JP6825738B1 - How to prevent adhesion and clogging of mineral raw materials - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for efficiently and stably improving the adhesiveness of a raw material mixture and the transportability of a mineral raw material to prevent the raw material mixture from adhering to a transfer processing facility and clogging (blocking) of the transfer processing facility. .. SOLUTION: A raw material mixture in which a mineral raw material is brought into contact with a water-absorbent resin conforming to the following criteria is transferred or treated in a transfer processing facility to prevent adhesion and clogging of the mineral raw material in the transfer processing facility. According to the standard, water having the same mass as that of the water-absorbent resin is added to the water-absorbent resin, and after 10 minutes, the water-absorbent sample is placed on a vibrating sieve having an opening of 9.5 mm and a frequency of 2800 rpm for 1 minute. A method for preventing adhesion and clogging of mineral raw materials, wherein a vibrating sieve test is performed, the residual rate of a water-absorbing sample on the vibrating sieve is determined by the following formula (1), and the residual rate is 50% by mass or less. Residual rate (% by mass) = (mass of water-absorbing sample on the vibrating sieve after the vibrating sieve test) ÷ (mass of water-absorbing sample on the vibrating sieve before the vibrating sieve test) × 100 ... (1) [Selection diagram] None

Description

The present invention relates to a method for preventing adhesion and clogging of a mineral raw material, and more particularly to a method for preventing adhesion and clogging of a wet mineral raw material in a transfer processing facility.

When the iron-making raw materials are transported to the steelworks by a bulk cargo ship, the water accumulated on the floor of the hold puts the iron-making raw materials under the aggregate into a slurry state. Further, even when the ore raw material and the raw material dust are stored in the raw material yard in the open state, they may be in a slurry state due to water such as rain or watering to prevent dust.
Since the mineral raw material slurry such as the steelmaking raw material in such a slurry state is a muddy fluid having a large amount of water, there is a problem that it is difficult to carry it out from the shipyard or the raw material yard.

In response to such a problem, the present inventor brought a polymer absorbent into contact with the iron-making raw material slurry to form a solidified steel-making raw material slurry, which did not require labor such as draining and improved handling. A method is proposed (see Patent Document 1).

On the other hand, the mineral raw materials that have been carried into steelworks, thermal power plants, etc. and are piled up in the raw material yard are further transferred from the raw material yard to the equipment that uses the mineral raw materials by connecting the belt conveyor. For example, when supplying coal to a boiler of a thermal power plant, the coal is generally transferred to the boiler in a series of lines after connecting to a belt conveyor and then passing through a coal crusher and a bucket type conveyor.
Since the raw material yard and conveyor belt equipment are outdoors, the coal is exposed to rain and becomes wet. Even if the coal is not in the slurry state as described above, the wet coal tends to adhere to the contact surface of the transfer processing equipment such as the pipe (coal supply pipe) for supplying the coal to the boiler, the belt conveyor, the chute, and the hopper. Furthermore, it may stick and the piping etc. may be clogged (blocked).

When such adhesion or clogging (blockage) occurs, conventionally, the operation of the line is stopped, the jammed coal is taken out, or the transfer processing equipment is disassembled to eliminate the adhesion or clogging (blockage). In addition, the efficiency of coal transfer has decreased, and the efficiency of power generation at thermal power plants has also decreased.

In response to such problems, the present inventor contact-mixes a water-absorbent resin with a target mineral raw material to reduce the fluidity and adhesiveness of water by absorbing water on the surface of the mineral raw material to improve transportability. We are proposing an improved transport method (see Patent Document 2).

Japanese Unexamined Patent Publication No. 2013-256710 JP-A-2018-58017

However, in the transport method described in Patent Document 2, depending on the type of the water-absorbent resin used, if the water-absorbent resin contains even a small amount of water, it becomes lumpy and adheres to the equipment, increasing the risk of clogging (blocking). It was. In addition, when the water-absorbent resin becomes lumpy, the reaction with the entire mineral raw material becomes insufficient, and a sufficient modification effect may not be obtained.

On the other hand, in the present invention, when the mineral raw material is transferred or processed, the raw material mixture, which is a mixture of the mineral raw material and the water-absorbent resin, adheres to the transfer processing equipment and the transfer processing equipment is clogged (blocked). It was made to solve the problem of minerals.
That is, the present invention is a method for efficiently and stably improving the adhesiveness of a raw material mixture and the transportability of a mineral raw material to prevent the raw material mixture from adhering to a transfer processing facility and clogging (blocking) of the transfer processing facility. The purpose is to provide.

In the present invention, by using a water-absorbent resin that does not easily become lumpy (the water-absorbent resins after water absorption do not easily adhere to each other), the water-absorbent resin adheres to the transfer treatment equipment or clogs the transfer treatment equipment (blockage). It is based on the finding that the risk is reduced and that the water-absorbent resin sufficiently absorbs water in the entire mineral raw material to obtain a sufficient modification effect.

That is, the present invention provides the following [1] to [4].
[1] A method of transferring or treating a raw material mixture in which a mineral raw material is brought into contact with a water-absorbent resin conforming to the following criteria in a transfer processing facility to prevent adhesion and clogging of the mineral raw material in the transfer processing facility. The standard is that water of the same mass as that of the water-absorbent resin is added to the water-absorbent resin, and after 10 minutes have passed, the water-absorbent sample is subjected to a vibration sieve having an opening of 9.5 mm and a frequency of 2800 rpm for 1 minute. A method for preventing adhesion and clogging of mineral raw materials, wherein a sieving test is performed, the residual rate of a water-absorbing sample on the vibrating sieve is determined by the following formula (1), and the residual rate is 50% by mass or less.
Residual rate (% by mass) = (mass of water-absorbing sample on the vibrating sieve after the vibrating sieve test) ÷ (mass of water-absorbing sample on the vibrating sieve before the vibrating sieve test) × 100 ... (1)
[2] The transfer processing equipment includes a shipyard, unloader, stacker, raw material yard, reclaimer, piping, belt conveyor, belt conveyor transit part, conveyor chain, chute, hopper, silo, compounding tank, crusher, and humidity control coal equipment. , And the method for preventing adhesion and clogging of mineral raw materials according to the above [1], which is at least one of a coal loading vehicle.
[3] The above-mentioned [1] or [2], which comprises a step of obtaining the raw material mixture by spraying the water-absorbent resin on a mineral raw material before or during the transfer in the transfer processing facility. How to prevent adhesion and clogging of mineral raw materials.
[4] The mineral according to any one of the above [1] to [3], which comprises a step of obtaining the raw material mixture by adding the water-absorbent resin into a container containing a mineral raw material and stirring and mixing the mixture. Method of preventing adhesion and clogging of raw materials.

According to the present invention, the adhesiveness of the raw material mixture and the transportability of the mineral raw material are efficiently and stably improved to prevent the raw material mixture from adhering to the transfer processing equipment and clogging (blocking) of the transfer processing equipment. Can be done.
Therefore, the method of the present invention can contribute to the efficient transfer or treatment of mineral raw materials.

Hereinafter, the method for preventing adhesion and clogging of the mineral raw material of the present invention will be described.
The term "adhesion prevention" in the present invention includes not only the case where the mineral material does not adhere at all, but also the case where the adhesion is sufficiently suppressed to the extent that the transfer of the mineral raw material is not hindered even when the mineral material adheres partially. It shall be used in a meaning.

In the method for preventing adhesion and clogging of a mineral raw material of the present invention, a mineral raw material, particularly a raw material mixture in which a wet mineral raw material is brought into contact with a water-absorbent resin satisfying a predetermined standard is transferred or treated by a transfer processing facility, and the mineral is described. This is to prevent adhesion and clogging (blockage) of raw materials in the transfer processing equipment.
The surface of the mineral raw material is modified by contact with a water-absorbent resin that meets a predetermined standard. As a result, the adhesion of the mineral raw material to the contact surface of the transfer processing equipment is suppressed, the slipperiness is improved, and the mineral raw material can be prevented from adhering or being clogged (blocked) in the transfer processing equipment. it can.

(Mineral raw material)
The type of mineral raw material is not particularly limited, and examples thereof include coal, iron ore, dust, coke, and limestone. These may be one kind alone or a mixture of two or more kinds.
The shape, size, etc. of the mineral raw material are not particularly limited, but since the present invention is a method for preventing clogging (clogging), a form that is easily clogged, for example, one particle. It is preferably applied to particles having a particle size of 2 mm or less, such as granules and powders. Here, the particle size of the mineral atom is the particle size measured by using the JIS Z 8815 sieving test method (dry sieving method).

The term "wet mineral raw material" as used herein refers to a mineral raw material that is not in a slurry state but contains water and can be conveyed as a solid substance by a belt conveyor. That is, it is distinguished from a slurry which is a muddy or liquid fluid having a large amount of water, which is difficult to convey by a belt conveyor. The water content (moisture content) in the wet mineral raw material varies depending on the type and properties of the mineral raw material and cannot be unconditionally determined. For example, in the case of coal, the water content is about 1 to 30 mass. When it is%, it can be said that it is in a wet state, and when it exceeds about 30% by mass, it can be said that it is in a slurry state.
The water content in the mineral raw material is not particularly limited in its origin, and may be derived from the raw material itself, or may be water such as water sprinkled to prevent rain or dust that comes into contact during transportation or storage. Good.

(Water-absorbent resin)
The water-absorbent resin is defined in JIS K7223 (1996) and JIS K7224 (1996) as "a resin that highly absorbs and swells water, and is a hydrophilic substance having a crosslinked structure that absorbs water by coming into contact with water. It has the characteristic that once it absorbs water, it does not easily separate even when pressure is applied. " That is, it is a resin having a large amount of water absorption and excellent water retention.

The type of the water-absorbent resin may be either a synthetic resin type or a natural product-derived type, and is not particularly limited. For example, poly (meth) acrylic acid, poly (meth) acrylate, and poly (meth). Examples thereof include acrylic acid esters, poly (meth) acrylamides, polyalkyleneimines, polyoxyalkylenes, polymaleic acids, and copolymers containing any of the monomers constituting them. In the present invention, "(meth) acrylic" means acrylic or methacrylic.

Examples of the monomer constituting the poly (meth) acrylate salt include sodium (meth) acrylate, potassium (meth) acrylate, and ammonium (meth) acrylate.
Examples of the monomers constituting the poly (meth) acrylic acid ester include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, and (meth). ) Isobutyl acrylate, hydroxyethyl (meth) acrylate, -2-ethylhexyl (meth) acrylate and the like.
Examples of the monomer constituting the polyalkyleneimine include ethyleneimine and methylethyleneimine.
Examples of the monomer constituting the polyoxyalkylene include ethylene oxide and propylene oxide.
Examples of other monomers constituting the copolymer include vinyl sulfonic acid, styrene sulfonic acid, N-ethyl (meth) acrylamide, vinyl pyridine and the like.

The water-absorbent resin may be used alone or in combination of two or more. From the viewpoint of availability and high water absorption, polyacrylic acid or sodium polyacrylate is preferably used, and sodium polyacrylate is particularly preferable.
Further, the water-absorbent resin may be used in combination with another water-absorbing agent. Examples of other water-absorbing agents include water-absorbing agents that do not easily agglomerate, such as silica gel, zeolite, and activated carbon. Further, as the concentration of the other water absorbing agent, the water absorbing resin is selected so as to satisfy the selection criteria described later even if the other water absorbing agent is used in combination.
The properties of the water-absorbent resin are preferably granular or powdery having a particle size equal to or smaller than that of the mineral raw material from the viewpoint of uniform contact with the surface of the mineral raw material and ease of handling.

The amount of the water-absorbent resin to be brought into contact with the mineral raw material is appropriately adjusted according to the type and properties of the mineral raw material and the water-absorbent resin, but the surface of the mineral raw material surface without impairing the desired physical properties in the use of the mineral raw material. From the viewpoint of sufficiently reducing the water content and from the viewpoint of cost and the like, for example, in the case of coal, 0.001 is obtained with respect to 100 parts by mass of wet coal (coal having a water content of 1 to 30% by mass). It is preferably ~ 5 parts by mass, more preferably 0.005 to 1 part by mass, and even more preferably 0.01 to 0.5 parts by mass.

In the present invention, a water-absorbent resin that does not easily become lumpy is selected based on the following criteria. The standard is a vibrating sieve test in which water having the same mass as that of the water-absorbent resin is added to the water-absorbent resin, and after 10 minutes have passed, the water-absorbent sample is placed on a vibrating sieve having a mesh size of 9.5 mm and a frequency of 2800 rpm for 1 minute. Is performed, and the residual ratio (mass%) of the water-absorbing sample on the vibrating sieve is calculated by the following formula (1). Then, a water-absorbent resin having a residual ratio of 50% by mass or less, preferably 40% by mass or less is selected.
Residual rate (% by mass) = (mass of water-absorbing sample on vibrating sieve after vibrating sieve test) ÷ (mass of water-absorbing sample (total water-absorbing sample) on vibrating sieve before vibrating sieve test) × 100 ... (1) )

The method for producing the water-absorbent resin having a residual ratio of 50% by mass or more is not particularly limited, and examples thereof include a reverse phase suspension polymerization method and an aqueous solution polymerization method.
In the reverse phase suspension polymerization method, a monomer mixture containing a monomer such as acrylic acid and sodium acrylate and an aqueous solution containing a polymerization catalyst, a cross-linking agent, etc. are suspended by a dispersant in an organic solvent (hexane, toluene, etc.). It is a method of polymerizing at a constant temperature (for example, 60 to 80 ° C.). After the polymerization, the organic solvent is removed by centrifugal dehydration or the like, and the water content is further removed by a dryer or the like to obtain a pearl-like water-absorbent resin.
On the other hand, the aqueous solution polymerization method is continuous with an adiabatic polymerization method in which water is used as a solvent and a mixed solution containing a monomer such as acrylic acid or sodium acrylate; a polymerization catalyst; a cross-linking agent or the like is used to polymerize in a reaction vessel. There is a belt-type polymerization method in which the mixed solution is polymerized on a moving belt conveyor. The polymer obtained by the aqueous solution polymerization method is dried, water is removed, and then pulverized (crushed) to adjust the particle size distribution.
In either the reverse phase suspension polymerization method or the aqueous solution polymerization method, surface cross-linking is preferable in order to prevent the water-absorbent resin from agglomerating after absorbing water. Here, "surface cross-linking" means "cross-linking molecular chains near the surface of the water-absorbent resin to increase the cross-linking density of the surface layer". The surface-crosslinked water-absorbent resin can be obtained, for example, by adding a cross-linking agent such as a polyhydric alcohol.

(Transfer processing equipment)
The transfer processing equipment referred to in the present invention refers to equipment in a transfer line that feeds mineral raw materials on a predetermined line, for example, from a shipyard to equipment that uses mineral raw materials through a storage place for mineral raw materials such as a raw material yard. , Funakura, unloader, stacker, raw material yard, reclaimer, piping, belt conveyor, belt conveyor transit part, conveyor chain, chute, hopper, silo, compounding tank, crusher, humidity control coal equipment, coal loading car, etc. Here, those having a function of temporarily storing such as a chute, a hopper, and a silo are also included. It is distinguished from transportation by ship or truck, transportation by bucket, etc.
The present invention provides good adhesion and good adhesion in transfer processing equipment, particularly in places where inconveniences are likely to occur due to adhesion and clogging (blockage), specifically, in piping, belt conveyors, conveyor chains, chutes, hoppers, silos, etc. The effect of preventing clogging (blockage) can be obtained.
Mineral raw materials are prone to adhesion and clogging (blockage) in these transfer processing facilities, and if they are clogged, it is necessary to stop the operation of the line and then clear the clogging (blockage), which is troublesome. Was required.
On the other hand, according to the present invention, the slipperiness of the mineral raw material is improved and it becomes difficult for the mineral raw material to adhere to the contact surface of the transfer processing equipment, so that the minerals in the transfer processing equipment can be used without stopping the operation of the line. It is possible to easily prevent clogging (blockage) of raw materials and improve transportability efficiently and stably.

(Raw material mixture)
The raw material mixture is a mixture of a mineral raw material and a water-absorbent resin obtained by contacting a mineral raw material with a water-absorbent resin.
When the water-absorbent resin comes into contact with the mineral raw material, at least a part of the water content in the mineral raw material is absorbed by the water-absorbent resin, the water content on the surface of the mineral raw material is reduced, and the contact of the transfer processing equipment of the mineral raw material Adhesion to the surface is suppressed and slipperiness is improved. It is sufficient that the adhesion to the contact surface of the transfer processing equipment is suppressed, and it is not necessary that the entire amount of water contained in the mineral raw material is absorbed by the water-absorbent resin.

The method of contacting the water-absorbent resin with the mineral raw material to obtain the raw material mixture is not particularly limited, but the raw material mixture in a state where the mineral raw material and the water-absorbent resin are uniformly mixed and in contact with each other. Is preferably obtained.
The position where the water-absorbent resin is brought into contact is not particularly limited, and may be any of before, during, and after the transfer of the mineral raw material by a transfer processing facility such as a belt conveyor.
For example, a raw material mixture can be obtained by spraying the water-absorbent resin on the mineral raw material before or during the transfer in a transfer processing facility such as a belt conveyor. More preferably, the water-absorbent resin is sprayed from above the mineral raw material on the mineral raw material transferred by a transfer processing facility such as a belt conveyor. As a result, the mineral raw material and the water-absorbent resin are mixed each time the transfer processing equipment such as a belt conveyor is connected, and the water-absorbent resin is uniformly adhered to the surface of the mineral raw material to obtain an overall uniform raw material mixture. Be done.
Further, the raw material mixture can also be obtained by adding the water-absorbent resin into a predetermined container containing a mineral raw material and stirring and mixing the mixture.

The method of adding the water-absorbent resin to the mineral raw material is not particularly limited, and examples thereof include spraying, air pumping, and screw feeder.
The method of mixing the water-absorbent resin and the mineral raw material is not particularly limited, and a method of mixing coal and the water-absorbent resin using a heavy machine, a method of mixing using the impact of the connecting portion of the belt conveyor, and a method of mixing. Examples thereof include a method of mixing using a mixing device such as a mixer.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to the following Examples.

(Example 1)
[Aggregation judgment test]
As a water-absorbent resin, 5.0 g of "Kuriline (registered trademark) S-250" (manufactured by Kurita Kogyo Co., Ltd .; sodium polyacrylate) was placed on a petri dish almost evenly, and pure water 5 having the same mass as the water-absorbent resin was placed in the petri dish. .0 g was added by mist blowing and allowed to absorb water for 10 minutes. The water absorption sample after water absorption is placed in an electric sieve (“ANF-30”, manufactured by Nisso Kagaku Co., Ltd.) with a sieve mesh of 9.5 mm, and the water absorption sample (total water absorption sample) on the vibration sieve before the vibration sieve test is placed. The mass (A) is measured, a vibrating sieve test is performed on a vibrating sieve (opening 9.5 mm, frequency 2800 rpm) for 1 minute, and the mass after the vibrating sieve test (water absorption sample on the vibrating sieve after the vibrating sieve test) is performed. The mass (B)) was measured, and the residual ratio (mass%) was calculated from the following formula. The residual rate (mass%) is an index for selecting whether the water-absorbing sample is easily agglomerated. The larger the residual ratio (mass%), the easier it is to agglomerate the water-absorbing sample, and the smaller the residual ratio (mass%), the less easily the water-absorbing sample is agglomerated, and the water-absorbent resin is used for the ore raw material. It shows that the reforming effect is high.
Residual rate [mass%] = B / A x 100

[Adhesion evaluation test (modification effect confirmation test)]
To 500 g of wet iron ore (adjusted to 11% by mass of water content, no particle size adjustment), 0.1% by mass of "Kuriline (registered trademark) S-250" was added, and the mixture was uniformly stirred and mixed to prepare a raw material. A mixture sample was prepared.
On the upper part of the electric sieve, instead of the vibrating sieve, a simulated hopper (input port: 140 mm × 180 mm, discharge port: 30 mm × 60 mm, inverted square pyramidal outer shape (length: 160 mm, vertical distance: 110 mm, internal surface area: 65600 mm) ^2. The adhesion evaluation test of the raw material mixture sample was carried out using a vibration test device equipped with ( ² , angle: 70 °), made of steel).
To evaluate the adhesiveness, the prepared raw material mixture sample was put into the simulated hopper of the vibration test device, and the raw material mixture sample (adhesion amount (X) in the hopper) (g) adhering to the simulated hopper after the test was measured. went.
As for the water content, the mass (C) of about 7 g of iron ore was measured, and the mass (D) after drying this in a dryer at 105 ° C. for 2 hours was measured, and the weight was reduced (C-). D) was regarded as the water content and calculated from the following formula (2).
Moisture content [mass%] = (CD) / C × 100 ... (2)

(Example 2 and Comparative Examples 1 to 3)
In Example 1, instead of using "Kuriline (registered trademark) S-250" (manufactured by Kurita Kogyo Co., Ltd .; sodium polyacrylate) as the water-absorbent resin, "Kuriline (registered trademark) S-260 (Kurita Kogyo)" was used. "Manufactured by Sanyo Kasei Kogyo Co., Ltd .: Sodium polyacrylate) (Example 2)", "Sunfresh (registered trademark) OK-100 (Manufactured by Sanyo Kasei Kogyo Co., Ltd .: Cross-linked product of partial sodium salt of acrylic acid polymer) (Comparative Example 1)" , "CL-SA4 (SNF Co., Ltd .: sodium polyacrylate) (Comparative Example 2)", "CL-SA5 (SNF Co., Ltd .: sodium polyacrylate) (Comparative Example 3)" The agglomeration determination test and the adhesion evaluation test (modification effect confirmation test) were carried out in the same manner as in Example 1 except that the above was used.

(Comparative Example 4)
An agglomeration determination test and an adhesion evaluation test (modification effect confirmation test) were carried out in the same manner as in Example 1 except that the water-absorbent resin was not used in Example 1.

The results of each of the above Examples and Comparative Examples are summarized in Table 1.

As can be seen from the results shown in Table 1, in Examples 1 and 2 using the water-absorbent resin having a residual ratio of 50% by mass or less determined by the vibrating sieve test, the residual ratio determined by the vibrating sieve test was 50% by mass. It was confirmed that the mass (adhesion amount in the hopper) of the raw material mixture sample adhering to the simulated hopper was reduced as compared with Comparative Examples 1 to 3 using the water-absorbent resin exceeding%.
As described above, by using the water-absorbent resin having a residual ratio of 50% by mass or less determined by the vibrating sieve test, the adhesion of the raw material mixture to the contact surface of the transfer processing equipment is suppressed, the slipperiness is improved, and the adhesion and adhesion are suppressed. It can be said that it is possible to prevent clogging (blockage).

Claims (4)

A method of transferring or treating a raw material mixture in which a water-absorbent resin conforming to the following criteria is brought into contact with a mineral raw material in a transfer processing facility to prevent adhesion and clogging of the mineral raw material in the transfer processing facility.
The standard is a vibrating sieve test in which water having the same mass as that of the water-absorbent resin is added to the water-absorbent resin, and after 10 minutes have passed, the water-absorbent sample is placed on a vibrating sieve having a mesh size of 9.5 mm and a frequency of 2800 rpm for 1 minute. The method for preventing adhesion and clogging of mineral raw materials, wherein the residual rate of the water-absorbing sample on the vibrating sieve is determined by the following formula (1), and the residual rate is 50% by mass or less.
Residual rate (% by mass) = (mass of water-absorbing sample on the vibrating sieve after the vibrating sieve test) ÷ (mass of water-absorbing sample on the vibrating sieve before the vibrating sieve test) × 100 ... (1) The transfer processing equipment includes a shipyard, unloader, stacker, raw material yard, reclaimer, piping, belt conveyor, belt conveyor transfer part, conveyor chain, chute, hopper, silo, compounding tank, crusher, humidity control coal equipment, and equipment. The method for preventing adhesion and clogging of a mineral raw material according to claim 1, which is at least one of the reclaimers. The adhesion of the mineral raw material according to claim 1 or 2, which comprises a step of obtaining the raw material mixture by spraying the water-absorbent resin on the mineral raw material before or during the transfer in the transfer processing facility. How to prevent clogging. The adhesion of the mineral raw material according to any one of claims 1 to 3, which comprises a step of obtaining the raw material mixture by adding the water-absorbent resin into a container containing a mineral raw material and stirring and mixing the mixture. How to prevent clogging.