshi Miyaji 925-4 Nishikawada-cho, Utsunomiya City, Tochigi Prefecture (72) Masatsune Ogura Ichikawa City, Chiba Prefecture Arai 1-16-11 (72) Inventor Tetsuya Shimoda 1397-3 Hatsawa-cho, Hachioji-shi, Tokyo (72) Inventor Katsuaki Ishikawa 918-5 Shimoida-cho, Totsuka-ku, Yokohama-shi, Kanagawa (56) Reference JP-A-52 -31990 (JP, A) JP 49-107992 (JP, A) JP 47-38684 (JP, A) JP 60-191084 (JP, A)

Claims (1)

(57) [Claims] 1. A fibrillating polytetrafluoroethylene resin, a substance which generates reaction heat by a hydration reaction, and water are mixed and stirred with a dusting powder, and the temperature of the mixture is raised by the heat of the hydration reaction. A method for dust-proofing dust-producing powder, characterized in that the polytetrafluoroethylene resin is fibrillated by a compression-shear action during mixing and stirring, and the dust-producing powder is captured by the fibrils.