JP2022156426A - Method for suppressing facility disorder due to mineral raw material - Google Patents

Abstract

To provide a method for suppressing facility disorders due to a mineral raw material by suppressing natural oxidation and heat generation of the mineral raw material having a particular water content and particle diameter during transfer and storage of the mineral raw material and improving handling of the mineral raw material during the transfer and storage.SOLUTION: A method for suppressing facility disorders due to a mineral raw material comprises a contact step of bringing a polymer dispersant into contact with a mineral raw material including 70 wt.% or more of a particle having a water content of 1 to 30 wt.% and a particle diameter of 8 mm or less to obtain a dispersant-containing mineral raw material. In the contact step, the mineral raw material and the polymer dispersant are brought into contact with each other so that a particle diameter of 95 wt.% or more of the polymer dispersant after the contact step is 110% or more and less than 500% relative to an average of the particle diameter of the polymer dispersant before the contact step and a water content of 95 wt.% or more of the dispersant-containing mineral raw material after the contact step is 1 to 12 wt.%.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a method for suppressing equipment failure caused by mineral raw materials.

Generally, in power plants, ironworks, mines, etc., a large amount of coal is often piled up, deposited, and stored in a coal storage place (coal yard). In addition, coke, which is a porous solid mainly composed of carbon produced by carbonizing coal at a high temperature of 1,200 ° C, is used for iron manufacturing, casting, fuel, etc. Coke is also often piled up, deposited, and stored in a coke storage place (coke yard).
In steelworks, etc., in addition to the above, sintered ore and blast furnaces are processed to make lump-shaped iron ore, powdered iron ore, and powdered limestone, which are raw materials, into a particle size and strength suitable for charging into a blast furnace. Steel mill dust and sludge discharged from , converters, electric furnaces, etc. are also piled up, accumulated and stored.
The above-mentioned coal, coke, limestone, iron ore, sintered ore, steel mill dust and sludge, etc. (hereinafter referred to as mineral raw materials) are often stored outdoors. The moisture content of the mineral raw materials in the water increases due to rainfall and water spraying for dust prevention. Problems such as clogging have occurred in combs (regardless of lattice or mesh) or hoppers for storing or temporarily placing objects to be transferred. In addition, when the mineral raw material adheres to the belt of the belt conveyor, problems such as the mineral raw material dropping at the rewinding position of the belt conveyor have occurred. As described above, the increase in the water content of the mineral raw material deteriorates the handling property of the mineral raw material, lowers the efficiency of equipment used for storing and transporting the mineral raw material, and further raises safety problems.

In addition, in the conventional transfer method for iron-making raw materials that improves the handling of slurried iron-making raw materials (Patent Document 1), rainfall and water spraying during storage make iron-making raw materials slurry, making it difficult to carry them out. In some cases, in order to improve the handling of the ironmaking raw material slurry, it is known to bring the ironmaking raw material slurry into contact with a polymeric water absorbing agent.
However, iron ore raw materials such as coal, coke, iron ore, limestone, sintered ore, and steel mill dust are rarely transported in a slurry state. In many cases, steel raw materials with high

Furthermore, the above-mentioned mineral raw materials may react with oxygen in the air during storage to cause an oxidation reaction, causing heat generation and smoke due to temperature rise, which may cause accidents such as fires in some cases. Therefore, various measures have been taken to suppress these reactions, suppress heat generation, and enable safe storage. As a countermeasure, replacing the silo and hopper with an inert gas to suppress the oxidation reaction in the facility is conceivable, but this requires a large-scale facility, which causes problems of time and cost, and is easier. It is desired that countermeasures be taken using various methods.

For example, Patent Document 2 proposes applying an inhibitor composition to coal as a method of suppressing spontaneous combustion of lumps of low-rank coal, and the inhibitor composition includes crude glycerin and VAE It is said to contain a copolymer or PVA copolymer in a ratio of 90:10 to 10:90. And by crude glycerin is meant the by-product derivatives from transesterification reactions on triglycerides, including transesterification reactions associated with the biodiesel manufacturing process, which by-products include glycerin and fatty acids, esters, salts, At least one component from methanol, tocopherols, sterols, monoglycerides, diglycerides, triglycerides and the like is described.

Further, Patent Document 3 describes a coal production method characterized by spraying a glycerin-containing solution, which is a by-product in the process of producing biodiesel, over the surface of coal to suppress low-temperature oxidation. In the above method, the moisture contained in the powder evaporates quickly and the effect is not sustainable, and it is not possible to cope with the excessive increase in moisture due to rainfall, resulting in problems such as runoff and generation of water contaminated by powder. It's becoming

U.S. Pat. No. 5,400,002 shows a liquid product using a water-soluble polymeric absorbent mixed with other ingredients for dust prevention. However, the application is dust prevention, and it is described that spraying chemicals mixed on the coal surface forms a surface resin layer to prevent dust scattering, and at the same time, it also has the effect of preventing ignition. . However, with regard to prevention of spontaneous combustion, only the effect of the surface resin layer is mentioned, and specific examples are not shown.

In addition, in Patent Document 5, a hydrogel layer film is formed on the coal pile surface layer with a superabsorbent polymer, coal, and water, and spontaneous ignition and dust generation are achieved by the same effect principle as the polymer film according to the conventional technology. Techniques for preventing are disclosed. However, this method does not provide a sufficient effect of preventing spontaneous combustion when the surface resin layer cracks or breaks due to partial transfer of the pile.

Patent Document 6 shows the application of a spontaneous ignition inhibitor containing urea as a main component. A polymeric absorbent is added as an additive to complement the effect of urea. Here, the combined use of urea and a spontaneous ignition inhibitor is an essential condition, and it is shown that ammonia gas is generated during thermal decomposition with use, and sufficient effects have not been obtained from the viewpoint of environmental safety. .

Japanese Patent No. 6041627 Japanese Patent Application Publication No. 2015-512470 JP 2011-195779 A JP-A-59-025871 JP-A-05-230480 JP 2005-194447 A

Therefore, for mineral raw materials with a high moisture content, handling during transportation is a problem from the viewpoint of safety and efficiency. From the viewpoint of safety, there is also a demand for a method of suppressing the problem of the mineral raw material itself, which has the property of generating heat due to oxidation, that is, a method of suppressing natural oxidation and heat generation during transportation and storage.

In view of the above-mentioned current situation, the present invention suppresses natural oxidation and heat generation during transportation and storage of mineral raw materials having a specific moisture content and particle size, and improves the handling of mineral raw materials during transportation and storage. It is an object of the present invention to provide a method for suppressing equipment failure caused by mineral raw materials.

In order to solve the above problems, the present inventors have made intensive studies, and as a result, rather than simply contacting a mineral raw material having a specific water content and particle size with a polymer dispersant having a high water retention capacity, The polymer dispersant has a specific particle size, and by contacting the mineral raw material and the polymer dispersant so that the mineral raw material after contact has a specific moisture content, It has been found that there is a remarkable effect of suppressing equipment failure (equipment failure due to natural oxidation of mineral raw materials, heat generation and spontaneous combustion, equipment failure due to adhesion of mineral raw materials to equipment, etc.). Arrived.

That is, the present invention is a method for suppressing equipment failure caused by mineral raw materials, wherein a mineral raw material having a moisture content of 1 to 30% by weight and containing 70% by weight or more of particles having a particle diameter of 8 mm or less is added to a polymer. a contacting step of contacting a dispersant to obtain a dispersant-containing mineral raw material; 110% or more and less than 500% with respect to the average particle diameter of the dispersant, and the water content of the dispersant-containing mineral raw material of 95% by weight or more after the contacting step is 1 to 12% by weight. and the polymer dispersant are brought into contact with each other.
In the method for suppressing equipment failure of the present invention, the average particle size of the polymer dispersant before the contacting step is preferably 5 to 1400 μm.
In the method of the present invention, the equipment failure caused by the mineral raw material is at least one selected from the group consisting of spontaneous ignition of the mineral raw material, root clogging during transportation and storage, and adhesion of the mineral raw material to the equipment. Preferably.
The mineral raw material in the method of the present invention is preferably at least one selected from the group consisting of coal, iron, coke and iron oxide.

According to the present invention, by suppressing natural oxidation and heat generation during transportation and storage of mineral raw materials having a specific moisture content and particle size, and by improving handling properties of mineral raw materials during transportation and storage, , it is possible to provide a method for suppressing equipment failures caused by mineral raw materials.
The method of the present invention can contribute to safety during transportation and storage of mineral raw materials.

The present invention is a method for suppressing equipment failure caused by mineral raw materials, wherein a mineral raw material having a water content of 1 to 30% by weight and containing 70% by weight or more of particles having a particle diameter of 8 mm or less is added with a polymer dispersant. to obtain a dispersant-containing mineral raw material, and in the contacting step, the particle size of 95% by weight or more of the polymer dispersant after the contacting step is equal to that of the polymer dispersing agent before the contacting step. 110% or more and less than 500% with respect to the average particle size of the mineral raw material, and the water content of the dispersant-containing mineral raw material of 95% by weight or more after the contacting step is 1 to 12% by weight. It is a method for suppressing equipment failure, characterized by contacting with a polymer dispersant.
In the present specification, a dispersant-containing mineral raw material is a mineral raw material containing a polymer dispersant, and can also be referred to as a mixture of a polymer dispersant and a mineral raw material.

As described above, the mineral raw material generates heat when oxidized, so if the water content of the mineral raw material is low, the possibility of spontaneous combustion increases. On the other hand, if the water content of the mineral raw material is high, it will adhere to the equipment, making it difficult to handle during storage and transportation, and lowering the efficiency and safety of the equipment. Therefore, there is a trade-off relationship between the heat generation suppression of the mineral raw material and the handleability of the mineral raw material during storage and transportation. For example, in order to suppress the heat generation of mineral raw materials, a technique is known in which surfactants or superabsorbent polymers are sprayed so as to cover the surface layer of mineral raw materials stored in piles, and water is sprayed. (Patent Document 5). However, the technique of suppressing heat generation by coating the surface layer of the mineral raw material may cause the surface layer of the deposited mineral raw material to collapse, or when the mineral raw material is transported, the surface layer coating may collapse and the heat generation suppressing effect may be lost. It has the drawback of being In addition, as a technique for suppressing or delaying the heat generation of mineral raw materials, spraying a surfactant and water on the mineral raw materials is known. However, if the moisture content of the mineral raw material rises, as mentioned above, the mineral raw material will adhere to the hopper of the storage facility and the belt conveyor of the transfer facility, causing clogging and equipment failure due to adhesion. Problems such as a decrease in equipment efficiency due to deterioration in handling and a decrease in safety arise. Therefore, conventionally, during storage of mineral raw materials, techniques for suppressing heat generation due to oxidation of mineral raw materials have been implemented, and during transportation of mineral raw materials, techniques for preventing and suppressing adhesion of mineral raw materials have been implemented. .
The present invention is a method for suppressing equipment failures (spontaneous ignition of mineral raw materials, clogging during transfer and storage, adhesion of mineral raw materials to equipment, etc.) caused by heat generation due to oxidation of mineral raw materials, adhesion of mineral raw materials, etc. , and the problems that have been considered separately in the past are solved by a single method (that is, the method of the present invention).

The present inventors brought a mineral raw material having a specific moisture content and a specific particle size into contact with a polymer dispersant under specific conditions to suppress heat generation due to oxidation of the mineral raw material. The inventors have found that it is possible to suppress obstacles due to adhesion (e.g. root clogging during transportation and storage, adhesion of mineral raw materials to equipment) and improve the safety and handleability of mineral raw materials, and completed the present invention. .

The type of mineral raw material to be subjected to the method of the present invention is not particularly limited as long as it generates heat by oxidation. Examples include coal, iron, coke, iron oxide, limestone, iron ore, sintered ore, and steel mill dust and sludge. These may be used singly or as a mixture of two or more. As used herein, the term "mineral raw material" includes mineral raw materials themselves and mineral raw materials subjected to pretreatments such as pulverization, particle size adjustment, agglomeration, agglomeration, and granulation depending on the application. For example, when the "mineral raw material" is "coal", it includes the coal itself and the coal that has undergone pretreatment such as pulverization, particle size adjustment, agglomeration, agglomeration, and granulation depending on the application.
The mineral raw material is preferably at least one selected from the group consisting of coal, iron, coke and iron oxide.

The mineral raw material in the present invention has a water content of 1 to 30% by weight. In general, mineral raw materials with a water content of more than 30% by weight are slurried, and the frequency of use is extremely reduced. In addition, since the slurried mineral raw material has fluidity, it is less likely to adhere to equipment and the like, and is less likely to generate heat or spontaneously ignite due to oxidation. That is, the mineral raw material having a water content of more than 30% by weight is in a state where it is difficult for equipment failure to occur, so the mineral raw material in the present invention has a water content of 30% by weight or less. Also, if the water content of the mineral raw material is less than 1% by weight, it is difficult to reduce the water content to less than 1% by weight even if the drying process is performed for a long time.

(Method for measuring water content (moisture content) of mineral raw materials)
The water content of the mineral raw material can be measured, for example, by a heat drying method. Specifically, the water content can be measured by an infrared moisture meter (FD-230, manufactured by Kett Scientific Laboratory Co., Ltd.). The water content (Wi) in the present invention is obtained from the free water content (Wf), which indicates the content of water removed by evaporation under general drying conditions, and the equilibrium water content (We), at which drying does not proceed any further. It is a value calculated and represented by the following formula (I).
(Formula I) Wi=Wf+We
A method for measuring the moisture content is not particularly limited, and a method generally used for measuring the moisture content can be used. For example, the moisture content of coal and coke can be measured according to JIS M8812. Moreover, the moisture content of iron ore, limestone, and sintered ore can be measured according to JIS M8705. Then, the water content of the mineral raw material can be calculated from the water content obtained by measurement.

The polymer dispersant used in the method of the present invention disperses the water contained in the mineral raw material, and the particle size of 95% by weight or more of the polymer dispersant after contact with the mineral raw material is the same as the polymer dispersion before contact. It is not particularly limited as long as it is 110% or more and less than 500% of the average particle size of the agent.
95% by weight or more of the particle size of the polymer dispersant after contacting with the mineral raw material (i.e., after the contacting step in the present invention) is equal to that of the polymer dispersing agent before contacting with the mineral raw material (i.e., before the contacting step in the present invention). If it is 110% or less of the average particle size of , the water retention capacity of the polymer dispersant dispersed in contact with the mineral raw material is low, and there is a possibility that heat generation due to oxidation of the mineral raw material cannot be sufficiently suppressed.
In addition, 95% by weight or more of the particle size of the polymer dispersant after contacting with the mineral raw material (i.e., after the contacting step in the present invention) is the polymer before contacting with the mineral raw material (i.e., before the contacting step in the present invention). When the average particle size of the dispersant is 500% or more, the water retention capacity of the polymer dispersant dispersed in contact with the mineral raw material increases, the dispersant becomes easily deformed, and the particles stably retain moisture due to flow. Dispersion may not be possible. In addition, even if the stickiness is suppressed by suppressing the water content of the mineral raw material, if the water retention amount of the polymer dispersant in contact with the polymer dispersant is increased and the stickiness is obtained, the equipment such as the hopper of the mineral raw material will be clogged. It can lead to sticking to belt conveyors, which can lead to poor handling, safety and equipment efficiency.
The polymer dispersant used in the method of the present invention disperses the water contained in the mineral raw material, and after contact with the mineral raw material (after the contacting step), the particle size of the polymer dispersant is 95% by weight or more. It is preferably 115% or more and less than 500%, more preferably 120% or more and less than 500%, of the average particle size of the polymer dispersant before (before the contact step).
The polymer dispersant used in the method of the present invention disperses the water contained in the mineral raw material, and after contact with the mineral raw material (after the contacting step), the particle size of the polymer dispersant is 95% by weight or more. It is preferably 110% or more and less than 450%, more preferably 110% or more and less than 420%, and 110% or more and less than 400% of the average particle size of the polymer dispersant before (before the contact step). is more preferable.
In the present invention, the preferred lower limit and preferred upper limit of the average particle size of the polymer dispersant after the contacting step can be appropriately combined.

Polymeric dispersants include, for example, polyacrylic acid (salt), polyacrylic acid ester, polyacrylamide, polymethacrylic acid (salt), polymethacrylic acid ester, polyalkyleneimine, polyoxyalkylene, polymaleic acid, monomers thereof and copolymers of these monomers and other monomers.

Polyacrylic acid (salt) monomers include acrylic acid, sodium acrylate, potassium acrylate, ammonium acrylate, etc.; polyacrylic acid ester monomers include methyl acrylate, ethyl acrylate, acrylic acid n -propyl, n-butyl acrylate, isobutyl acrylate, hydroxyethyl acrylate, 2-ethylhexyl acrylate, etc.; monomers of polymethacrylic acid (salts) such as methacrylic acid, sodium methacrylate, etc.; polymethacrylic acid Ester monomers include methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, hydroxyethyl methacrylate, 2-ethylhexyl methacrylate, etc.; polyalkyleneimine monomers Examples include ethyleneimine, methylethyleneimine, etc.; examples of polyoxyalkylene monomers include ethylene oxide, etc.; examples of other monomers include vinylsulfonic acid, styrenesulfonic acid, acrylamide, methacrylamide, N-ethyl (meth ) acrylamide, vinylpyridine and the like.

The polymer dispersant is preferably at least one selected from the group consisting of polyacrylic acid, sodium polyacrylate, calcium polyacrylate and ammonium polyacrylate, and sodium polyacrylate and/or Or polyacrylic acid ammonium salt is more preferable.
Polymer dispersants may be used alone or in combination of two or more.

The amount of polymer dispersant to be added is not particularly limited, but for example, it is preferably 0.02 parts by weight or more and 1 part by weight or less with respect to 100 parts by weight of the mineral raw material. If the amount of the polymer dispersant is less than 0.02 parts by weight with respect to 100 parts by mass of the mineral raw material, the water content of the mineral raw material does not become 10% by weight or less, and the mineral raw material having a high water content cannot be used in equipment. Adhesion may occur and equipment failure may not be suppressed. In addition, when the amount of the polymer dispersant is more than 1 part by weight with respect to 100 parts by weight of the mineral raw material, the polymer dispersant is excessively present, which increases impurities in the mineral raw material, and is cost effective. It is not preferable from the aspect of
The lower limit of the amount of polymer dispersant to be added is preferably 0.02 parts by weight, more preferably 0.025 parts by weight, per 100 parts by weight of the mineral raw material.
The upper limit of the amount of the polymer dispersant to be added is preferably 1 part by weight, more preferably 0.8 part by weight, and 0.06 part by weight with respect to 100 parts by weight of the mineral raw material. It is even more preferable to have In the present invention, the preferred lower limit and preferred upper limit of the amount of the polymeric dispersant described above can be combined as appropriate.
The amount of polymer dispersant to be added may be determined according to the moisture content of the mineral raw material. Since the moisture content of mineral raw materials changes depending on the number of days after precipitation or watering, and the humidity of the storage environment, it is possible to determine the amount of polymer dispersant to be added according to the measured moisture content of mineral raw materials. preferable.

In the method of the present invention, a mineral raw material having a water content of 1 to 30% by weight and containing 70% by weight or more of particles having a particle diameter of 8 mm or less is brought into contact with the above-described polymer dispersant to obtain a dispersant-containing mineral raw material. so that the water content of 95% by weight or more of the dispersant-containing mineral raw material (mineral raw material containing a polymer dispersant) after the contacting step is 1 to 12% by weight. The raw material and the polymer dispersant are brought into contact with each other.
The water content of the dispersant-containing mineral raw material after the contacting step is 1 to 12% by weight, thereby suppressing natural oxidation and heat generation during transportation and storage of the mineral raw material, and during transportation and storage. It is possible to improve the handleability of.
From the viewpoint of further suppressing natural oxidation and heat generation during transportation and storage of the mineral raw material, the water content of the dispersant-containing mineral raw material after the contacting step is preferably 3% or more, and is 5% or more. is more preferable.
Further, from the viewpoint of further improving the handling properties of the mineral raw material during transportation and storage, the water content of the dispersant-containing mineral raw material after the contacting step is preferably 11% or less, more preferably 10% or less. more preferred.
In the present invention, the preferred lower limit and preferred upper limit of the moisture content of the dispersant-containing mineral raw material after the contacting step can be combined as appropriate.

The polymeric dispersant used in the method of the present invention preferably has an average particle size of 5 to 1400 μm. By bringing a polymer dispersant having an average particle size of 5 to 1400 μm into contact with a mineral raw material containing 70% or more of particles having a particle size of 8 mm or less, the water content of the mineral raw material can be effectively reduced, and natural oxidation can be performed. This is because sufficient effects can be obtained for heat generation suppression.
When the average particle size of the polymer dispersant is smaller than 5 µm, the dispersibility of the water contained in the mineral raw material is improved. The specific surface area increases, and evaporation from the surface of the polymer dispersant may result in insufficient retention of moisture. Therefore, there is a possibility that the expected effects of suppressing natural oxidation and heat generation cannot be sufficiently obtained.
Further, when the average particle size of the polymer dispersant is larger than 1400 μm, the water absorption of the polymer dispersant is large and the water retention capacity is high. dispersibility becomes worse. Therefore, there is a possibility that expected uniform spontaneous oxidation and heat generation suppressing effect cannot be sufficiently obtained.
The average particle size of the polymeric dispersant is the volume average particle size determined by a sieving method, and can be measured using a measuring method according to JIS 8815, for example.
More preferably, the polymer dispersant used in the method of the present invention has an average particle size of 150 μm or more. Moreover, it is more preferable that the average particle diameter is 900 μm or less. In the present invention, the preferred lower limit and preferred upper limit of the average particle size of the polymeric dispersant can be combined as appropriate.

In the method of the present invention, the equipment failure caused by the mineral raw material is at least one selected from the group consisting of spontaneous ignition of the mineral raw material, root clogging during transportation and storage, and adhesion of the mineral raw material to the equipment. Preferably.
The facility in the present invention refers to, for example, a facility in a transfer line that feeds mineral raw materials in a predetermined line from a mining and ore processing site, through a storage location for mineral raw materials such as a raw material yard, to a facility that uses mineral raw materials. , holds, trucks, wagon beds, raw material yards, pipes, belt conveyors, belt conveyor joints, conveyor chains, chutes, hoppers, silos, blending tanks, pulverizers, moisture conditioning equipment, coal charging vehicles, etc. Note that here, chutes, hoppers, silos, etc., which have a function of temporary storage are also included.

In the method of the present invention, a mineral raw material having a water content of 1 to 30% by weight and containing 70% by weight or more of particles having a particle diameter of 8 mm or less is brought into contact with a polymer dispersant to obtain a dispersant-containing mineral raw material. The process may be located in any of the facilities in the present invention described above and the transfer line connecting one facility and another facility, and is not particularly limited, but is a storage place for mineral raw materials, mineral raw materials It is preferable that the polymeric dispersant and the mineral raw material are brought into contact with each other on the transfer line from the storage location of . As a result, the mineral raw material and the polymeric dispersant are mixed each time the transfer line such as a belt conveyor is transferred, and the polymeric dispersant can be dispersed in the mineral raw material.
When the mineral raw material and the polymer dispersant are brought into contact with each other in the place where the mineral raw material is stored or in the storage container, it is preferable to stir and mix them appropriately.

The method of bringing the polymer dispersant and the mineral raw material into contact is not particularly limited, and examples thereof include spraying, air pressure feeding, screw feeder, and the like.
In addition, the method of mixing the polymer dispersant and the mineral raw material is not particularly limited, and a method of mixing using a heavy machine, a method of mixing using the impact of a transfer section of a belt conveyor, and a mixing device such as a mixer. and the like.

In the method of the present invention, water is added to the dispersant-containing mineral raw material (mineral raw material containing a polymer dispersant) at the same time as the contacting step or after the contacting step. 95% by weight or more of the polymer dispersant has a particle size of 110% or more and less than 500% of the average particle size of the polymer dispersant before the contacting step, and 95% by weight or more of the dispersant-containing mineral after the contacting step. A water content adjustment step of adjusting the water content so that the raw material has a water content of 1 to 12% by weight may be included.
In addition, in the moisture adjustment step, water is preferably added to the dispersant-containing mineral raw material so that the particle size of the polymer dispersant, which accounts for 95% by weight or more after the contact step, becomes 115% or more, and preferably 200% or more. It is more preferable to add water so that
In addition, in the moisture adjustment step, water is added to the dispersant-containing mineral raw material so that the water content of the dispersant-containing mineral raw material of 95% by weight or more after the contacting step becomes 3% or more, preferably 5%. It is more preferable to add water so as to achieve the above.
In addition, the water content adjustment step can adjust the water content within a range in which the preferred lower limit and the preferred upper limit are appropriately combined.
The moisture adjustment step may be performed one or more times in the method for suppressing equipment failure of the present invention. It is preferably carried out in facilities such as chutes, hoppers, silos, blending tanks, pulverizers, moisture conditioning facilities, and coal charging vehicles.

According to the present invention, a dispersant-containing mineral raw material in which water is kept dispersed can be obtained. The present invention is a method for producing a dispersant-containing mineral raw material containing a mineral raw material and a polymer dispersant, which contains 70% or more by weight of particles having a water content of 1 to 30% by weight and a particle diameter of 8 mm or less. A mineral raw material has a contacting step of contacting a polymer dispersant, and in the contacting step, the particle size of 95% by weight or more of the polymer dispersing agent after the contacting step is equal to that of the polymer dispersing agent before the contacting step. 110% or more and less than 500% with respect to the average particle size of the mineral raw material, and the water content of the dispersant-containing mineral raw material of 95% by weight or more after the contacting step is 1 to 12% by weight. It is also a method for producing a dispersant-containing mineral raw material, characterized by bringing it into contact with a polymer dispersant.
As mentioned above, if the water content of mineral raw materials is low, the possibility of spontaneous combustion increases, while if the water content is high, it will adhere to equipment, making it difficult to handle during storage and transportation, and It has the problem of reduced efficiency and safety. According to the production method of the present invention, the water retained in the mineral raw material is dispersed by the polymer dispersant, the water content of the mineral raw material itself is 1 to 12% by weight, and the water is retained around the mineral raw material. Since it is possible to obtain the mineral raw material in which the polymer dispersant is dispersed, it is possible to obtain the dispersant-containing mineral raw material in which heat generation due to oxidation of the mineral raw material and deterioration of handling properties due to adhesion of the mineral raw material are suppressed. .

Embodiments of the polymeric dispersant, the mineral raw material, the polymeric dispersant after the contacting step, and the dispersing agent-containing mineral raw material after the contacting step in the method for producing a dispersant-containing mineral raw material of the present invention, and preferred aspects thereof , the aspects of the polymer dispersant, the mineral raw material, the polymeric dispersant after the contacting step, and the dispersant-containing mineral raw material after the contacting step in the method for suppressing equipment failure of the present invention, and preferred aspects thereof.
In the method for producing a dispersant-containing mineral raw material of the present invention, the method and position of contact between the polymer dispersant and the mineral raw material are the same as in the method for suppressing equipment failure of the present invention.

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these.

<Test Example 1: Effectiveness Confirmation Test for Average Particle Size of Polymer Dispersant>
Regarding the polymer dispersant (purchased by Nalco_9922 from Katayama Nalco Co., Ltd.), the deformation rate was measured when the particle size when containing water was the ratio shown in Table 1 below, based on the average particle size when dry. The ratio (%) of the average particle size of the polymer dispersant is the average particle size (B) when water is evaporated by drying at 105°C for 2 hours or more, and the contact with the mineral raw material containing water increases. It was calculated by the following formula II using the average particle diameter (W).
(Formula II) Average particle size ratio (%) = W x 100/B
The deformation ratio was measured according to JIS K7181. A container was filled with 20 cc of the polymer dispersant as a preload, and a pressure of 1 kg/cm ² was applied after adjusting the measurement conditions by applying a load of 1/10 at the initial stage to eliminate voids between the particles. A compression test was performed, and the deformation ratio (strain, (L _{0 -} L) / L ₀ ) was measured. The deformation rate was converted into % and used as an index of the deformation strength of the particles. At the same time, the presence or absence of adhesion of dispersant particles to the load rod after the test was confirmed to evaluate the presence or absence of surface tackiness. Table 1 shows the results obtained.

(Nalco_9922)
Ingredients: Polyacrylic acid-based polymer Distributor: Ecolab, Inc.
Maximum water absorption: 280%
Average particle size: 99% or more are 1 mm or less

From the results in Table 1, when the ratio of the average particle size of the polymer dispersant containing water to the average particle size of the polymer dispersant in a dry state increases by 500% or more, the deformation ratio increases, and the polymer dispersant increases. It was confirmed that tackiness was generated by softening and gelation was progressing. As a result, it has been found that the fluidity of the polymer dispersant is improved, the dispersant tends to be biased, the water cannot be stably retained, and a sufficient effect as a dispersant cannot be exhibited.

<Example 1: Temperature rise suppression effect test using sub-bituminous coal powder>
200 g of sub-bituminous coal from a certain ironworks having a particle size distribution shown in Table 2 below was dried with warm air for 2 hours, and then the initial moisture content was measured, placed in a container with a capacity of 350 cc, and shown in Table 3 below. A polymer dispersant (Nalco_9922) and water, or only water was added to obtain a water content, and sub-bituminous coal A to each of Examples 1-1 and 1-2 and Comparative Examples 1-1 to 1-4 were prepared. got F. Next, the obtained sub-bituminous coals A to F were heated under the following conditions, and the time (h) for the sub-bituminous coals to reach 150° C. and 200° C. by heating was measured.
(Heating conditions)
For temperature measurement inside the sample, three thermocouples are placed in the container. , one was placed in the middle of the height of the sample, 0.5 cm inside from the side of the container for the temperature measurement of the inner surface of the sample. Next, the container was heated from the outside using an infrared heater adapted to the size of the container. The temperature during heating is controlled by measuring the internal temperature and inner surface temperature of the sample using thermocouples installed at the center and inner surface of the sample in the container, and measuring the temperature of the inner surface of the sample. Due to the increase in the average temperature of the pair, the heater is turned on when the temperature of the inner surface of the sample has a temperature difference of 10°C with respect to the internal center temperature of the sample, and turned off when the temperature difference is 20°C. The heating temperature was adjusted so that the inner surface temperature was 10 to 20° C. higher than the internal center temperature. Table 3 shows the time (h) for the sub-bituminous coal to reach 150° C. and 200° C. by heating. The initial moisture content of the sub-bituminous coal after being dried with warm air for 2 hours was 3%.

From the results in Table 3 above, sub-bituminous coals A and B, which required 30 hours or more to reach 150° C., had average particle size ratios of 118% and 129% of the polymer dispersants used.
From the result of sub-bituminous coal C, which took 5.8 hours to reach 150 ° C., the ratio of the average particle size of the polymer dispersant used after retaining moisture was the average particle size of the polymer dispersant when dried ( When it is less than 110% of the average particle size of the polymer dispersant before contact with subbituminous coal), the time to reach 150 ° C. is as short as 5.8 hours, and the heat generation suppressing effect can be sufficiently obtained. I confirmed that it is not possible. (Comparative Example 1-1).
Further, from the results of Comparative Examples 1-2 and 1-3, sub-bituminous coals D and E, to which no polymer dispersant was added, even when the moisture content of the sub-bituminous coal was 7% and 11%, were in a wet state. The time required to reach 150° C. was short, and a sufficient heat generation suppressing effect could not be obtained.

<Example 2: Temperature rise suppression effect test using dust containing iron oxide>
Dust components of converter gas having particle size distribution shown in Table 4 below (Fe; 50%, iron oxides (FeO, Fe ₂ O ₃ ); 40%, other components (Ca, Si, Mn, Mg, etc.; 10 %)) was dried with warm air for 2 hours, and then the initial moisture content was measured. Water or only water was added to obtain dusts G to K according to Examples 2-1 and 2-2 and Comparative Examples 2-1 to 2-3.
A temperature rise suppression effect test was conducted under the same conditions as in Example 1 except that dusts G to K were used instead of subbituminous coals A to F, and the time required for the dust to reach 150 ° C. and 200 ° C. by heating. (h) was measured. The results obtained are shown in Table 5 below. The initial moisture content of the dust after drying with warm air for 2 hours was 2.5%.

From the results in Table 5 above, for Dusts G and H, which required 12 hours or more to reach 150°C, the ratio of the average particle size after retaining moisture of the polymer dispersant used was They were 116% and 124% of the average particle size of the agent (average particle size of the polymeric dispersant before contact with dust).
On the other hand, when the polymer dispersant was not used, the time required to reach 150 ° C. was within 3 hours even when the moisture content of the dust was 6% and 10% in a wet state (Comparative Example 2- 1-2-3).

From the results of Test Example 1 above, when the ratio of the average particle size of the polymer dispersant after contact with the mineral raw material is 500% or more with respect to the average particle size of the polymer dispersant before contact, the polymer dispersion It was confirmed that tackiness was caused by deformation of the agent.
Further, from the results of Examples 1 and 2, a mineral raw material having a water content of 1 to 30% by weight and containing 70% by weight or more of particles having a particle diameter of 8 mm or less is brought into contact with a polymer dispersant. It was confirmed that heat generation of the mineral raw material can be effectively suppressed by setting the average particle size of the polymer dispersant after contact to be 110% or more of the average particle size of the polymer dispersant before contact.
That is, from the results of Test Example 1, Examples 1 and 2, a mineral raw material having a water content of 1 to 30% by weight and containing 70% by weight or more of particles having a particle diameter of 8 mm or less is brought into contact with a polymer dispersant. , a contacting step for obtaining a dispersant-containing mineral raw material, and in the contacting step, the particle size of 95% by weight or more of the polymer dispersant after the contacting step is greater than the average particle size of the polymer dispersing agent before the contacting step. , 110% or more and less than 500%, and the water content of 95% by weight or more of the dispersant-containing mineral raw material after the contacting step is 1 to 12% by weight. It was confirmed that heat generation and adhesion of mineral raw materials were suppressed by increasing the temperature.

Claims (4)

A method for suppressing equipment failure caused by mineral raw materials,
a contacting step of contacting a mineral raw material having a water content of 1 to 30% by weight and containing 70% by weight or more of particles having a particle diameter of 8 mm or less with a polymer dispersant to obtain a dispersant-containing mineral raw material;
In the contact step, the particle size of 95% by weight or more of the polymer dispersant after the contact step is 110% or more and less than 500% of the average particle size of the polymer dispersant before the contact step, and the contact A method for suppressing equipment failure, comprising contacting the mineral raw material with the polymer dispersant so that the dispersant-containing mineral raw material having a water content of 95% by weight or more after the process has a water content of 1 to 12% by weight. . 2. The method for suppressing equipment failure according to claim 1, wherein the polymer dispersant has an average particle size of 5 to 1400 μm before the contacting step. 2. The equipment failure caused by the mineral raw material is at least one selected from the group consisting of spontaneous ignition of the mineral raw material, root clogging during transportation and storage, and adhesion of the mineral raw material to the equipment. Equipment failure suppression method described. 4. The equipment failure suppression method according to claim 1, 2 or 3, wherein the mineral raw material is at least one selected from the group consisting of coal, iron, coke and iron oxide.