JPS6248B2 - - Google Patents

Description

Detailed Description of the Invention This invention is a method of waterproofing deposits by coating the surface of the deposits when coal, coke, iron ore, minerals such as river sand, wood powder, etc. are deposited in open piles over a long period of time. , relates to a coating method for dustproofing, preventing oxidation due to air, etc.

Generally, coal, coke, wood powder, etc. are often stored in open piles at steel mills, gas plants, paper mills, etc. However, during storage, these sediments are easily stirred up by the wind, causing dust pollution in surrounding areas and causing sediment loss, and during rainfall, they flow into rivers and the sea, causing sewage. In addition, if the water content in deposits such as coal, coke, or iron ore becomes excessive, there are disadvantages such as evaporative heat loss of water when burning the deposits.

An excellent way to solve these problems is to
A method has already been proposed in which a water-insoluble coating film is formed after drying by coating the surface of the deposit with a paint containing the same or similar powder as the deposit as a filler.

In this method, the paint contains a large amount of filler, is highly viscous, and has thixotropic properties, and it dries and solidifies while remaining on the surface layer without penetrating into the deposit, resulting in waterproof, dustproof, etc. Forms a coating film. Here, since the surface of the deposit has large irregularities and changes in density, a large amount of coating is required to form a continuous film thereon, and the average coating thickness after drying usually reaches 5 mm or more.

For this reason, the paint cost per unit volume increases, and the running cost of painting also increases due to the high viscosity. In addition, due to the large thickness of the film, it takes two days to dry and solidify in the summer and more than four days in the winter.
If it rained during this period, the performance of the paint film would be significantly impaired, so there were restrictions such as the installation schedule having to be chosen according to the weather.

On the other hand, the inventors discovered that the waterproof and dustproof properties of the above-mentioned coating film are substantially achieved only by a thin film on the very surface of the coating film, but in reality, it is necessary to reduce the amount of coating. When the coating film is made thinner, a continuous coating cannot be formed, and thick coatings with the above-mentioned drawbacks are unavoidable.

As a result of intensive research to solve these problems, the inventors found that when the viscosity of the paint was adjusted to a specific low viscosity range and the amount of paint was limited to a specific range, deposits on the surface The fine sediment particles in the layer flow moderately and settle down to the sparse parts of the sediment surface, creating a so-called clogging effect, which results in the formation of an extremely thin continuous film on the sediment surface. They discovered that this is the case and came up with this invention.

That is, when applying a coating paint containing a solute that becomes water-insoluble after drying to the surface of field deposits, the present invention adjusts the viscosity of the paint to 5 to 500 centipoise, and adjusts the coating amount to 1 to 5 kg/ ^m2. The present invention relates to a method for covering open deposits, characterized in that the method is set as follows.

The open deposits applied to this invention are, for example, coal (powder), coke (powder), iron ore, minerals such as river sand, copper ore, limestone, bauxite and other metal ores, or organic powders such as wood powder. etc.

In this invention, the coating material contains a solute that becomes water-insoluble after drying, and is preferably a water emulsion type, but an organic solvent type may also be used. In the case of a water emulsion paint, optional components such as a film-forming agent, a thickener, an antifoaming agent, and a freeze-thaw stabilizer can be added. In particular, the thickener is important for adjusting the viscosity described below, and its selection must be carefully considered.

Typical examples of resins that are the main component of paint solids include vinyl acetate polymers or their copolymers, acrylic acid ester, methacrylic acid ester polymers, or their copolymers with styrene in water emulsion systems. , copolymers of butadiene and styrene, copolymers of butadiene and acrylonitrile, and organic solvent-based alkyds such as styrenated alkyds, xylene resin-modified alkyds, and copolymers of vinyl chloride and vinyl acetate.

Specific examples of film forming aids and thickeners that are usually added to water emulsion paints include butyl cellosolve, butyl carbitol, butyl cellosolve acetate, carbitol acetate, and hexylene glycol. , dibutyl phthalate, dioctyl phthalate, etc.
Thickeners include methylcellulose, ethylcellulose, polyvinyl alcohol, hydroxyethylcellulose, carboxymethylcellulose, sodium polyacrylate, casein, and starch.

In this invention, when applying the above-mentioned paint to the surface of open deposits, the viscosity is adjusted to 5 to 500 centipoise, preferably 10 to 100 centipoise, and the coating amount is 1 to 5 kg/m ² , preferably 2. It is particularly important to set it to ~3Kg/ ^m2 . When this condition is met and the coating is applied, an extremely thin uniform continuous film is formed on the surface layer of the field deposit, and the film has sufficient waterproof, dustproof, and antioxidant properties.

This effect is thought to be due to the following mechanism. In the surface layer of a deposit coated with paint, large sediment particles in the surface layer do not move, but fine particles flow along with the flow of the paint, floating on the sediment surface and spreading to sparse areas of the surface layer. When reaching a point (where large sediment particles gather), the paint stagnates and the fine particles settle. As a result, the surface layer becomes clogged and the entire surface becomes a dense layer. Since the paint maintains an appropriate viscosity, it does not easily penetrate into the deposit, but the clogging effect of the fine particles mentioned above makes it even more difficult for it to penetrate inside, and it remains stuck on the surface layer. Dry and solidify. For this reason, deposits originally have an extremely sparse surface layer, and even though paint has an extremely low viscosity, the paint remains in the surface layer without penetrating into the interior, making it extremely efficient. Forms a continuous coating.

When the viscosity of the paint is less than 5 centipoise, the paint penetrates quickly into the deposit and does not lead to particulate flow and therefore no plugging effect. Moreover, if the particle diameter exceeds 500 centipoise, the flow of fine particles is suppressed by viscosity, so that no clogging effect is produced. If the amount of coating is less than 1 kg/m ² , sufficient fluidity will not be created to float and move sediment particles, and if it exceeds 5 kg/m ² , the surface layer of the sediment will be saturated with paint, causing landslides and landslides. Put it away.

Based on this mechanism, it is expected that by mixing a filler into the coating paint in advance, the fluidity of the filler will produce the same plugging effect as described above during coating. In fact, the use of such fillers gives favorable results, such as when the surface layer of the deposit is low in particulates. However, in this case, the viscosity of the paint increases, so the viscosity must be lowered by dilution. However, care must be taken because this method has disadvantages such as sedimentation of the filler along with a decrease in viscosity. Furthermore, some fillers are undesirable if mixed into the deposit, and it is generally desirable to use a material that is the same as or similar to the deposit.

In the present invention, spray coating, flow coating, or other methods can be used as the coating method, and after this coating, it is usually sufficient to allow the coating to dry naturally. During this time, the applied paint stays on the surface without penetrating into the interior due to the packing effect, so it dries quickly and forms a uniform and continuous film.

As detailed above, according to the present invention, since the paint used has a low viscosity, the running cost of the coating can be reduced, and since the film thickness is thin, the paint cost per unit area can be reduced. Furthermore, since the time required for drying and solidification can be shortened, there are advantages such as the fact that the application process is not so dependent on the weather.

Next, embodiments of this invention will be described.

Example 1 50% by weight water emulsion 100 of a copolymer of butyl acrylate and styrene with a monomer composition of 65:35
Part by volume, 2% by weight aqueous solution of sodium polyacrylate
12 parts by volume of butyl cellosolve, 2 parts by volume of butyl cellosolve, and 0.8 parts by volume of a 10% by weight aqueous solution of sodium hexametaphosphate were added with 885 parts by volume of water to prepare a coating material with a viscosity of 20 centipoise.

Using this paint, the surface of an open pile of coal powder with a floor area of 4000 m ² and a height of 15 m was sprayed at a target of 3 kg/m ² . The coating film was almost dry and solidified after 5 hours. The film thickness was approximately 0.5 mm.

The deposit coated in this manner did not disintegrate even after 6 months had passed, and no scattering or runoff of coal powder or infiltration of rainwater was observed.

Example 2 100 parts by volume of 48% by weight latex of a copolymer of styrene and butadiene with a monomer composition of 50:50, 3 parts by volume of cellosolve acetate, 2 parts by volume of methyl cellulose
225 parts by volume of water was added to 25 parts by volume of a wt% aqueous solution and 100 parts by weight of river sand of 10 mesh passes to prepare a coating paint having a viscosity of 60 centipoise and a solid content concentration of 33 wt%.

This paint was poured at 2 kg/m ² onto the surface of an open pile of river sand with a floor area of 240 m ² and a height of 6 m. The coating film was almost dry and solidified after 8 hours. The film thickness was approximately 1.5 mm.

The deposit coated in this manner did not disintegrate even after 6 months had passed, and no scattering, runoff, or infiltration of rainwater was observed.

Comparative Example A coating paint having a viscosity of 600 centipoise was prepared, having the same composition as in Example 1 except that the amount of water was 300 parts by volume. Using this paint, spray painting was performed on the surface of the same deposit as in Example 1 at a target of 4 kg/m ² . The coating film dried and solidified after 3 days. The film thickness was approximately 4 mm.

After three months, cracks began to appear in the coated deposits coated with this method, and an increase in moisture content was observed.

Claims (1)

[Claims] 1. When coating the surface of open deposits with a coating paint containing a solute that becomes water-insoluble after drying, the viscosity of the paint was adjusted to 5 to 500 centipoise, and the coating amount was set to 1 to 5 kg/ ^m2. A method for covering open deposits, characterized by: