TW202020131A - Coal anti-oxidation agent and coal oxidation prevention method - Google Patents

Abstract

Provided is an anti-oxidation agent that can be coated on the surface layer of a coal deposit (coal pile) to suppress further the amount of oxygen permeating to the interior of the deposit. This coal anti-oxidation agent contains an oil-in-water type resin emulsion, wherein the mean particle diameter of the emulsion particles is between 0.3 [mu]m and 1.0 [mu]m inclusive. Preferably, this anti-oxidation agent further contains a surfactant. An operator sprays the anti-oxidation agent over a coal deposit thereby forming a cemented layer with a high oxygen permeation suppressing effect on the coal deposit surface. Therefore, the oxygen in the atmospheric air is blocked from permeating to the interior of the coal deposit, enabling the prevention of coal oxidation.

Description

Antioxidant for coal and antioxidation method of coal

The invention relates to an antioxidant for coal and an anti-oxidation method of coal. In more detail, the present invention relates to a method for preventing coal that has been accumulated in coal yards (yards, silos, etc.) that have been accumulated in coal mines, ironworks, power plants, etc. Medicine and prevention method for heat generation, heat storage and spontaneous combustion accompanying oxidation.

In an iron plant or power plant, etc., coal is deposited in a state where it has been accumulated in a coal yard. When the standing period becomes a long period, the carbon or sulfur contained in the coal reacts with the oxygen in the air to perform natural oxidation. Furthermore, the reaction heat generated during this natural oxidation is accumulated as thermal energy inside the coal deposit, and the temperature inside the coal deposit rises and reaches spontaneous combustion.

Previously, in order to prevent such natural heating and spontaneous combustion, it was proposed to transfer and/or accumulate a solution containing Styrene Butadiene Rubber (SBR) latex on the side of coal when transferring and accumulating coal. (Refer to Patent Document 1). In addition, it has also been proposed to disperse a resin solution containing white powder on the surface of coal hills deposited outdoors to form a white coating film (see Patent Document 2). In addition, it has also been proposed to disperse acrylic emulsions or vinyl acetate emulsions on coal (see Patent Document 3). [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent No. 3948447 [Patent Document 2] Japanese Patent Publication No. 6-062974 [Patent Document 3] Japanese Patent Publication No. 58-53037

[Problems to be solved by the invention] However, there is room for further improvement regarding suppression of oxygen permeability into coal deposits.

The present invention has been made in view of the above actual circumstances, and its object is to provide an antioxidant that coats the surface layer of coal deposits (coal hills) and can further suppress the amount of oxygen permeation into the deposits . [Means to solve the problem]

The inventors of the present invention have found that by setting the average particle diameter of the resin emulsion dispersed in coal within a specific range, the above-mentioned problems can be solved, and the present invention has been completed. Specifically, the present invention provides the following.

(1) The present invention is an antioxidant for coal, which contains an oil-in-water droplet-type resin emulsion having an average particle diameter of emulsion particles of 0.3 μm or more and 1.0 μm or less.

(2) In addition, the present invention is the antioxidant for coal described in (1), which further contains a surfactant.

(3) In addition, the present invention is an anti-oxidation method for coal, which disperses coal antioxidants in coal deposits, the coal antioxidants containing emulsion particles having an average particle diameter of 0.3 μm or more and 1.0 μm or less in water Oil-drop resin emulsion.

(4) In addition, the present invention is the coal oxidation method described in (3), which mixes the oil-in-water resin emulsion with a surfactant to prepare the coal antioxidant. [Effect of invention]

According to the present invention, the antioxidant for coal contains an oil-in-water droplet type resin emulsion with an average particle size of emulsion particles in a specific range, so if the antioxidant for coal is spread on the surface of the coal deposit, it is formed on the surface of the coal deposit Consolidation layer with high oxygen permeability suppression effect. Therefore, the oxygen in the air environment is blocked from penetrating into the coal deposits, and the oxidation of the coal can be prevented. As a result, compared with the past, it is possible to effectively prevent natural heat and spontaneous combustion caused by the oxidation reaction. Therefore, accidents caused by natural heat generation and spontaneous combustion of coal can be prevented, and the burden of various maintenance and management related to these can be reduced.

In particular, the antioxidant for coal preferably further contains a surfactant. By adding surfactant to coal deposits with high hydrophobicity, permeability can be improved, and a uniform coal consolidation layer with chemical liquid expansion and uniformity can be obtained. As a result, the permeability of oxygen into the coal deposits is further reduced, and the antioxidant effect is further improved.

Hereinafter, embodiments of the present invention will be described, but the present invention is not particularly limited thereto.

<Antioxidant for coal> The antioxidant for coal of the present invention contains an oil-in-water droplet-type resin emulsion having an average particle diameter of emulsion particles of 0.3 μm or more and 1.0 μm or less. Furthermore, the antioxidant for coal preferably further contains a surfactant.

[Oil-drop resin emulsion in water] The type of resin in the resin emulsion is not particularly limited, but it is preferable to contain one or more kinds selected from acrylic, methacrylic, and vinyl acetate. Among them, it is more preferable to contain one or more kinds selected from butyl acrylate copolymer and vinyl acetate·acrylic acid copolymer. Furthermore, it is preferable to contain a copolymer selected from the group consisting of butyl acrylate·methyl methacrylate copolymer, vinyl acetate·butyl acetate·2-ethylhexyl acrylate copolymer, butadiene·styrene·acrylic acid copolymer, and acetic acid One or more of vinyl ester·butyl acetate·2-ethylhexyl acrylate copolymer and vinyl acetate·acrylate copolymer.

The lower limit of the average particle diameter of the emulsion particles in the resin emulsion is 0.3 μm or more. The lower limit of the average particle diameter is preferably 0.4 μm or more, and more preferably 0.5 μm or more. If the average particle size is too small, there is a possibility that even if the antioxidant for coal is spread on the surface of the coal deposit, the antioxidant effect corresponding to the expectation cannot be obtained, which is not good.

The upper limit of the average particle diameter of the emulsion particles in the resin emulsion is 1.0 μm or less. The upper limit of the average particle diameter is preferably 0.9 μm or less, more preferably 0.8 μm or less, further preferably 0.7 μm or less, and particularly preferably 0.6 μm or less. If the average particle size is too large, there is a possibility that even if the antioxidant for coal is spread on the surface of the coal deposit, the antioxidant effect corresponding to the expectation cannot be obtained, which is not good.

In the present invention, the average particle diameter of the emulsion particles in the resin emulsion refers to the average diameter measured by a laser analysis type particle size distribution measuring device/Shimadzu SALD-7500 nano (made by Shimadzu Corporation).

The production method of the resin emulsion is not particularly limited. For example, it can be easily prepared by subjecting monomer components to emulsion polymerization. More specifically, a polymerization initiator can be used to polymerize monomer components in micelles formed in water by an emulsifier, thereby preparing a resin emulsion.

[Surfactant] The antioxidant for coal preferably further contains a surfactant.

The type of surfactant is not particularly limited, and may be any of anionic, cationic, nonionic, and amphoteric surfactants. Among them, the surfactant is preferably nonionic or cationic, and particularly preferably nonionic. The reason for this may be because the surface of the coal deposit is hydrophobic, so when a nonionic or cationic surfactant is used, the compatibility of the surface of the coal deposit with the resin emulsion is further improved, and as a result, the formation Dense consolidation layer.

Examples of the anionic surfactants include sulfonic acid surfactants, and more specifically, sulfosuccinic acid di-2-ethylhexyl sodium salt surfactants. Examples of the cationic surfactants include ammonium salt surfactants, and more specifically, trialkylbenzyl ammonium salt surfactants.

Examples of the nonionic surfactants include ether surfactants, and more specifically, polyoxyalkylene alkyl ether surfactants. Examples of the amphoteric surfactants include betaine-based surfactants, and more specifically, fatty acid amidopropyl betaine-based surfactants.

<Antioxidation method of coal> In the coal anti-oxidation method of this embodiment, the resin emulsion is dispersed on a coal deposit (coal hill). More preferably, the resin emulsion and the surfactant are mixed and dispersed in a coal deposit (coal hill).

In the present embodiment, "coal deposits" or "coal mountains" are all coals that have been accumulated, and are not necessarily mountain-like accumulations. Except for the deposits of coal that have been accumulated in the coal yard, coal aggregates such as the coal that has been deposited in the container are collectively referred to as "coal deposits" or "coal hills."

[Preparation of antioxidants for coal] In this embodiment, the oil-in-water resin emulsion in water may be used alone as an antioxidant for coal, or a mixture of the oil-in-water resin emulsion in water and a surfactant may be used as an antioxidant in coal. When the oil-in-water resin emulsion and surfactant are mixed, the mixture of the oil-in-water resin emulsion and surfactant in advance can be brought to the site, and the oil-in-water resin emulsion and interface activity can also be brought to the site The agent is brought to the site individually and the materials are mixed at the site.

The concentration of the resin emulsion and surfactant is not particularly limited, but the concentration of the antioxidant for coal used when dispersed in the coal deposit (coal hill), the lower limit of the solid content concentration of the resin emulsion is relative to the antioxidant for coal, It is preferably 0.005% by weight or more, more preferably 5% by weight or more, and still more preferably 10% by weight or more. In addition, the upper limit of the solid content concentration of the resin emulsion is preferably 50% by weight or less, more preferably 40% by weight or less, and further preferably 20% by weight or less with respect to the coal antioxidant.

In addition, the lower limit of the solid content concentration of the surfactant is preferably 0.005% by weight or more, more preferably 0.01% by weight or more, and still more preferably 0.1% by weight or more with respect to the antioxidant for coal. In addition, the upper limit of the solid content concentration of the surfactant is preferably 50% by weight or less, more preferably 10% by weight or less, and further preferably 1% by weight or less with respect to the antioxidant for coal.

[Dispersion of antioxidants for coal] Then, the coal was dispersed with antioxidants on the coal deposits (coal mountains). As a method of dispersing, a method such as spraying by a raingun or a sprinkler, or a hose from a stacker or a reclaimer can be used.

The amount of anti-oxidant for coal is not particularly limited, but considering both the effects of natural heat generation and spontaneous combustion and the cost of chemicals, as a basis, as long as it is effective per 1 m ² of the surface area of coal deposits (coal hills) The amount of ingredients should be 0.5 g to 2,000 g, preferably 10 g to 1,500 g, and particularly preferably 100 g to 1,000 g. [Example]

The following examples illustrate the present invention in more detail.

<Experimental method> After stacking coal with a particle size of 2.0 mm or less to a height of 5 cm, the effective component becomes 300 g/m ² -coal area, and approximately 2 L of each of the deposits shown in Table 1 is dispersed on the deposit A 15% strength aqueous solution or dispersion of a chemical (antioxidant for coal) is made into a test piece. Furthermore, the test piece was left at room temperature for 1 week.

The test piece after one week of storage was accommodated in a device shown in FIG. 1 so that the test piece became a boundary wall separating two spaces. Furthermore, as shown in FIG. 1, the standard air is continuously sent to one of the two spaces as the boundary wall, and the pure nitrogen gas is continuously sent to the other space. At this time, the flow rate of standard air and pure nitrogen is 30 mL/min, and the temperature of standard air and pure nitrogen is room temperature. Furthermore, after continuous delivery of standard air and pure nitrogen for 4 hours, the oxygen concentration in the space on the nitrogen side was measured. Oxygen concentration meter 3600sn (made by Hach Ultra) was used for measurement of oxygen concentration. In addition, the case where the oxygen concentration is 7.0% or less is set to “○”, and the case where the oxygen concentration exceeds 7.0% is set to “×”. The results are shown in Table 1.

Furthermore, in the blank condition (Comparative Example 1), only water was dispersed on coal.

[Table 1]

In Table 1, various materials are shown below. (A) Oil-drop resin emulsion in water The oil-drop resin emulsion in water is an emulsion of acrylic copolymer. (B) Surfactant The nonionic surfactant is a polyoxyalkylene alkyl ether surfactant. The cationic surfactant is a trialkylbenzyl ammonium salt surfactant. The anionic surfactant is a surfactant of sodium salt of di-2-ethylhexyl sulfosuccinate. Amphoteric surfactants are fatty acid amidopropyl betaine based surfactants.

＜Inspection＞ When the average particle size of the emulsion particles in the oil-in-water resin emulsion contained in the coal antioxidant is 0.3 μm or 0.6 μm, and the coal antioxidant does not contain the resin emulsion (the dispersion is only water Comparative Example 1, or the coal-based antioxidant is only water and the non-ionic surfactant Comparative Example 6), can inhibit more than 35% of the amount of oxygen permeating through the coal deposit (coal mountain) (Example 1 to Example 10). From this result, it can be said that by spreading the dilution liquid of the resin emulsion on the coal surface in accumulation, the oxidation reaction of the coal can be suppressed, and as a result, the natural heat generation can be suppressed and the period of reaching the limit temperature of spontaneous combustion can be delayed. In addition, as long as the antioxidant for coal contains a resin emulsion, even if it does not contain a surfactant, the above-mentioned effect can be obtained (Example 1 and Example 6).

When the antioxidant for coal contains a surfactant other than the resin emulsion, the antioxidant effect is further improved (Example 2 to Example 5, Example 7 to Example 10). Among them, when the surfactant is nonionic or cationic, the antioxidant effect is further improved (Example 2, Example 3, Example 7, Example 8). The reason for this may be because the surface of the coal deposit is hydrophobic, so when a nonionic or cationic surfactant is used, the compatibility of the surface of the coal deposit with the resin emulsion is further improved, and as a result, the formation Dense consolidation layer.

When the average particle diameter of the emulsion particles in the resin emulsion is 0.2 μm, even if the antioxidant for coal contains a nonionic surfactant, a sufficient antioxidant effect cannot be obtained (Comparative Examples 2 and 3). It is presumed that the reason is that the average particle size of the emulsion particles is too small, and only a consolidated layer is formed on the upper part of the coal layer, and a uniform consolidated layer cannot be formed.

On the other hand, when the average particle diameter of the emulsion particles in the resin emulsion is 1.4 μm or 2.8 μm, even if the antioxidant for coal contains a nonionic surfactant, a sufficient antioxidant effect cannot be obtained (Comparative Example 4 and Comparative Example 5). It is speculated that the reason is that the average particle size of the emulsion particles is too large and excessively penetrates into the coal layer, so that a dense consolidation layer cannot be formed.

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FIG. 1 is a schematic diagram of a test apparatus used in a test using the antioxidant for coal of the present invention.

Claims (4)

An antioxidant for coal includes an oil droplet type resin emulsion in water having an average particle size of emulsion particles of 0.3 μm or more and 1.0 μm or less. The antioxidant for coal as described in item 1 of the scope of the patent application further includes a surfactant. An anti-oxidation method for coal, which disperses an antioxidant for coal on a coal deposit, the antioxidant for coal includes an oil droplet type resin emulsion in water having an average particle size of emulsion particles of 0.3 μm or more and 1.0 μm or less. An anti-oxidation method for coal as described in item 3 of the scope of the patent application, which mixes the oil-in-water resin emulsion with a surfactant to prepare the anti-oxidant for coal.

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