Method for stacking bulk material

Abstract

To provide a method for piling up bulk materials by which a pile of the bulk materials in a yard hardly collapses even in heavy rain, an increase in water content can be suppressed, and the bulk materials hardly adhere to a conveying device when the bulk materials are taken out from the pile and conveyed.SOLUTION: The method for piling bulk materials in a yard includes mixing a polymer flocculant with the bulk materials before being piled in the yard. The method for piling up the bulk materials includes piling up a mixture containing the bulk materials and the polymer flocculant in the yard and spraying a coating agent on the surface of the mixture piled up in the yard.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for piling bulk materials. [Background technology]

[0002] In steelworks, power plants, and the like, bulk materials such as coal, ore, limestone, and coke, which are used as raw materials for steelmaking or fuel for power generation, are generally transported by a transport device such as a conveyor and piled up in an outdoor storage area called a yard by a stacker or the like, where they are stored for a certain period of time until use. When the bulk materials are to be used, a certain amount of the bulk materials is dispensed from the pile in the yard by a reclaimer or the like onto a transport device such as a conveyor and transported to the next process.

[0003] Bulk materials piled up in yards can encounter problems such as dust generation due to wind, and the collapse of piles and the flow of bulk materials due to rainfall. In particular, the increase in moisture content of bulk materials due to rainwater seeping into piled bulk materials not only makes them more susceptible to the aforementioned collapse and flow, but also consumes extra energy to evaporate the moisture in subsequent processes such as combustion when the bulk materials are used as raw materials for steelmaking or fuel for power generation. This not only results in economic losses but also creates inconvenience in terms of environmental measures due to increased carbon dioxide emissions.

[0004] In view of the above-mentioned problems, various techniques have been proposed to suppress dust, landslides, and the like. For example, Patent Document 1 discloses an invention relating to a method for piling raw materials for ironmaking, which includes a step of adding a dilute liquid containing 0.1 to 2 mass% of a polymer flocculant as an active ingredient to at least one of the raw materials before being piled in a raw material yard and the raw materials after being piled. Furthermore, Patent Document 2 discloses an invention relating to a surface treatment agent for piled coal or petroleum coke, which comprises: Component A: 30 to 95 mass% of an asphalt emulsion containing 30 to 70 mass% of asphalt, 0.5 to 10 mass% of a surfactant, and 20 to 69.5 mass% of water; and Component B: 5 to 70 mass% of a high-concentration resin emulsion containing 30 to 70 mass% of a resin component.

[0005] Furthermore, Patent Document 3 discloses an invention relating to a surface coating method for piled coal, in which a coal pile containing 50-70% fine coal particles of 3 mm or less is coated with a coating composition in which the surfactant content in the water-repellent coating agent is adjusted to 0.005-0.05%. Patent Document 4 discloses an invention relating to a spray composition comprising an emulsion copolymer emulsion having predetermined monomers such as acrylic acid ester monomers and unsaturated carboxylic acid monomers as constituent units, a surfactant, and a zirconium compound. Patent Document 5 discloses an invention relating to a treatment method for piled coal piles, in which a predetermined amount of SBR emulsion is sprayed onto the pile, and after drying, a predetermined amount of acrylic emulsion is sprayed to form a resin protective film on the surface of the pile. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2020-040833 [Patent Document 2] Japanese Patent Application Laid-Open No. 2002-020769 [Patent Document 3] Japanese Patent Application Publication No. 10-259390 [Patent Document 4] Japanese Patent Application Publication No. 63-071009 [Patent Document 5] Japanese Patent Publication No. 146804 / 1983 Summary of the Invention [Problem to be solved by the invention]

[0007] In recent years, an increase in the frequency of heavy rainfall due to the progress of global warming has been predicted worldwide, and even in Japan, the frequency of heavy rainfall events with daily precipitation of 200 mm, hourly precipitation of 30 mm, or even 50 mm or more is on the rise. During such heavy rainfall, steelworks may not be able to adequately respond even with the above-mentioned conventional techniques. Specifically, during heavy rainfall, problems may arise, such as an increase in the moisture content of bulk materials in piles in yards, or the flow of bulk materials from piles or the collapse of piles, resulting in the burial of collapsed bulk materials on running rails of stackers and conveyors and other transport devices.

[0008] Furthermore, after rainfall, when bulk materials are removed from piles in yards by reclaimers or the like and transported by conveying equipment, the loose materials may become wet and easily adhere to the conveying equipment, which can result in bulk material loss or clogging of the conveying equipment.

[0009] Therefore, the present invention aims to provide a method for piling bulk materials in a yard that is less likely to collapse even during heavy rain, that can suppress an increase in moisture content, and that prevents the bulk materials from adhering to the transport device when they are removed from the pile and transported. [Means for solving the problem]

[0010] The present invention provides a method for piling bulk materials in a yard, the method comprising: mixing a polymer flocculant with the bulk materials before they are piled in the yard; piling a mixture containing the bulk materials and the polymer flocculant in the yard; and spraying a coating agent on the surface of the mixture piled in the yard. [Effects of the Invention]

[0011] According to the present invention, a method for piling bulk materials can be provided that makes it difficult for piles in a yard to collapse even during heavy rain, can suppress an increase in moisture content, and makes it difficult for the bulk materials to adhere to the transport device when removing them from the pile and transporting them. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic perspective view of a plastic mold used in a test to confirm the effect of suppressing the collapse of a pile of coal under conditions simulating heavy rain in Examples and Comparative Examples. [Figure 2] FIG. 10 is a schematic explanatory diagram of a test to confirm the effect of suppressing adhesion of coal to a transport device when removing and transporting coal from a pile after water sprinkling, simulating heavy rain, in Examples and Comparative Examples. [Figure 3] FIG. 1 is a schematic perspective view of an inclined cylindrical container used in a test to confirm the effect of suppressing an increase in the moisture content of coal inside a pile after heavy rain in Examples and Comparative Examples. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments.

[0014] A method for piling bulk materials (hereinafter, sometimes referred to as "this method") according to one embodiment of the present invention relates to a method for piling bulk materials in a yard. This method includes mixing a polymer flocculant with the bulk materials before they are piled in the yard, piling the mixture containing the bulk materials and the polymer flocculant in the yard, and spraying a coating agent on the surface of the mixture piled in the yard.

[0015] According to this method having the above configuration, piles in the yard are less likely to collapse even during heavy rain, and an increase in moisture content can be suppressed. Furthermore, when bulk materials are removed from the piles and transported, they are less likely to adhere to the transport device. Therefore, for example, in steelworks, it is possible to prevent the transport device, such as the running rails of a stacker or a conveyor, from becoming buried in collapsed bulk materials. Furthermore, it is possible to prevent the loss of bulk materials due to the adhesion of bulk materials to the transport device and the clogging of the transport device.

[0016] Furthermore, piles in the yard may be subjected to various vibrations, such as indirect vibrations from transport equipment near the yard and direct vibrations to the pile when only a portion of the pile is transported. In one aspect of this method, a coating film can be formed on the pile of a mixture containing loose material and a polymer flocculant piled in the yard, thereby providing vibration resistance that makes the pile less likely to crack or collapse even when the vibration occurs. Furthermore, by adopting a preferred configuration for the coating agent described below, it is also expected to have the effect of suppressing cracks and tears in the coating due to the vibration.

[0017] Furthermore, in yards, rainfall can cause loose materials such as powdered iron ore and coal in piles to flow into stormwater as suspended matter, and stormwater drainage containing such suspended matter is usually channeled into dedicated treatment facilities, treated by adding chemicals or leaving the water to stand, and then discharged into public waters. In one aspect of this method, powdered loose materials are more likely to be entrained in large volumes of rainwater caused by heavy rain in yards and flow out as fine suspended matter, and the effect of suppressing the outflow of suspended matter can be expected to reduce the load on the treatment facilities.

[0018] This method involves mixing a polymer flocculant with bulk materials before they are piled up in a yard. The yard in this method is an outdoor bulk material storage, preservation, or depository. Examples of yard locations include steelworks, power plants (e.g., thermal power plants), mines, and mining sites. Among these, at least one selected from the group consisting of steelworks and power plants is preferred, and steelworks is more preferred.

[0019] The term "loose" is used to refer to cargo that is transported in an unpackaged state. Examples of loose materials in this method include coal, iron ore, limestone, coke, steelmaking dust, sand, and gravel. Among these, at least one selected from the group consisting of coal and iron ore is preferred, and coal is more preferred. Because this method provides greater technical significance, coal with a proportion of coal with a particle size of 5 mm or less determined by a sieving method of 10% by mass or more is even more preferred.

[0020] Before being piled up in a yard, bulk materials such as coal and iron ore may come into contact with water, for example, due to rainfall or sprinkling of water to prevent dust, at the bulk material mining site, in storage facilities inside and outside the mining site, on conveying devices such as belt conveyors, and on transport equipment such as trucks and ships. Therefore, the bulk materials before being piled up in a yard may contain water. The moisture content of the bulk materials before being mixed with the polymer flocculant is not particularly limited, but is preferably 0 to 50% by mass, more preferably 1 to 30% by mass, and even more preferably 5 to 20% by mass, based on the total mass of the bulk materials in a water-containing state (hydrated bulk materials). In the present disclosure, the moisture content of the bulk materials is the percentage (% by mass) calculated by dividing the mass of water in the bulk materials by the total mass of the bulk materials.

[0021] A polymer flocculant is a polymer compound that functions as a flocculant, and is thought to form flocculants by generating an adsorption-crosslinking action through electrostatic interactions, hydrogen bonds, etc. As the polymer flocculant, a water-soluble or water-swellable polymer (including copolymers) that functions as a flocculant is preferably used, and a water-soluble polymer (including copolymers) is more preferably used. The polymer flocculant can contain, as a constituent unit derived from a polymerizable monomer, any of an anionic constituent unit derived from an anionic monomer, a cationic constituent unit derived from a cationic monomer, and a nonionic constituent unit derived from a nonionic monomer, and can contain one or more of these.

[0022] The polymer flocculant may be an anionic polymer flocculant, a cationic polymer flocculant, a nonionic polymer flocculant, or an amphoteric polymer flocculant. One of these may be used alone, or two or more may be used in combination.

[0023] In this disclosure, a polymer flocculant having both anionic constituent units and cationic constituent units is referred to as an amphoteric polymer flocculant. Furthermore, among polymer flocculants other than amphoteric polymer flocculants, a polymer flocculant having an anionic constituent unit and a colloid equivalent value (meq / g) of -1.1 meq / g or less is referred to as an anionic polymer flocculant. Similarly, a polymer flocculant having a cationic constituent unit and a colloid equivalent value (meq / g) of 0.1 meq / g or more is referred to as a cationic polymer flocculant. Furthermore, in this disclosure, a polymer flocculant having a colloid equivalent value (meq / g) of -1.0 to 0.0 meq / g is referred to as a nonionic polymer flocculant.

[0024] In this disclosure, the colloid equivalent value (meq / g) per 1 g of polymer flocculant is measured and calculated by colloid titration using a polymer flocculant aqueous solution as the test solution, a polyvinyl potassium sulfate solution as the standard polyanion as the titrant, and a polydiallyldimethylammonium chloride solution or a methyl glycol chitosan solution as the standard polycation. The pH of the test solution can be adjusted to an appropriate range depending on the ionicity of the polymer flocculant being measured (e.g., approximately pH 4 for cationic polymer flocculants, approximately pH 7-11 for nonionic and anionic polymer flocculants). Examples of indicators that can be used include toluidine blue. More specifically, the colloid equivalent value can be measured and calculated by the colloid titration method described in the examples below. The colloid titration method described in the examples below is based on the test method described in "Sewage Testing Methods, Vol. 1, 2012 Edition," pp. 737-742, published by the Japan Sewage Works Association.

[0025] Examples of anionic polymer flocculants include homopolymers of anionic monomers, copolymers of two or more anionic monomers, and copolymers of anionic monomers and nonionic monomers copolymerizable with the anionic monomers. These may be used alone or in combination of two or more.

[0026] Examples of cationic polymer flocculants include homopolymers of cationic monomers, copolymers of two or more types of cationic monomers, and copolymers of cationic monomers and nonionic monomers copolymerizable with the cationic monomers. These may be used alone or in combination of two or more.

[0027] Examples of nonionic polymer flocculants include homopolymers of nonionic monomers, copolymers of two or more nonionic monomers, and copolymers of a nonionic monomer as the main component and an ionic (anionic or cationic) monomer copolymerizable with the nonionic monomer. These may be used alone or in combination of two or more.

[0028] Examples of amphoteric polymer flocculants include copolymers of cationic monomers and anionic monomers, and copolymers of cationic monomers, anionic monomers, and nonionic monomers. These may be used alone or in combination of two or more.

[0029] Examples of anionic monomers include (meth)acrylic acid, itaconic acid, maleic acid, vinyl sulfonic acid, vinylbenzenesulfonic acid, allylsulfonic acid, styrenesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, and salts thereof. Examples of salts include alkali metal salts and ammonium salts. Examples of alkali metal salts include sodium salts and potassium salts. One type of anionic monomer may be used alone, or two or more types may be used in combination. Among the anionic monomers, (meth)acrylic acid and salts thereof are preferred, and (meth)acrylic acid, alkali metal salts, and ammonium salts thereof are more preferred.

[0030] In the present disclosure, the term "(meth)acrylic acid" includes both "acrylic acid" and "methacrylic acid," the term "(meth)acrylate" includes both "acrylate" and "methacrylate," and the term "(meth)acrylamide" includes both "acrylamide" and "methacrylamide."

[0031] Examples of cationic monomers include dialkylaminoalkyl(meth)acrylates, dialkylaminoalkyl(meth)acrylamides, and their neutralized salts (neutralized salts with acids such as hydrochloric acid or sulfuric acid) and quaternary ammonium salts (quaternized products). Examples of dialkylaminoalkyl(meth)acrylates include 2-(dimethylamino)ethyl(meth)acrylate, 2-(diethylamino)ethyl(meth)acrylate, and 2-(dimethylamino)propyl(meth)acrylate. Examples of dialkylaminoalkyl(meth)acrylamides include N-[2-(dimethylamino)ethyl](meth)acrylamide, N-[3-(dimethylamino)propyl](meth)acrylamide, and N-[2-(diethylamino)ethyl](meth)acrylamide. Examples of dialkylaminoalkyl(meth)acrylate quaternary ammonium salts include reaction products of dialkylaminoalkyl(meth)acrylates with quaternizing agents. Examples of dialkylaminoalkyl(meth)acrylamide quaternary ammonium salts include reaction products of dialkylaminoalkyl(meth)acrylamides with quaternizing agents, etc. Examples of quaternizing agents include methyl chloride, ethyl chloride, benzyl chloride, methyl bromide, ethyl bromide, benzyl bromide, methyl iodide, and ethyl iodide.

[0032] The cationic monomer may be used alone or in combination of two or more. Among the cationic monomers, dialkylaminoalkyl(meth)acrylate quaternary ammonium salts are preferred. Specific examples thereof include dimethylaminoethyl(meth)acrylate methyl chloride quaternary salt, dimethylaminoethyl(meth)acrylate benzyl chloride quaternary salt, dimethylaminoethyl(meth)acrylate methyl sulfate quaternary salt, dimethylaminoethyl(meth)acrylate hydrochloride, and dimethylaminoethyl(meth)acrylate sulfate. Among these, at least one selected from the group consisting of dimethylaminoethyl acrylate methyl chloride quaternary salt (also known as [2-(acryloyloxy)ethyl]trimethylammonium chloride), dimethylaminoethyl methacrylate methyl chloride quaternary salt (also known as [2-(methacryloyloxy)ethyl]trimethylammonium chloride), and dimethylaminoethyl acrylate benzyl chloride quaternary salt (also known as [2-(acryloyloxy)ethyl]benzyldimethylammonium chloride) is more preferred.

[0033] Examples of nonionic monomers include (meth)acrylamide, N-methyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, acrylonitrile, methacrylonitrile, styrene, vinyl acetate, alkyl(meth)acrylates, and hydroxyalkyl(meth)acrylates. Examples of alkyl(meth)acrylates include methyl(meth)acrylate, ethyl(meth)acrylate, propyl(meth)acrylate, butyl(meth)acrylate, and 2-ethylhexyl(meth)acrylate. Examples of hydroxyalkyl(meth)acrylates include 2-hydroxyethyl(meth)acrylate, hydroxypropyl(meth)acrylate, and 4-hydroxybutyl(meth)acrylate. One type of nonionic monomer may be used alone, or two or more types may be used in combination. Among nonionic monomers, (meth)acrylamide is preferred.

[0034] As anionic polymer flocculants, poly(meth)acrylic acid-based polymer flocculants having structural units derived from at least one selected from the group consisting of (meth)acrylic acid and its salts (hereinafter also referred to as "(meth)acrylic acid-based monomers"), and polymer flocculants of (meth)acrylamide-(meth)acrylic acid-based copolymers having structural units derived from at least one selected from (meth)acrylamide and structural units derived from the (meth)acrylic acid-based monomers are more preferred. Among these, polymer flocculants of (meth)acrylamide-(meth)acrylic acid-based copolymers are even more preferred. In the present disclosure, the term "at least one selected from the group consisting of (meth)acrylic acid and its salts" is synonymous with "at least one selected from the group consisting of acrylic acid, methacrylic acid, and salts thereof." Furthermore, the term "at least one selected from (meth)acrylamides" is synonymous with "at least one selected from the group consisting of acrylamide and methacrylamide."

[0035] As the cationic polymer flocculant, polydialkylaminoalkyl(meth)acrylate quaternary ammonium salt-based polymer flocculants having structural units derived from at least one selected from the above-mentioned dialkylaminoalkyl(meth)acrylate quaternary ammonium salts, and (meth)acrylamide-dialkylaminoalkyl(meth)acrylate quaternary ammonium salt copolymer-based polymer flocculants having structural units derived from at least one selected from (meth)acrylamide are more preferred. Among these, (meth)acrylamide-dialkylaminoalkyl(meth)acrylate quaternary ammonium salt copolymer-based polymer flocculants are even more preferred.

[0036] Furthermore, as the nonionic polymer flocculant, a poly(meth)acrylamide-based flocculant having, as a nonionic monomer, a constituent unit derived from at least one selected from (meth)acrylamides is more preferred.

[0037] Furthermore, as the amphoteric polymer flocculant, a polymer flocculant of a dialkylaminoalkyl (meth)acrylate quaternary ammonium salt-(meth)acrylic acid copolymer having a structural unit derived from at least one selected from the above-mentioned dialkylaminoalkyl (meth)acrylate quaternary ammonium salts and a structural unit derived from the above-mentioned (meth)acrylic acid monomer; and a polymer flocculant of a (meth)acrylamide-dialkylaminoalkyl (meth)acrylate quaternary ammonium salt-(meth)acrylic acid copolymer having a structural unit derived from at least one selected from (meth)acrylamide are more preferred.

[0038] In one aspect of this method, the polymer flocculant preferably contains a polymer flocculant with a colloid equivalent value of 0.0 meq / g or less. That is, it preferably contains at least one selected from the group consisting of anionic polymer flocculants and nonionic polymer flocculants. By using such a polymer flocculant, the effects of preventing pile collapse, suppressing adhesion of loose material to the conveying device, improving the vibration resistance of the pile, and suppressing the outflow of suspended matter are likely to be enhanced. From the viewpoint of enhancing these effects, the colloid equivalent value of the polymer flocculant is preferably -0.5 meq / g or less, more preferably -1.1 meq / g or less, and even more preferably -1.5 meq / g or less. Furthermore, from the viewpoint of production and availability, the colloid equivalent value of the polymer flocculant is preferably -10.0 meq / g or more.

[0039] Furthermore, it is more preferable that the polymer flocculant contains a (meth)acrylamide-(meth)acrylic acid copolymer having structural units derived from at least one selected from (meth)acrylamide and structural units derived from at least one selected from the group consisting of (meth)acrylic acid and its salts. The use of these polymer flocculants further enhances the effect of preventing piles in yards from collapsing even during heavy rain and suppressing increases in moisture content. Furthermore, the vibration resistance of piles and the effect of suppressing the outflow of suspended solids are also enhanced.

[0040] In one aspect of the present method, from the viewpoint of availability, it is also preferable that the polymer flocculant contains at least one selected from the group consisting of acrylamide polymer, acrylamide-sodium acrylate copolymer, acrylamide-ammonium acrylate copolymer, and acrylamide-[2-(acryloyloxy)ethyl]trimethylammonium chloride copolymer. Among these, it is even more preferable that the polymer flocculant contains at least one selected from the group consisting of acrylamide-sodium acrylate copolymer and acrylamide-ammonium acrylate copolymer, because this tends to increase the vibration resistance of the pile and more effectively suppress the outflow of suspended solids.

[0041] The weight-average molecular weight (Mw) of the polymer flocculant is preferably 4 million to 25 million, more preferably 7 million to 23 million, and even more preferably 10 million to 20 million. The weight-average molecular weight of the polymer flocculant is a value measured by GPC (gel permeation chromatography) using polystyrene standards.

[0042] The form of the polymer flocculant when mixed with the loose material is not particularly limited, and examples include powder, as well as liquid forms such as an aqueous solution and a dispersion. Among these, a liquid form is preferred from the viewpoint of ease of addition to the loose material and ease of uniform mixing. As a liquid polymer flocculant, a chemical solution containing the polymer flocculant as an active ingredient can be used. The content of the polymer flocculant in this chemical solution is preferably 0.01 to 60 mass% based on the total mass of the chemical solution.

[0043] When using an aqueous solution of a polymer flocculant in which the polymer flocculant is dissolved in water or a diluted solution obtained by diluting a dispersion of a polymer flocculant (described later) as the chemical solution, from the viewpoint of ease of handling due to viscosity, the content of the polymer flocculant in the chemical solution is more preferably 0.01 to 10 mass% based on the total mass of the chemical solution. The content of the polymer flocculant in this chemical solution is more preferably 0.1 to 5 mass%, and particularly preferably 0.2 to 2 mass%.

[0044] When a dispersion of a polymer flocculant in which the polymer flocculant is dispersed in a dispersion medium is used as the chemical solution, the content of the polymer flocculant in the dispersion (chemical solution) is more preferably 10 to 60 mass% based on the total mass of the dispersion. The content of the polymer flocculant in this dispersion is even more preferably 10 to 50 mass%, and particularly preferably 15 to 45 mass%. As the dispersion, a dispersion of a polymer flocculant or an emulsion of a polymer flocculant can be used. As the dispersion of a polymer flocculant, a dispersion (O / W dispersion) in which the polymer flocculant is dispersed in an aqueous salt solution can be preferably used. As the aqueous salt solution, for example, an aqueous sulfate solution such as an aqueous ammonium sulfate solution or an aqueous magnesium sulfate solution can be preferably used. As the emulsion of a polymer flocculant, a water-in-oil (W / O) emulsion in which the polymer flocculant is dispersed in a hydrotreated light distillate oil (petroleum) can be preferably used.

[0045] The above-mentioned polymer flocculant can be produced by a known method. For example, the above-mentioned monomer component and a known polymerization initiator (e.g., an azo-based initiator or a peroxide-based initiator) are used to polymerize or copolymerize the monomer component by aqueous solution polymerization, water-in-oil emulsion polymerization, water-in-oil dispersion polymerization, or dispersion polymerization in saltwater. The resulting product can then be prepared in the form of an aqueous solution, water-in-oil emulsion, saltwater dispersion, or powder to produce a chemical solution (polymer flocculant product) containing the polymer flocculant as an active ingredient.

[0046] The chemical solution containing the above-mentioned polymer flocculant as an active ingredient may contain one or more other components in addition to the polymer flocculant and the liquid medium such as water or a salt solution. Examples of the other components include surfactants, dispersants, preservatives, antioxidants, colorants, and antifoaming agents.

[0047] The amount of polymer flocculant added to the bulk material (mixing amount) is preferably 0.001 to 0.4% by mass, more preferably 0.004 to 0.1% by mass, and even more preferably 0.01 to 0.04% by mass, relative to the total mass of the bulk material. In this disclosure, the "total mass of bulk material" refers to the total mass of the bulk material to be mixed with the polymer flocculant. If the bulk material contains water, this refers to the mass of the entire bulk material (hydrated bulk material) including the water. The "proportion of polymer flocculant added relative to the total mass of the bulk material" is the percentage (mass%) calculated by dividing the amount (mass) of polymer flocculant mixed with the bulk material by the total mass of the bulk material. When a chemical solution containing a polymer flocculant is used as the polymer flocculant, the "amount (mass) of polymer flocculant" refers to the amount (mass) of polymer flocculant (active ingredient) in the chemical solution.

[0048] This method involves mixing a polymer flocculant with bulk materials before they are piled in a yard. For example, when the yard in this method is a yard at a steelworks or power plant, it is preferable to mix the polymer flocculant with the bulk materials when unloading the bulk materials transported from a bulk material production site, such as coal or iron ore, by a vessel such as a bulk carrier using a loading and unloading facility, or when transporting the unloaded bulk materials to the yard using a transport device. Furthermore, when the yard in this method is a yard at a mine or mining site, the polymer flocculant may be mixed with the bulk materials when transporting them from the mining site to the yard using a transport device. Examples of the loading and unloading facility include bridge cranes, horizontal retractable cranes, grab bucket unloaders, and continuous unloaders. Examples of the transport device include belt conveyors.

[0049] Specifically, when bulk materials transported by ship from a bulk material producing area are unloaded at a loading facility, it is more preferable to add and mix the polymer flocculant to the bulk materials in the ship's hold before unloading or in the loading facility used to unload the bulk materials from the ship (for example, in the hopper of the loading facility). In this case, the means for mixing the bulk materials and the polymer flocculant is not particularly limited, and for example, a grab bucket of the loading facility may be used, or various stirring devices and mixing implements may be used.

[0050] Furthermore, when unloaded bulk materials are transported to a yard by a belt conveyor, it is even more preferable to add and mix the polymer flocculant with the bulk materials transported by the belt conveyor to the yard. In this case, the polymer flocculant can be added to the bulk materials being transported on the belt conveyor or to the bulk materials in a hopper at the joint (transfer) of the belt conveyor. Preferred methods for adding the polymer flocculant to the bulk materials on the belt conveyor include spraying the polymer flocculant-containing solution onto the bulk materials on the belt conveyor in a shower-like manner, spraying it in a mist-like manner, or letting it flow down in a straight stream similar to tap water flowing from a faucet, as well as a combination of two or three of these methods. The means for mixing the bulk materials with the polymer flocculant are not particularly limited, but include using various stirring and mixing devices in a hopper at the joint (transfer) of the belt conveyor, or utilizing the drop due to the step at the joint (transfer) of the belt conveyor. The location where the polymer flocculant is added to and mixed with the bulk material may be one of the specific examples described above, or multiple locations.

[0051] By mixing the above-mentioned polymer flocculant with bulk materials before they are piled in a yard, the adsorption action of the polymer flocculant can be used to flocculate the bulk materials in the mixture containing the bulk materials and the polymer flocculant, forming bulk flocs. Forming bulk flocs before piling them in a yard can prevent the bulk materials from collapsing after the mixture containing the bulk materials and the polymer flocculant is piled in the yard. It can also prevent powdery bulk materials from being entrained in the yard and becoming fine suspended matter and flowing away due to rainfall. Furthermore, when forming bulk flocs using the polymer flocculant, if the bulk materials contain moisture, the moisture can be captured in the gaps between the aggregated bulk materials, reducing the fluidity of the bulk materials due to moisture and thereby facilitating transport on a belt conveyor. This also prevents the bulk materials from adhering to the transport device when a certain amount of bulk materials is dispensed from the bulk material pile in the yard by a reclaimer or the like and transported to the next process. As a result, problems such as bulk material loss and clogging of the transport device can be reduced.

[0052] This method includes mixing a polymer flocculant with bulk materials before they are piled up in a yard, and then piling up the mixture containing the bulk materials and the polymer flocculant in the yard. When transporting the mixture containing the bulk materials and the polymer flocculant to the yard, a conveying device such as a belt conveyor can be used, as described above. When piling up the mixture containing the bulk materials and the polymer flocculant that has been transported to the yard by a conveying device such as a belt conveyor in the yard, the mixture can be stacked and piled up using stacking equipment.

[0053] Examples of stacking equipment include stackers and stacker-reclaimers. Stackers are used to continuously stack bulk materials such as coal and iron ore transported by belt conveyors in a yard. Stackers generally run on rails laid on the side of the yard and are equipped with a belt conveyor on a boom that can swing and rise. Stacker-reclaimers are equipment that combines the functions of both a stacker and a reclaimer. Reclaimers are equipment that continuously removes bulk materials from a yard and sends them to the next process. For example, a typical swing-boom reclaimer runs on rails laid on the side of the yard and continuously scoops up bulk materials with bucket wheels at the end of the swing-and-rise boom, which then sends them via a belt conveyor on the boom to a belt conveyor that supplies the materials to the next process.

[0054] Near the yards of steelworks, there are rails on which stacking equipment such as stackers and stacker-reclaimers run, belt conveyors installed on stacking equipment, and belt conveyors installed on unloading equipment such as reclaimers. When heavy rainfall exceeding 200 mm in a day or 30 mm, 50 mm, or 80 mm in an hour (such as record-breaking short-term heavy rainfall or torrential rain) occurs, bulk material piles in the yard can spill out or collapse, burying the rails and belt conveyors under the bulk material. This situation not only leads to equipment damage and deterioration, but also reduces the productivity of products made using the bulk material. In response to these issues, the present method not only mixes a polymer flocculant with the bulk material before it is piled up in the yard, but also uses a coating agent, described below, to treat the bulk material after it is piled up.

[0055] This method includes piling a mixture containing loose material and a polymer flocculant in a yard, and then spraying a coating agent onto the surface of the mixture piled in the yard. The coating agent is a liquid composition having film-forming properties. The coating agent preferably contains at least one resin selected from the group consisting of acrylic resins and vinyl acetate resins, and more preferably contains an acrylic resin.

[0056] As the coating agent, a coating agent containing a film-forming resin or rubber (active ingredient) and a liquid medium (solvent or dispersion medium) that dissolves or disperses the resin or rubber can be preferably used. From the viewpoints of environmental considerations and water resistance, it is preferable to use an aqueous resin emulsion or latex containing an aqueous medium containing water and polymer particles as the active ingredient dispersed in the aqueous medium (dispersion medium), and it is more preferable to use a resin emulsion. As the resin emulsion, anionic resin emulsions and nonionic resin emulsions are more preferred, and anionic resin emulsions are even more preferred.

[0057] The polymer particles contained in resin emulsions and latexes are water-insoluble because they are dispersed in an aqueous medium containing water. Examples of resins constituting the polymer particles in resin emulsions include acrylic resins, styrene resins, vinyl acetate resins, and urethane resins. Examples of rubbers constituting the polymer particles in latex include natural rubber, styrene-butadiene rubber, acrylonitrile-butadiene rubber, and chloroprene rubber. Among these, it is preferable that the polymer particles be resins, i.e., that a resin emulsion be used. The coating agent may contain one or more types of resin particles, and one or more types of resin emulsions may be used.

[0058] In the present disclosure, an acrylic resin refers to a resin in which at least a (meth)acrylic acid ester is used as a polymerizable monomer component constituting the resin, and has structural units derived from the (meth)acrylic acid ester. A styrene-based resin refers to a resin in which at least a styrene-based monomer is used as a polymerizable monomer component constituting the resin (however, this excludes those corresponding to the acrylic resins in the present disclosure), and has structural units derived from the styrene-based monomer. A vinyl acetate-based resin refers to a resin in which at least vinyl acetate is used as a polymerizable monomer component constituting the resin (however, this excludes those corresponding to the acrylic resins and the styrene-based resins in the present disclosure), and has structural units derived from vinyl acetate. Specific examples of monomers that can constitute each resin are listed below for the purpose of explanation, but are not limited to these exemplary monomers.

[0059] Examples of (meth)acrylic acid esters used in acrylic resins include (meth)acrylic acid alkyl esters having a linear, branched, or cyclic alkyl group. Examples of (meth)acrylic acid alkyl esters include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, and isobornyl (meth)acrylate. The alkyl group in the (meth)acrylic acid alkyl ester may have a substituent such as an aryl group, a hydroxy group, or an alkoxy group. Examples of the alkyl ester include benzyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, polyethylene glycol mono(meth)acrylate, 2-methoxyethyl (meth)acrylate, and methoxypolyethylene glycol mono(meth)acrylate. The polymerizable monomer component constituting the acrylic resin can be one or more types of (meth)acrylic acid esters, and can also be one or more types of other polymerizable monomers copolymerizable with the (meth)acrylic acid esters. Examples of other polymerizable monomers include the monomers mentioned in the description of styrene-based resins and vinyl acetate-based resins described below, as well as other monomers described below.

[0060] Examples of styrene-based monomers used in styrene-based resins and the like include styrene and styrene derivatives. Examples of styrene derivatives include α-methylstyrene, 2-, 3-, and 4-methylstyrene, and 2-, 3-, and 4-ethylstyrene. As the polymerizable monomer component constituting the styrene-based resin, one or more styrene-based monomers can be used, and one or more other polymerizable monomers copolymerizable with the styrene-based monomer can also be used. Examples of other polymerizable monomers include the monomers mentioned in the description of vinyl acetate-based resins described below, as well as other monomers described below.

[0061] Polymerizable monomers used in vinyl acetate resins include vinyl acetate, ethylene, vinyl chloride, etc., and one or more of these may be used. Examples of vinyl acetate resins include polyvinyl acetate, ethylene-vinyl acetate copolymer, and vinyl chloride-vinyl acetate copolymer. Among these, ethylene-vinyl acetate copolymer is preferred.

[0062] In addition to the above-mentioned monomers, other monomers can also be used as polymerizable monomer components constituting resins such as acrylic resins and styrene resins. Examples of such other monomers include unsaturated carboxylic acid monomers, (meth)acrylamide and its derivatives, acrylonitrile, and methacrylonitrile. Styrenic resins and acrylic resins preferably contain structural units derived from unsaturated carboxylic acid monomers so that they can be dispersed in aqueous media. Examples of unsaturated carboxylic acid monomers include unsaturated carboxylic acids such as (meth)acrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, and citraconic acid; and unsaturated carboxylic acid anhydrides such as maleic anhydride and itaconic anhydride. One or more of these unsaturated carboxylic acid monomers can be used. Among unsaturated carboxylic acid monomers, (meth)acrylic acid is preferred.

[0063] The synthesis method of the acrylic resin, styrene resin, and vinyl acetate resin is not particularly limited, and they can be produced by a known polymerization method such as radical polymerization, etc. For example, a method such as emulsion polymerization or suspension polymerization can be used using the above-mentioned polymerizable monomer components and polymerization initiators.

[0064] The urethane resin in the present disclosure is a resin having a urethane bond in the molecule. Examples of the urethane resin include, in addition to urethane resin, urethane urea resin having a urea bond in the molecule, acrylic urethane resin having an acryloyloxy group and / or a methacryloyloxy group in the molecule, and silicone-modified urethane resin having a siloxane bond in the molecule.

[0065] The synthesis method of the urethane resin emulsion is not particularly limited, and it can be produced by a known synthesis method. For example, the urethane resin obtained by reacting raw materials containing a polyol and a polyisocyanate, and optionally further containing a polyamine, a crosslinking agent, a chain extender, etc., can be emulsified by a method such as forced emulsification or self-emulsification to produce the urethane resin emulsion. When emulsifying by self-emulsification, a polyol having an acid group can also be used as a raw material.

[0066] Examples of polyols that can be used in the synthesis of urethane-based resins include polyester polyols, polyether polyols, polycarbonate polyols, and acrylic polyols. Examples of polyisocyanates include various aliphatic polyisocyanates and aromatic polyisocyanates. Examples of polyols having an acid group include 2,2-dimethylolpropionic acid and 2,2-dimethylolbutanoic acid.

[0067] The glass transition temperature (Tg) of the resin in the resin emulsion is preferably −80 to 100° C., more preferably −30 to 80° C., and even more preferably −10 to 70° C. In the present disclosure, the glass transition temperature of the resin can be a value measured by differential scanning calorimetry (DSC). In addition, the cumulative 50% particle diameter (D 50) is preferably 20 to 1500 nm, more preferably 30 to 1300 nm, and even more preferably 40 to 1000 nm. In the present disclosure, the cumulative 50% particle size in the volume-based particle size distribution of the resin can be a value measured using a particle size distribution measuring device using a laser diffraction / scattering method. Furthermore, the minimum film forming temperature (MFT) of the resin emulsion as specified in JIS K6828-2:2003 is preferably -10 to 65°C, more preferably -5 to 60°C, and even more preferably 0 to 50°C.

[0068] The resin emulsion preferably contains at least one resin selected from the group consisting of acrylic resins and vinyl acetate resins, and more preferably contains an acrylic resin. That is, the coating agent preferably contains at least one resin particle selected from the group consisting of acrylic resin particles and vinyl acetate resin particles, and more preferably contains acrylic resin particles. In addition, from the viewpoint of easily increasing the effect of suppressing an increase in moisture content and easily increasing the vibration resistance of the pile, it is preferable to use a coating agent having a cumulative 50% particle diameter (median diameter (D)) in the volume-based particle size distribution of the acrylic resin particles or vinyl acetate resin particles measured by a laser diffraction / scattering method. 50 )) is preferably less than 500 nm, more preferably 250 nm or less, even more preferably 150 nm or less, and is preferably 10 nm or more. D of the resin particles in the aqueous resin emulsion used as a coating agent in the examples and comparative examples described later 50 (nm) is a value measured using a laser diffraction / scattering particle size distribution measuring device.

[0069] In addition to the resin or rubber and the liquid medium, the coating agent may contain one or more other components, such as surfactants, dispersants, preservatives, antioxidants, UV absorbers, light stabilizers, anti-settling agents, viscosity modifiers, and anti-foaming agents.

[0070] The content of polymer particles (resin or rubber) as an active ingredient in the coating agent is preferably 1 to 50 mass %, more preferably 2 to 20 mass %, and even more preferably 3 to 10 mass %, based on the total mass of the coating agent. By having the content of polymer particles as an active ingredient in the coating agent within the above range, it is easy to evenly distribute the active ingredient in the coating agent over the entire pile.

[0071] The amount of coating agent to be added (sprayed) to the mixture containing loose material and polymer flocculant is 1 to 1000 g / m2, calculated as the amount of coating agent to be added (sprayed) to the surface area of ​​the pile of the mixture containing loose material and polymer flocculant. 2 It is preferable that the density is 20 to 500 g / m 2 More preferably, it is 40 to 120 g / m 2 The above-mentioned "amount of coating agent added (amount of application) relative to the surface area of ​​the pile of the mixture containing the bulk material and the polymer flocculant" is calculated by multiplying the mass (g) of the coating agent in terms of the active ingredient to be applied to the pile by the surface area (m 2 ) and calculate the value (g / m 2 The above "mass (g) of the coating agent converted into the active ingredient" refers to the mass of the resin (active ingredient) in the coating agent when, for example, a coating agent containing a resin and a liquid medium is used.

[0072] The coating agent can be sprayed on the surface of the mixture containing bulk materials and polymer flocculant piled up in a yard by spraying the coating agent in shower or mist form on the surface of the pile in the yard. Specifically, it is preferable to spray the coating agent on the surface (slope) of the pile in the yard using a sprinkler device attached to the stacking equipment such as the above-mentioned stacker and stacker-reclaimer.

[0073] By spraying the above-mentioned coating agent on the surface of piles (mixtures containing bulk materials and polymer flocculants) piled up in a yard, the active ingredients of the coating agent, such as resin, cover and harden the surface of the pile, making it possible to prevent flooding due to rainfall. Therefore, even during heavy rain, it is possible to prevent an increase in moisture content. It is also expected to have an effect on vibration resistance of the pile.

[0074] As described above, this method involves mixing a polymer flocculant with bulk materials before they are piled in a yard. This allows the mixture containing the bulk materials and the polymer flocculant to flocculate the bulk materials and form a bulk floc. In addition, this method also involves spraying a coating agent on the surface of the mixture containing the bulk materials and the polymer flocculant piled in the yard, thereby preventing rainwater from seeping into the piles in the yard. In this way, this method uses the polymer flocculant to form bulk flocs throughout the pile, including the interior and surface, while the coating agent prevents water from seeping into the piles. Therefore, even during heavy rain, the piles in the yard are less likely to collapse, preventing an increase in moisture content. Furthermore, this method also prevents bulk materials such as powdered iron ore and coal from becoming entrained in large amounts of rainwater during heavy rain and becoming fine suspended solids, which can be expected to reduce the amount of suspended solids that flow out. Furthermore, it is expected that the vibration resistance of the pile will be improved, which will make it easier to maintain the effect of making the pile less likely to collapse and the effect of suppressing an increase in moisture content.

[0075] The method for piling loose items according to one embodiment of the present invention can have the following configuration. [1] A method of piling bulk materials in a yard, comprising: mixing a polymeric flocculant with the bulk material before it is piled in the yard; piling the mixture containing the bulk material and the polymer flocculant in the yard; and spraying a coating agent onto the surface of the mixture piled in the yard; How to stack loose items, including: [2] A method for piling bulk materials according to the above [1], wherein the polymer flocculant contains a polymer flocculant with a colloid equivalent value of 0.0 meq / g or less. [3] A method for piling bulk materials according to [1] or [2] above, wherein the polymer flocculant contains a (meth)acrylamide-(meth)acrylic acid copolymer having a constituent unit derived from at least one selected from (meth)acrylamide and a constituent unit derived from at least one selected from the group consisting of (meth)acrylic acid and its salts. [4] A method for piling bulk materials according to [1] or [2] above, wherein the polymer flocculant comprises at least one selected from the group consisting of acrylamide polymer, acrylamide-sodium acrylate copolymer, acrylamide-ammonium acrylate copolymer, and acrylamide-[2-(acryloyloxy)ethyl]trimethylammonium chloride copolymer. [5] A method for piling bulk materials according to any one of [1] to [4] above, wherein the polymer flocculant comprises at least one selected from the group consisting of an acrylamide-sodium acrylate copolymer and an acrylamide-ammonium acrylate copolymer. [6] The coating agent contains at least one type of resin particles selected from the group consisting of acrylic resin particles and vinyl acetate resin particles, The method for piling bulk materials according to any one of [1] to [5] above, wherein the resin particles have a cumulative 50% particle size of less than 500 nm in a volume-based particle size distribution measured by a laser diffraction / scattering method. [Example]

[0076] Below, examples and comparative examples (hereinafter, these may be collectively referred to as "test examples") will be given to further explain in detail the effects of the bulk pile stacking method of one embodiment of the present invention.

[0077] <Examples and Comparative Examples> 〔material〕 Commercially available coal (common coal (blend coal) manufactured by Sanyo Kosho Co., Ltd., moisture content approximately 10% by mass) was used as bulk coal, sieved to a particle size of 5 mm or less. The polymer flocculants shown in Table 1 and the coating agents shown in Table 2 were also used. These polymer flocculants and coating agents were commercially available products, and when used in the tests described below, they were diluted with pure water to the amount of active ingredient shown in the right column ("When Used" column) of Tables 1 and 2. For convenience, these diluted solutions of polymer flocculants and coating agents are collectively referred to as "agents," and each agent is referred to as Agents P1 to P7. The colloid equivalent values ​​of the polymer flocculants shown in Table 1 are within the product specification range. The colloid equivalent values ​​of each polymer flocculant actually used in the examples and comparative examples were measured using the measurement method described below, and it was confirmed that all polymer flocculants were within the product specification range shown in Table 1.

[0078] TIFF2026015230000001.tif117170

[0079] TIFF2026015230000002.tif63170

[0080] (ionicity of polymer flocculant) The ionicity of each polymer flocculant product shown in Table 1 was confirmed based on the product specification value of colloidal equivalent value and the colloidal equivalent value (meq / g) measured by the procedure described below.

[0081] (Preparation of polymer flocculant solution) For each polymer flocculant, the liquid polymer flocculant product was added to 200 mL of pure water and stirred with a magnetic stirrer for 30 minutes to prepare a polymer flocculant solution. The mass of the liquid polymer flocculant product used at this time was defined as s (g; approximate value: 0.1 g).

[0082] (Confirmation of the amount of active ingredient in polymer flocculant) Approximately 1.0 g of each liquid polymer flocculant product sample was weighed onto an aluminum dish and dried in a dryer at 105±5°C for 24 hours, after which the mass was measured. The mass before drying was designated M1, and the mass after drying was designated M2. The active ingredient (polymer flocculant) concentration c of each liquid polymer flocculant product was calculated using the following formula (1): Active ingredient concentration c (mass%) = M2 / M1×100 (1)

[0083] (Measurement of colloidal equivalent value of polymer flocculants used in agents P1, P2, and P5) The colloid equivalent value per gram of polymer flocculant used in formulations P1, P2, and P5 was measured as follows. A 300 mL Erlenmeyer flask was charged with 90 mL of pure water, 0.5 mL of 0.1 mol / L sodium hydroxide solution, and 5 mL of 5 mmol / L methyl glycol chitosan solution (Fujifilm Wako Pure Chemical Industries, Ltd.'s "N / 200 MeGch solution" for colloid titration, factor F = 1.00). After stirring for at least 1 minute, 10 mL of polymer flocculant solution was gradually added and stirred for at least 5 minutes. This was used as the test solution. A few drops of toluidine blue indicator were added to the test solution to turn it blue, and then 2.5 mmol / L polyvinyl potassium sulfate solution (Fujifilm Wako Pure Chemical Industries, Ltd.'s "N / 400 PVSK solution" for colloid titration, factor F = 1.00) was added dropwise. The endpoint was the point at which the test solution changed from blue to reddish purple and the reddish purple color remained for at least 10 seconds. The titer a (mL) of 2.5 mmol / L polyvinyl potassium sulfate solution required to achieve this was determined. Separately, a blank test was performed using 100 mL of pure water instead of the test solution, and the titer b (mL) of 2.5 mmol / L polyvinyl potassium sulfate solution required to reach the same endpoint was determined. The colloid equivalent (meq / g) per gram of each polymer flocculant (active ingredient) used in formulations P1, P2, and P5 was calculated using the following formula (2): Colloid equivalent value (meq / g) ={(ab) / 2}×{10 / (s×c)}×F ···(2)

[0084] (Measurement of colloid equivalent value of polymer flocculants used in drugs P3 and P4) The colloid equivalent value per gram of polymer flocculant used in Agents P3 and P4 was measured as follows. 90 mL of pure water and 10 mL of polymer flocculant solution were placed in a 300 mL Erlenmeyer flask, stirred, and then 0.1 mol / L hydrochloric acid was added to adjust the pH to 4. This polymer flocculant solution was used as the test solution. A few drops of toluidine blue indicator solution were added to the test solution to turn it blue, and 2.5 mmol / L polyvinyl potassium sulfate solution (Fujifilm Wako Pure Chemical Industries, Ltd., "N / 400 PVSK solution" for colloid titration, factor F = 1.00) was added dropwise. The test solution changed from blue to reddish purple, and the point at which the reddish purple color persisted for approximately 10 seconds or more was considered the endpoint. The amount of 2.5 mmol / L polyvinyl potassium sulfate solution required for this change was determined. Separately, a similar procedure (blank test) was performed using 100 mL of pure water instead of the test solution, and the titer b (mL) of 2.5 mmol / L potassium polyvinyl sulfate solution required to reach the same end point was determined. The colloid equivalent value (meq / g) per gram of the polymer flocculant (active ingredient) used in Agents P3 and P4 was calculated using the above formula (2).

[0085] [Collapse test] Assuming the collapse of a pile of loose material in a yard due to heavy rain, we conducted a test to confirm the effectiveness of the above-mentioned chemicals and coal in suppressing the collapse of a pile of coal (collapse suppression effect). First, a plastic mold 11 was prepared to simulate a portion of a pile in a yard, as shown in Figure 1. This plastic mold 11 is a triangular prism with two opposing right-angled triangles. The surface (slope) portion 12 corresponding to the hypotenuse of the right-angled triangle is open, and the slope portion 12 is machined so that the angle of repose, i.e., the inclination angle θ1, formed by the slope portion 12 and a horizontal plane 13, is 37°. When using this plastic mold 11, the horizontal plane 13 is placed on a horizontal table so that the open slope portion 12 faces upward. A sample containing coal can be loaded into the plastic mold 11 through the open slope portion 12, and 2500 g of the coal can be leveled into the slope portion 12. In Comparative Example 1, which was a blank test in which no chemical agent was used, 2500 g of the above coal as a sample was filled into the slope portion 12 of a plastic mold 11 by leveling.

[0086] Table 3 shows an overview of the test conditions. The "Addition Order" column in Table 3 indicates the order in which the chemicals were added (mixed or sprayed) to the coal. In each of the Examples and Comparative Examples other than Comparative Example 1, the "sample" described below refers to coal to which the chemicals were added (mixed and / or sprayed). The test method will now be described in detail.

[0087] TIFF2026015230000003.tif170170

[0088] Coal without any added chemicals (test examples without "mixed" in the "Addition Method" column in Table 3) or coal mixed with a chemical indicated as "mixed" in the "Addition Method" column in Table 3 was filled into plastic mold 11 by leveling into sloped portion 12. In test examples (each Example and Comparative Examples 3, 5-7, and 9-11) in which a chemical indicated as "mixed" in the "Addition Method" column in Table 3 was mixed with coal, the chemical was added to the coal in a separate container in an amount (mass %) indicated in the "Addition Amount" column in Table 3 in terms of the active ingredient relative to the total mass of the coal, and mixed. The mixture containing the coal and the chemicals was then filled into plastic mold 11. In test examples (Comparative Examples 10 and 11) in which two types of chemicals were mixed with coal, the first type of chemical was added to the coal and mixed, and then the second type of chemical was immediately added and mixed thereto, and the resulting mixture containing the coal and the two chemicals was filled into plastic mold 11.

[0089] Next, test examples that do not have "spreading" indicated in the "method of addition" column in Table 3 were left to stand for 24 hours. In test examples (each Example and Comparative Examples 2, 4, 8, 9, and 12) that used an agent indicated as "spreading" in the "method of addition" column in Table 3, the agent indicated as "spreading" in the "method of addition" column in Table 3 was sprayed onto the open sloped portion 12 of the plastic mold 11 filled with coal or coal mixed with an agent, and then left to stand for 24 hours. The amount of agent added (spreading amount) to be "spread" onto the coal or coal containing the agent "mixed" was the amount of the agent added in terms of the active ingredient relative to the area of ​​the sloped portion 12 shown in the "amount added" column in Table 3 (g / m 2In a test example (Comparative Example 8) in which two types of chemicals were sprayed on the sloped surface 12 of the plastic mold 11, the first type of chemical was sprayed, followed immediately by the second type of chemical, and the mixture was left to stand for 24 hours.

[0090] Finally, water was sprayed from above the sloped portion 12 of the plastic mold 11, which was filled with coal without any chemical additives in Comparative Example 1, or coal with chemical additives (mixed and / or sprayed) in all other cases, simulating heavy rain. The simulated rainfall was sprayed in the following order: (i) 40 mm / h for 60 minutes, (ii) 120 mm / h for 60 minutes, and (iii) 180 mm / h for 60 minutes or more, for a total of 180 minutes or more and a total rainfall of 340 mm or more. The test was terminated when the samples collapsed from the sloped portion 12. For example, if the samples collapsed from the sloped portion 12 of the plastic mold 11 during watering condition (i), this indicates that the pile of samples, under these test conditions, could not withstand 40 mm / h rain for one hour or could collapse if the total rainfall reached 40 mm. For example, if the samples fall off the sloped portion 12 of the plastic mold 11 during watering condition (ii) after watering condition (i), this indicates that the pile of samples cannot withstand rain at 120 mm / h for one hour under these test conditions, or that the pile may collapse if the total rainfall reaches 160 mm even with lighter rain. Furthermore, if the samples do not fall off the sloped portion 12 of the plastic mold 11 even after 60 minutes of watering condition (iii), this indicates that the pile of samples can withstand rain at 180 mm / h for one hour or more, or that the pile of samples can withstand a total rainfall of 340 mm or more under these test conditions.

[0091] The time (minutes; hereinafter also referred to as "time required for collapse") required for the sample to collapse from the sloped portion 12 of the plastic mold 11 after the start of watering under the above watering conditions, and the total amount of precipitation (mm) at that time were recorded. The effect of suppressing the collapse of the coal pile was then evaluated according to the following evaluation criteria. These results are shown in Table 4 below. AA: The sample did not collapse even with a total rainfall of 160 mm (after watering condition (ii)). A: The total precipitation was between 61mm and 160mm, and the sample collapsed from the slope. B: The total precipitation was between 34mm and 60mm, and the sample collapsed from the slope. C: The total precipitation was less than 33 mm and the sample collapsed from the slope.

[0092] [Adhesion test] Assuming adhesion of a predetermined amount of loose coal to a transport device when it is removed from a pile after heavy rain in a yard and transported, a test was conducted to confirm the effectiveness of the adhesion suppression (adhesion suppression effect) of the coal removed from the pile after heavy rain using samples after the collapse test described above. Specifically, in each example and comparative example, a sample was collected from near the center 14 (see Figure 1) of the plastic mold 11 at the end of the collapse test described above (the point at which the sample collapsed from the sloped portion 12 of the plastic mold 11 after the start of water spraying). As shown in Figure 2, 10 g of the collected sample 20 was placed on a stainless steel tray 21 serving as a simulated transport device, and the tray 21 was tilted 30°. The time (seconds) until the sample 20 slid down 200 mm from the bottom end 20a of the tray was measured and recorded as the sliding time. The adhesion suppression effect of the coal removed from the pile after heavy rain was evaluated according to the following evaluation criteria. The results are shown in Table 4 below. It can be said that the shorter the sliding time, the less likely the coal is to adhere to a conveying device such as a belt conveyor. AA: The fall lasted less than 1 second. A: The fall time was between 2 and 9 seconds. B: The fall time was between 10 and 19 seconds. C: The fall lasted for more than 20 seconds.

[0093] [Moisture content measurement test] A test was conducted to verify the effectiveness of the method in suppressing the increase in moisture content of coal inside a pile of loose coal (moisture content increase suppression effect), assuming flooding of the inside of the pile of loose coal after heavy rain in a yard. First, to simulate a portion of a pile in a yard, a rigid polyvinyl chloride inclined cylindrical container 31 with an upwardly opening sloped portion 32 was prepared, as shown in Figure 3. This inclined cylindrical container 31 had an inner diameter of 50 mm, a height from the bottom 33 to the lower slope 32a of 90 mm, a height from the bottom 33 to the upper slope 32b of 130 mm, and an inclination angle θ2, which is the angle of repose between a plane parallel to the bottom 33 and a plane parallel to the sloped portion 32 placed on a horizontal table, of 37°. A sample containing coal could be loaded into the inclined cylindrical container 31 through the open sloped portion 32, and 250 g of the coal could be leveled and loaded into the sloped portion 32. In Comparative Example 1, which was a blank test in which no chemical agent was used, 250 g of the above coal as a sample was filled into an inclined cylindrical container 31 by leveling the inclined surface 32 .

[0094] The test was carried out according to the following steps (1) to (3). (1) Samples for moisture content measurement were prepared according to the type of chemicals P1 to P7 (polymer flocculant or coating agent) and the addition method ("mixing" or "spraying") shown in Table 3, as shown in (1-1) to (1-5) below.

[0095] (1-1) When the chemical addition method is "spreading" only and chemical P1 is "spreading" (Comparative Examples 4 and 8), 80% of the coal without chemical addition is filled into the inclined cylindrical container 31, and then the remaining 20% ​​of the coal without chemical addition is poured on top of that, and the amount of the added active ingredient converted to 1.4 g / m2 is poured onto the surface area of ​​the inclined portion 32 of the inclined cylindrical container 31. 2 The mixture was filled with the drug P1 in an amount of 0.1g.

[0096] (1-2) When the chemical addition method is "spreading" only, and chemical P6 or P7 is "spreading" (Comparative Examples 2, 8, and 12), in Comparative Examples 2 and 12, coal without chemical addition is filled into the inclined cylindrical vessel 31, and in Comparative Example 8, the procedure of (1-1) above is carried out, and then chemical P6 or P7 is applied to the coal on the inclined portion 32 of the inclined cylindrical vessel 31 in an amount of 80 g / m2 of active ingredient equivalent to the area of ​​the inclined portion 32 of the inclined cylindrical vessel 31. 2 It was sprayed in the amount of

[0097] (1-3) When the chemical addition method was "mixing" only, and chemical P1 and / or chemical P6 were "mixed" (Comparative Examples 3, 5-7, 10, and 11), chemical-free coal was mixed in a separate container with chemical P1 or P6 in the amount (mass %) of the chemical added in terms of the active ingredient relative to the total mass of the coal shown in the "Amount Added" column in Table 3, and the mixture was then filled into the inclined cylindrical container 31. When two types of chemicals were used (Comparative Examples 10 and 11), the first chemical P1 was added to the coal and mixed in the separate container, and then the second chemical P6 was immediately added and mixed, and the mixture was filled into the inclined cylindrical container 31.

[0098] (1-4) In the case of Comparative Example 9, a premix was prepared by mixing coal without any additives with an amount of additive P6 equivalent to 0.1% by mass of the active ingredient relative to the total mass of the coal in a separate container. 80% of the premix was then filled into the inclined cylindrical container 31, and the remaining 20% ​​of the premix and an additive amount equivalent to 1.4 g / m of the active ingredient relative to the area of ​​the inclined portion 32 of the inclined cylindrical container 31 were then poured on top of the premix. 2 The mixture was filled with the drug P1 in an amount of 0.1g.

[0099] (1-5) In each example, coal without any added chemical was mixed with a chemical (one of P1 to P5) in an amount (mass %) shown in the "Amount Added" column in Table 3, calculated as the active ingredient relative to the total mass of the coal, in a separate container, and the mixture was filled into an inclined cylindrical container 31. Thereafter, chemical P6 or P7 was applied onto the coal on the inclined portion 32 of the inclined cylindrical container 31 in an amount calculated as the active ingredient relative to the area of ​​the inclined portion 32 of the inclined cylindrical container 31 of 80 g / m 2 It was sprayed in the amount of

[0100] (2) After carrying out the procedure in (1) above, the container was left to stand for 24 hours indoors. After that, water was sprayed from above the inclined portion 32 of the inclined cylindrical container 31 filled with the sample at a precipitation rate of 40 mm / h for 30 minutes, simulating heavy rain.

[0101] (3) After watering, a sample was taken from the center 34 of the inclined cylindrical container 31 at a height of 30 mm from the bottom 33, and the moisture content (mass %) of the sample was measured. A higher moisture content indicates that more water has penetrated into the coal pile, and a lower moisture content indicates that the penetration of water into the coal pile has been suppressed.

[0102] Based on the moisture content measurement results described above, the effect of suppressing the increase in moisture content of coal inside the pile after heavy rain was evaluated according to the following evaluation criteria. AA: The moisture content was 15% by mass or less. A: The moisture content was 16% by mass or more and 20% by mass or less. B: The moisture content was 21% by mass or more and 25% by mass or less. C: The moisture content was 26% by mass or more.

[0103] [Vibration resistance of piles] Piles were prepared under conditions similar to those used in the collapse test described above, and a test was conducted to evaluate the sample's vibration resistance (a characteristic related to the ability of the coating agent to prevent cracks and tears in the sample's coating). First, a plastic cup (trade name "Fujiplacup 3oz," manufactured by Shobido Co., Ltd.; hereafter referred to as "Placup") was filled with 65 g of a sample containing coal. Specifically, 65 g of untreated coal (test examples without "mixed" in the "Addition Method" column in Table 3) or coal mixed with a chemical agent indicated as "mixed" in the "Addition Method" column in Table 3 was filled into the plastic cup. In the test examples (each Example and Comparative Examples 3, 5-7, and 9-11) in which the chemicals indicated as "mixed" in the "Addition method" column in Table 3 were mixed with coal, the chemicals were added to the coal in a separate container in the amount (mass %) indicated in the "Addition amount" column in Table 3, calculated as the active ingredient of the chemical relative to the total mass of the coal, and the mixture containing the coal and chemicals was then filled into the plastic cup. In the test examples (Comparative Examples 10 and 11) in which two chemicals were mixed with coal, the first chemical was added to the coal and mixed, and then the second chemical was immediately added and mixed, and the resulting mixture containing the coal and two chemicals was filled into the plastic cup.

[0104] Next, the plastic cup filled with the sample was inverted into a rectangular parallelepiped plastic container (internal dimensions: width (depth) 154 mm, length 230 mm, and height 57 mm) with dividers forming four compartments and an open top, and the molded sample (hereinafter referred to as "molded sample") was transferred into the plastic container. Test examples that do not have "spray" indicated in the "Addition method" column in Table 3 were left to stand for 24 hours. In test examples (each Example and Comparative Examples 2, 4, 8, 9, and 12) in which an agent indicated as "spray" in the "Addition method" column in Table 3 was used, the agent indicated as "spray" in the "Addition method" column in Table 3 was sprayed onto the molded sample and left to stand for 24 hours. The amount of agent added (spray amount) was determined by the amount of the agent added in terms of the active ingredient relative to the surface area of ​​the side of the molded sample shown in the "Addition amount" column in Table 3 (g / m 2In a test example in which two types of pesticides were sprayed (Comparative Example 8), the first type of pesticide was sprayed, followed immediately by the second type of pesticide, and the mixture was left to stand for 24 hours.

[0105] The side of the plastic container with the molded sample placed therein was struck, and the number of strikes (maximum 20 times) until the molded sample collapsed was recorded. The vibration resistance of the pile was evaluated according to the evaluation criteria shown below. AA: It didn't crumble even after 20 hits. A: It took more than 11 but less than 20 hits before it collapsed. B: It took more than 6 but less than 10 hits before it collapsed. C: It took less than five hits before it collapsed.

[0106] [Suspended matter outflow test] A test was conducted to confirm the effectiveness of the method for suppressing the outflow of suspended solids from piles. A polyvinyl chloride (PVC) pipe was filled with samples under conditions similar to those described in the collapse test. When water was poured through the sample, the amount of suspended solids (SS) released from the sample into the water (SS amount) was measured. A polyester mesh sheet (60 meshes) was fixed to one open end of a 50-mm-diameter, 200-mm-tall PVC pipe (hereafter referred to as the "PVC pipe"), with the mesh sheet side positioned at the bottom and the other open end positioned at the top. 100 g of a sample containing coal was then poured into the PVC pipe from the top. Specifically, 100 g of untreated coal (test examples without "mixed" in the "Addition Method" column in Table 3) or coal mixed with a chemical listed as "mixed" in the "Addition Method" column in Table 3 was placed in the PVC pipe, and the PVC pipe was dropped 30 times to consolidate the contents. In the test examples (each Example and Comparative Examples 3, 5-7, and 9-11) in which the chemicals indicated as "mixed" in the "Addition method" column in Table 3 were mixed with coal, the chemicals were added to the coal in a separate container in the amount (mass %) indicated in the "Addition amount" column in Table 3, calculated as the active ingredient of the chemical relative to the total mass of the coal, and the mixture containing the coal and chemicals was then placed in the PVC pipe. In the test examples (Comparative Examples 10 and 11) in which two chemicals were mixed with coal, the first chemical was added to the coal and mixed, and then the second chemical was immediately added and mixed, and the resulting mixture containing the coal and two chemicals was placed in the PVC pipe.

[0107] Next, test examples that do not have "spray" indicated in the "method of addition" column in Table 3 were left to stand for 24 hours. In test examples (each Example and Comparative Examples 2, 4, 8, 9, and 12) that used an agent indicated as "spray" in the "method of addition" column in Table 3, the agent indicated as "spray" in the "method of addition" column in Table 3 was sprayed onto the surface of the sample from the upper open end of the PVC pipe filled with the sample, and then left to stand for 24 hours. The amount of agent added (spray amount) was the amount of the agent added in terms of the active ingredient relative to the surface area of ​​the sample shown in the "amount added" column in Table 3 (g / m 2 In a test example in which two types of pesticides were sprayed (Comparative Example 8), the first type of pesticide was sprayed, followed immediately by the second type of pesticide, and the mixture was left to stand for 24 hours.

[0108] 200 mL of water was passed through the upper open end of the PVC pipe, and the water that fell from the bottom of the PVC pipe over a 5-minute period was collected. The suspended solids (SS) concentration in the collected water was measured according to JIS K 0102:2019. The amount of SS (mg) that flowed out was calculated from the measured suspended solids (SS) concentration (mg / L) and the amount of water collected (L). The effectiveness of the device in suppressing the outflow of suspended solids was evaluated according to the following evaluation criteria. AA: The amount of SS that leaked was less than 150 mg. A: The amount of SS that leaked was between 150 mg and 249 mg. B: The amount of SS that leaked was between 250 mg and 419 mg. C: The amount of SS that leaked was 420 mg or more.

[0109] TIFF2026015230000004.tif168170

[0110] From the results of the above examples and comparative examples, it can be seen that mixing a polymer flocculant with loose material before it is piled up and then spraying a coating agent on the surface of the pile made of that mixture can effectively prevent the pile from collapsing, even during heavy rain. In addition, it can be seen that it is possible to suppress an increase in moisture content and to prevent loose material from adhering to the conveying device when it is removed from the pile and transported. Furthermore, it is expected that the vibration resistance of the pile will be improved, which will make it easier to maintain the above-mentioned effects. It is also expected that it will be easier to prevent powdery loose material from being entrained in rainwater and becoming fine suspended matter, which will then flow out, thereby reducing the amount of suspended matter that flows out.

Claims

1. A method of piling bulk materials in a yard, comprising: mixing a polymer flocculant with the bulk material before it is piled in the yard; piling up the mixture containing the bulk material and the polymer flocculant in the yard; and spraying a coating agent onto the surface of the mixture piled in the yard; How to stack loose items, including:

2. 2. The method for piling bulk materials according to claim 1, wherein the polymer flocculant contains a polymer flocculant having a colloid equivalent value of 0.0 meq / g or less.

3. 2. A method for piling bulk items as described in claim 1, wherein the polymer flocculant contains a (meth)acrylamide-(meth)acrylic acid copolymer having a constituent unit derived from at least one selected from (meth)acrylamide and a constituent unit derived from at least one selected from the group consisting of (meth)acrylic acid and its salts.

4. The polymer flocculant is selected from the group consisting of acrylamide polymer, acrylamide-sodium acrylate copolymer, acrylamide-ammonium acrylate copolymer, and acrylamide-[2-(acryloyloxy)ethyl]trimethylammonium chloride copolymer. The method for piling bulk materials according to claim 1, comprising at least one selected from the group consisting of acrylamide polymer, acrylamide-sodium acrylate copolymer, acrylamide-ammonium acrylate copolymer, and acrylamide-[2-(acryloyloxy)ethyl]trimethylammonium chloride copolymer.

5. 2. The method for piling bulk materials according to claim 1, wherein the polymer flocculant comprises at least one selected from the group consisting of an acrylamide-sodium acrylate copolymer and an acrylamide-ammonium acrylate copolymer.

6. the coating agent contains at least one type of resin particles selected from the group consisting of acrylic resin particles and vinyl acetate resin particles, A method for piling bulk materials as described in claim 1, wherein the cumulative 50% particle diameter in the volume-based particle size distribution of the resin particles measured by a laser diffraction / scattering method is less than 500 nm.

Images