CN112313314A

CN112313314A - Antioxidant for coal and method for antioxidation of coal

Info

Publication number: CN112313314A
Application number: CN201980040595.4A
Authority: CN
Inventors: 宫原正树; 平野阳一; 吉川崇
Original assignee: Kurita Water Industries Ltd
Current assignee: Kurita Water Industries Ltd
Priority date: 2018-08-13
Filing date: 2019-04-11
Publication date: 2021-02-02
Also published as: PH12020552209A1; KR20210020140A; JP2020026489A; US20210292674A1; EP3800235A1; TW202020131A; EP3800235A4; WO2020035973A1

Abstract

Providing: an antioxidant agent which can further suppress the oxygen permeation into the inside of a coal deposit (coal hill) by coating the surface layer of the coal deposit. The present invention is an antioxidant for coal, which contains an oil-in-water droplet-type resin emulsion having emulsion particles with an average particle diameter of 0.3 [ mu ] m or more and 1.0 [ mu ] m or less. The antioxidant preferably further comprises a surfactant. The operator spreads the antioxidant over the coal deposit. This forms an anchor layer having a high oxygen permeation inhibiting effect on the surface of the coal deposit. Therefore, oxygen in the air atmosphere is prevented from penetrating into the coal deposit, and oxidation of the coal can be prevented.

Description

Antioxidant for coal and method for antioxidation of coal

Technical Field

The present invention relates to an antioxidant for coal and an antioxidant method for coal. More particularly, the present invention relates to a chemical agent and a method for preventing exothermic, thermal and spontaneous combustion associated with oxidation of coal accumulated in coal storage sites (yard, silos, etc.) of coal mines, iron works, power plants, etc.

Background

In iron works, power plants, and the like, coal is placed in a coal-placing place in a state where the coal is deposited. If the period of leaving the coal for a long time is long, carbon, sulfur, etc. contained in the coal react with oxygen in the air and undergo natural oxidation. The reaction heat generated during this natural oxidation is accumulated in the coal deposit as thermal energy, and the temperature in the coal deposit rises, resulting in spontaneous combustion.

Conventionally, in order to prevent such spontaneous heat generation and spontaneous combustion, there has been proposed a method of transferring and/or depositing coal while spreading a liquid containing SBR latex on the coal (see patent document 1). Further, it has been proposed to form a white coating film by spreading a resin solution containing white powder on the surface of a coal hill deposited outdoors (see patent document 2). Further, it has also been proposed to disperse an acrylic emulsion or a vinyl acetate emulsion on coal (see patent document 3).

Documents of the prior art

Patent document

Patent document 1: japanese patent No. 3948447

Patent document 2: japanese examined patent publication (Kokoku) No. 6-062974

Patent document 3: japanese examined patent publication No. 58-53037

Disclosure of Invention

Problems to be solved by the invention

There is still room for further improvement in the ability to suppress oxygen transmission into the interior of the coal deposit.

The present invention has been made in view of the above circumstances, and an object thereof is to provide: an antioxidant agent capable of further suppressing the oxygen permeability into the inside of a coal deposit (coal hill) by coating the surface layer of the coal deposit.

Means for solving the problems

The present inventors have found that the above problems can be solved by setting the average particle diameter of a resin emulsion dispersed in coal to a specific range, and have completed the present invention. 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 emulsion particles with an average particle diameter of 0.3 [ mu ] m or more and 1.0 [ mu ] m or less.

(2) The present invention also provides the antioxidant for coal according to (1), which further comprises a surfactant.

(3) The present invention also provides a method for preventing coal oxidation, wherein an antioxidant for coal, which contains an oil-in-water droplet-type resin emulsion having emulsion particles with an average particle diameter of 0.3 μm or more and 1.0 μm or less, is dispersed in a coal deposit.

(4) The present invention also provides the method for preventing coal oxidation according to item (3), wherein the antioxidant for coal is prepared by mixing the oil-in-water droplet-type resin emulsion and a surfactant.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, since the coal antioxidant contains the oil-in-water droplet-type resin emulsion in which the average particle diameter of the emulsion particles is within a specific range, if the coal antioxidant is scattered on the surface of the coal deposit, an anchor layer having a high oxygen permeation-inhibiting effect is formed on the surface of the coal deposit. Therefore, the permeation of oxygen in the air atmosphere into the coal deposit can be blocked, and the oxidation of coal can be prevented. Therefore, natural heat generation and spontaneous combustion due to the oxidation reaction can be effectively prevented as compared with the conventional ones. For this reason, accidents due to natural heat release and spontaneous combustion of coal are prevented in the bud, and the burden of various kinds of conservative management relating to these problems can be alleviated.

In particular, the antioxidant for coal preferably further contains a surfactant. By adding a surfactant to the coal deposit having high hydrophobicity, the permeability can be improved, and a coal fixing layer with spread chemical liquid and uniformity can be obtained. This further reduces the permeability of oxygen to the coal deposit, and further increases the oxidation prevention effect.

Drawings

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

Detailed Description

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 emulsion particles with an average particle diameter of 0.3 to 0.6 [ mu ] m. The antioxidant for coal preferably further contains a surfactant.

[ oil-in-water droplet-type resin emulsion ]

The type of the resin in the resin emulsion is not particularly limited, and preferably includes at least one selected from the group consisting of acrylic, methacrylic, and vinyl acetate. Among these, one or more of a butyl acrylate copolymer and a vinyl acetate/acrylic acid copolymer are more preferably contained. Also, it is preferable to include one or more of a butyl acrylate/methyl methacrylate copolymer, a vinyl acetate/butyl acetate/2-ethylhexyl acrylate copolymer, a butadiene/styrene/acrylic acid copolymer, a vinyl acetate/butyl acetate/2-ethylhexyl acrylate copolymer, and a vinyl acetate/acrylic ester 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, more preferably 0.5 μm or more. When the average particle diameter is too small, the desired oxidation preventing effect may not be obtained even if the antioxidant for coal is scattered on the surface of the coal deposit, which is not preferable.

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, still more preferably 0.7 μm or less, and particularly preferably 0.6 μm or less. If the average particle size is too large, the desired oxidation prevention effect may not be obtained even if the coal antioxidant is scattered on the surface of the coal deposit, which is not preferable.

In the present invention, the average particle diameter of the emulsion particles in the resin emulsion means an average diameter measured by using a laser analysis type particle size distribution measuring apparatus/Shimadzu SALD-7500nano (Shimadzu corporation).

The method for producing the resin emulsion is not particularly limited. For example, it can be easily prepared by emulsion polymerization of the monomer components. More specifically, it can be prepared by polymerizing monomer components in micelles formed in water with an emulsifier using a polymerization initiator.

[ surfactant ]

The antioxidant for coal preferably further contains a surfactant.

The type of the 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. This is considered to be because the surface of the coal deposit is hydrophobic, and therefore when a nonionic or cationic surfactant is used, the compatibility between the surface of the coal deposit and the resin emulsion is further improved, and as a result, a dense anchor layer is formed.

Examples of the anionic surfactant include sulfonic acid surfactants, and more specifically, di-2-ethylhexyl sulfosuccinate sodium salt surfactants. Examples of the cationic surfactant include ammonium salt surfactants, and more specifically, trialkyl benzyl ammonium salt surfactants.

Examples of the nonionic surfactant include ether surfactants, and more specifically, polyoxyalkylene alkyl ether surfactants. Examples of the amphoteric surfactant include betaine surfactants, and more specifically, fatty acid amide propyl betaine surfactants.

< Oxidation resistance method of coal >

In the method for preventing oxidation of coal according to the present embodiment, the resin emulsion is dispersed in a coal pile (coal hill). More preferably, the resin emulsion and the surfactant are mixed and dispersed in a coal deposit (coal hill).

In the present embodiment, the term "coal deposit" or "coal mountain" includes all deposited coals and is not necessarily a mountain-like deposit. In addition to deposits of coal deposited on a coal storage site, aggregates of coal such as coal charged into a container and deposited are all referred to as "coal deposits" or "coal mountains".

[ preparation of antioxidant for coal ]

In the present embodiment, the oil-in-water droplet-type resin emulsion may be used alone as the antioxidant for coal, or a mixture of the oil-in-water droplet-type resin emulsion and a surfactant may be used as the antioxidant for coal. When the oil-in-water droplet-type resin emulsion and the surfactant are mixed, the mixture obtained by mixing the oil-in-water droplet-type resin emulsion and the surfactant in advance may be brought to the site, or the oil-in-water droplet-type resin emulsion and the surfactant may be brought to the site separately and the respective materials may be mixed at the site.

The concentrations of the resin emulsion and the surfactant are not particularly limited, and the lower limit of the solid content concentration of the resin emulsion is preferably 0.005 wt% or more, more preferably 5 wt% or more, and further preferably 10 wt% or more, with respect to the coal antioxidant, as the concentration of the coal antioxidant used when the resin emulsion and the surfactant are dispersed in the coal deposit (coal hill). The upper limit of the solid content concentration of the resin emulsion is preferably 50 wt% or less, more preferably 40 wt% or less, and still more preferably 20 wt% or less with respect to the coal antioxidant.

The lower limit of the solid content concentration of the surfactant is preferably 0.005 wt% or more, more preferably 0.01 wt% or more, and still more preferably 0.1 wt% or more with respect to the coal antioxidant. The upper limit of the solid content concentration of the surfactant is preferably 50 wt% or less, more preferably 10 wt% or less, and still more preferably 1 wt% or less with respect to the coal antioxidant.

[ diffusion of antioxidant for coal ]

Next, the coal antioxidant is dispersed in the coal deposit (coal hill). As means for spreading, a spray gun, a sprinkler, or means for spreading from a hose of a stocker or a reclaimer, or the like may be used.

The amount of the antioxidant to be dispersed in the coal is not particularly limited, and is based on the coal deposit (coal hill) per 1m in consideration of both the effects of preventing spontaneous heat release and spontaneous combustion and the chemical cost²The surface area is preferably 10 to 1500g, particularly preferably 100 to 1000g, so that the amount of the active ingredient is 0.5 to 2000.

Examples

The present invention will be described in more detail with reference to examples.

< Experimental method >

Coal having a particle size of 2.0mm or less was deposited at a height of 5cm, and the deposit was made to have an effective content of 300g/m²About 2L of a 15% aqueous solution or aqueous dispersion of each chemical (antioxidant for coal) shown in Table 1 was scattered in a coal area to form a sample. Subsequently, the sample was left at room temperature for 1 week.

The sample after being left for 1 week was stored in the apparatus of the specification shown in fig. 1 so that the sample became a boundary wall separating 2 spaces. Next, as shown in fig. 1, the normal air was continuously blown to one space of the 2 spaces forming the boundary wall, and the pure nitrogen gas was continuously blown to the other space. At this time, the flow rates of the standard air and the pure nitrogen gas were both 30 mL/min, and the temperatures of the standard air and the pure nitrogen gas were both room temperature. Next, standard air and pure nitrogen gas were continuously blown for 4 hours, and then the oxygen concentration of the space on the nitrogen gas side was measured. The oxygen concentration was measured using an oxygen concentration meter 3600sn (manufactured by HACH ULTRA). Then, the oxygen concentration was 7.0% or less as "o", and the oxygen concentration exceeded 7.0% as "x". The results are shown in Table 1.

In the blank condition (comparative example 1), only water was dispersed in the coal.

[ Table 1]

In table 1, the various materials are as follows.

(A) Oil-in-water droplet type resin emulsion

The oil-in-water drop type resin emulsion is an emulsion of an acrylic copolymer.

(B) Surface active agent

The nonionic surfactant is a polyoxyalkylene alkyl ether surfactant.

The cationic surfactant is a trialkyl benzyl ammonium salt surfactant.

The anionic surfactant is a sodium di-2-ethylhexyl sulfosuccinate.

The amphoteric surfactant is a fatty acid amide propyl betaine surfactant.

< investigation >)

The permeation amount of oxygen through the coal deposit (coal mine) can be suppressed to 35% or more (examples 1 to 10) compared with the case where the average particle diameter of the emulsion particles in the oil-in-water droplet-type resin emulsion contained in the antioxidant for coal is 0.3 μm or 0.6 μm, or the case where the antioxidant for coal does not contain the resin emulsion (comparative example 1 where the liquid after dispersion is only water, or comparative example 6 where the antioxidant for coal is only water and a nonionic surfactant). From these results, it was found that the dilution liquid of the resin emulsion was dispersed on the surface of the coal being deposited, whereby the oxidation reaction of the coal could be suppressed, and as a result, the spontaneous heat generation could be suppressed and the period of the limit temperature causing spontaneous combustion could be extended. In addition, if the antioxidant for coal contains the resin emulsion, this effect can be obtained even if the surfactant is not contained (examples 1 and 6).

When the antioxidant for coal contains a surfactant in addition to the resin emulsion, the oxidation prevention effect is further improved (examples 2 to 5 and 7 to 10). Among them, when the surfactant is nonionic or cationic, the oxidation preventing effect is further increased (examples 2, 3, 7, and 8). This is considered to be because the surface of the coal deposit is hydrophobic, and therefore, when a nonionic or cationic surfactant is used, the compatibility between the surface of the coal deposit and the resin emulsion is further improved, and as a result, a dense anchor layer can be formed.

When the average particle diameter of the emulsion particles in the resin emulsion was 0.2 μm, a sufficient oxidation preventing effect could not be obtained even when the coal antioxidant contained a nonionic surfactant (comparative examples 2 and 3). This is presumably because the average particle size of the emulsion particles is too small, and an anchor layer is formed only in the upper part of the coal seam, and a uniform anchor layer cannot be formed.

On the other hand, when the average particle diameter of the emulsion particles in the resin emulsion was 1.4 μm or 2.8 μm, a sufficient oxidation preventing effect could not be obtained even when the coal antioxidant contained a nonionic surfactant (comparative examples 4 and 5). This is presumably because the average particle size of the emulsion particles is too large to penetrate the coal bed too much, and a dense anchor layer cannot be formed.

Claims

1. An antioxidant for coal, which comprises an oil-in-water droplet-type resin emulsion having emulsion particles with an average particle diameter of 0.3 to 1.0 [ mu ] m.

2. The antioxidant for coal as set forth in claim 1, further comprising a surfactant.

3. An antioxidant method for coal, wherein an antioxidant for coal comprising an oil-in-water droplet-type resin emulsion having emulsion particles with an average particle diameter of 0.3 μm or more and 1.0 μm or less is dispersed in a coal deposit.

4. The method for preventing oxidation of coal according to claim 3, wherein the antioxidant for coal is prepared by mixing the oil-in-water droplet-type resin emulsion and a surfactant.