JP7390652B2 - Method for preparing objects to be processed, method and apparatus for processing powder and granular materials - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method and apparatus for processing powdery materials such as soil contaminated with radioactive substances.

Due to the Fukushima Daiichi Nuclear Power Plant accident triggered by the Great East Japan Earthquake, the scattering of radioactive materials (particularly radioactive cesium, hereinafter referred to as radioactive Cs) into areas surrounding the nuclear power plant caused serious environmental problems. Radioactive Cs released from nuclear power plants is deposited in the soil by rainfall, and it takes the form of (I) ion adsorption on humic substances and soil particle surfaces, or (II) trapped inside 2:1 type clay. In recent years, most of the radioactive Cs in adsorption form (I) has been stabilized as form (II), and contaminated soil from temporary storage sites (approximately 22 million tons, of which 2/3 is agricultural soil) is being transferred to interim storage facilities. It is considered unrealistic to bring all of the soil into the soil, and there is an urgent need to develop volume reduction technology that can be used to reduce the size of contaminated soil of type (II).

Under these circumstances, trends in the development of post-accident decontamination technology can be roughly divided into three categories. The first category is the "extraction/adsorption method" category. Recently, the proportion of the above-mentioned form (II) has increased, making it extremely difficult to extract radioactive Cs. Therefore, a technology has been developed to extract and separate dissolved Cs by disintegrating soil in a subcritical state. However, the subcritical method has problems such as not being able to obtain sufficient throughput because it is a batch method.

On the other hand, a technology that removes radioactive Cs adsorbed to soil particles along with soil fine particles is in the forefront. Among them, "microbubble flotation/classification method" is a typical example (category 2). Recently, a technology for separating soil particles in wastewater using superconducting magnetic separation has been proposed as a more advanced suspended water treatment technology. These methods require large-scale wastewater treatment downstream of the process and are unsuitable for treating agricultural soil containing a large amount of root hairs, and the latter has problems with cost and throughput.

The third category includes dry treatments such as "thermal separation" or "thermal volume reduction" treatment. For example, there is a method in which CaCl ₂ in an amount of 1/2 to the same amount as the soil is added to contaminated soil whose main component is biotite, and the soil is heated at a temperature of slightly less than 800° C. for 2 hours to separate it as Cs chloride. This method also has technical issues such as a large amount of waste.

Different from the above decontamination techniques, there is a method of classifying and decontaminating dry soil without wastewater and at room temperature (see, for example, Patent Documents 1 and 2). This method classifies contaminated soil by mixing contaminated soil and ferromagnetic powder and magnetically separating the mixture. In soil contaminated with radioactive Cs, the smaller the particle size, the higher the concentration of radioactive Cs, so it can be decontaminated by removing the contaminated soil with small particle size.

JP 2017-39123 Publication Japanese Patent Application Publication No. 2017-113744

The method described in Patent Document 1 or Patent Document 2 does not generate any additional waste including wastewater, and is considered to be a simple and excellent method, but since this method is a dry method, it generates dust. Easy measures are needed. Contaminated soil also contains wood chips, root hairs, etc., which must also be treated.

The purpose of the present invention is to provide a method and apparatus for processing powder and granular material that can be implemented at low cost with simple operations without generating excess waste, and a method for preparing a processed material that can be used in the method for processing powder and granular material. It is to provide law .

The present invention is a method for preparing a material to be processed so as to be magnetically sortable, wherein the material to be processed is a powder or granule, and divalent iron ions and trivalent iron ions coexist with the powder or granule. The divalent iron ions are provided as an aqueous solution containing divalent iron ions, and the surface of the powder is coated with a magnetic substance . This is a method for preparing a processed material, which is characterized by producing and adsorbing .

In the method for preparing a workpiece of the present invention, the trivalent iron ions are derived from iron components contained in the powder and/or are derived from chemical changes from divalent iron ions contained in the aqueous solution. It is characterized by being something.

The method for preparing a workpiece according to the present invention is characterized in that the trivalent iron ions are provided as an aqueous solution containing trivalent iron ions.

In the method for preparing a workpiece of the present invention, the aqueous solution containing divalent iron ions contains an alkaline agent, or in the method for preparing a workpiece of the present invention, the aqueous solution containing divalent iron ions The aqueous solution containing and/or trivalent iron ions is characterized by containing an alkaline agent.

In the method for preparing an object to be treated according to the present invention, the granular material contains an organic substance, the organic substance is carbonized in the heating step, and the magnetic substance is generated and adsorbed on the surface of the carbide.

In the method for preparing the object to be treated of the present invention, when the aqueous solution containing divalent iron ions and/or the aqueous solution containing trivalent iron ions, or the aqueous solution containing an alkaline agent in these is used as a chemical, the following It is characterized in that the magnetic attraction force of the magnetic substance generated and attracted to the surface of the powder or granule is controlled by controlling one or more of group (A).
(A) Divalent iron ion concentration, ratio of trivalent iron ions to divalent iron ions, type of alkali agent, concentration of alkali agent, amount of agent added, stirring intensity for the mixture of powder and granules and agent , standing time after drug addition, heating temperature, heating time, heating rate, type of anion in aqueous solution

The present invention includes a classification step of classifying the processed material obtained by the method for preparing the processed material by magnetic separation, and the powdery material is contaminated with soil, incineration ash, sludge, organic matter, a mixture thereof, or a mixture thereof. This is a method for treating powder or granular material characterized by a substance that is fixed, adsorbed, or adhered to .

The present invention provides a reaction device in which a chemical containing an aqueous solution containing at least divalent iron ions and a powder to be treated are heated in coexistence, and a magnetic substance is generated and adsorbed on the surface of the powder. and a drug supply device for supplying the drug to the reaction device; and a magnetic separator for magnetically sorting the processed material obtained through the processing material preparation device. The apparatus is characterized in that the powder and granular material is soil , incineration ash, sludge, organic matter, a mixture thereof, or a material to which pollutants are fixed, adsorbed, or adhered .

According to the present invention, there is provided a method and apparatus for processing powder and granular material that can be carried out at low cost with simple operations without generating excess waste, and a method for preparing a processed material that can be used in the method for processing powder and granular material. law can be provided.

FIG. 2 is a flow diagram illustrating a method for processing powder or granular material as an embodiment of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration diagram of a processing apparatus 1 for powder and granular material as an embodiment of the present invention. FIG. 2 is a schematic diagram illustrating the procedure for magnetic sorting performed in an example of the present invention. It is experimental data showing the relationship between the amount of FeCl ₂ .4H ₂ O added and the magnetic susceptibility increase ratio when Masago soil is used as the test soil in the powder processing method of the present invention. It is experimental data showing the relationship between the amount of FeCl ₃ added and the magnetic susceptibility increase ratio when Masago soil is used as the test soil in the method for treating powder and granular material of the present invention. It is experimental data showing the relationship between the type of alkaline agent and the magnetic susceptibility increase ratio when Masago soil is used as the test soil in the powder processing method of the present invention. It is experimental data showing the relationship between the amount of NaOH added and the magnetic susceptibility increase ratio when Masago soil is used as the test soil in the method for treating powder and granular material of the present invention. It is experimental data showing the relationship between the order of addition of chemicals and the magnetic attraction rate increase ratio when Masago soil is used as the test soil in the powder processing method of the present invention. It is experimental data showing the relationship between the amount of a chemical added and the magnetic attraction rate increase ratio when Masago soil is used as a test soil in the method for treating powder and granular material of the present invention. It is experimental data showing the relationship between the stirring means and the magnetic attraction rate increase ratio when Masago soil is used as the test soil in the powder processing method of the present invention. It is experimental data showing the relationship between the standing time after addition of a chemical and before a heating operation and the magnetic attraction rate increase ratio when Masago soil is used as a test soil in the method for treating powder and granular material of the present invention. It is experimental data showing the relationship between the heating temperature and the magnetic susceptibility increase ratio when Masago soil is used as the test soil in the powder processing method of the present invention. It is experimental data showing the relationship between heating time and magnetic susceptibility when Masago soil is used as a test soil in the powder processing method of the present invention. It is experimental data showing the relationship between the temperature increase rate and the magnetic attraction rate when Masago soil is used as the test soil in the powder processing method of the present invention. It is experimental data showing the relationship between the type of counter anion and the magnetic susceptibility increase ratio when Masago soil is used as the test soil in the powder processing method of the present invention. It is experimental data showing the relationship between the amount of Fe ²⁺ added and the magnetic susceptibility increase ratio when Masago soil is used as the test soil in the granular material processing method of the present invention. 1 shows the measurement results of the particle size distribution of black soil, which is a test soil, before and after heating in the powder processing method of the present invention. It is experimental data showing the relationship between the amount of FeCl ₂ .4H ₂ O added and the magnetic attraction increase rate when black soil is used as the test soil in the powder treatment method of the present invention. It is experimental data showing the relationship between the amount of NaOH added and the rate of increase in magnetic attraction when black soil is used as the test soil in the method for treating powder and granular material of the present invention.

FIG. 1 is a flow diagram illustrating a method for processing powder or granular material as an embodiment of the present invention. The method for treating powder or granular material according to the present invention can be roughly divided into two steps: a first step and a second step. The first stage is a step (step S1) of preparing the powder or granular material (powder or granular material) to be processed so that it can be magnetically sorted. This is a magnetic force sorting step (step S2) for sorting into magnetic objects and non-magnetic objects.

Specifically, the process of preparing powder and granules so that they can be magnetically sorted is a process in which a magnetic substance that can be attracted to a magnet is generated and adsorbed on the surface of the powder and granules (magnetic substance generation and adsorption process). The method includes a drug addition step (step S1-a) of adding a drug and a heating step (step S1-b) of heating a mixture of the drug and powder.

In this treatment method, the powder and granular material to be treated is not particularly limited, and examples of the powder and granular material include soil, incinerated ash, sludge, mixtures thereof, and materials to which pollutants adhere, adsorb, or adhere. can be mentioned. Examples of contaminants include heavy metals, dioxins, PCBs, persistent organic pollutants (POPs) such as pesticides, and radioactive substances. The radioactive substances are not limited to specific substances either, and a wide range of radioactive substances such as cesium Cs, plutonium Pu, uranium U, and radium Ra can be targeted.

Contaminated soil in which pollutants are mainly fixed, adsorbed, or adhered to the soil surface usually has a higher concentration of pollutants as the particle size becomes smaller (for example, see Table 1 in the specification of Japanese Patent No. 5313387). . This is because soil with smaller particle size has a larger specific surface area. Since this treatment method can classify contaminated soil by magnetic sorting as described later, highly concentrated contaminated soil can be separated and decontaminated.

Although the particle size of the granular material is not particularly limited, the present treatment method can be suitably used for processing granular material that is difficult to sieve. The moisture content of the powder is not particularly limited either. Even if it is bone dry or contains moisture, it can be processed as is. Even if there is a lot of water, the water will evaporate as it is heated in the heating process, but the more water there is, the more energy is required to evaporate it, so it is better for the powder to contain less water. If it is possible to dehydrate the powder, it is preferable to perform the dehydration operation in advance to lower the water content.

The powder and granular materials may include lumps. As shown in the Examples below, when a stirring operation was performed on a mixture of powder and medicine, the magnetic attraction rate decreased in the magnetic separation step, and the higher the stirring intensity, the lower the magnetic attraction rate. For this reason, it is preferable to crush such lumps in the previous stage.

Further, when crushing the lumps, it is preferable to do so in such a way that powder and granules other than the lumps are not crushed. As mentioned above, in contaminated soil in which pollutants are mainly fixed, adsorbed, or adhered to the surface of the soil, the larger the particle size, the lower the concentration of the pollutants. When such contaminated soil with large particle size is pulverized, contaminated soil with small particle size and low contamination concentration is generated, resulting in a decrease in decontamination efficiency.

In addition, some particulate materials contain organic matter such as plants, tree leaves, wood chips, root hairs, etc., and such particulate materials can also be treated with this treatment method. Since the powder processing method of this embodiment includes a heating step, the organic matter becomes carbide in this heating step.

In the present invention, divalent iron ions Fe ²⁺ and trivalent iron ions Fe ³⁺ are used to generate the magnetic material. Divalent iron ion Fe ²⁺ is supplied as a drug, but there are multiple ways of supplying trivalent iron ion Fe ³⁺ . Therefore, the chemicals to be used differ depending on the supply mode of trivalent iron ion Fe ³⁺ .

Specifically, when trivalent iron ions Fe ³⁺ are obtained from the powdered material to be treated and/or part of the divalent iron ions Fe ²⁺ supplied as a chemical undergoes a chemical change and becomes trivalent iron. When the ions are turned into Fe ³⁺ ions, an aqueous solution containing divalent iron ions Fe ²⁺ is used as the drug. When trivalent iron ions Fe ³⁺ cannot be obtained from the powder or granular material to be treated and/or when a predetermined amount of trivalent iron ions Fe ³⁺ cannot be obtained from the divalent iron ions Fe ²⁺ supplied as a drug. Sometimes, an aqueous solution containing divalent iron ions Fe ²⁺ and trivalent iron ions Fe ³⁺ is used as the drug.

Although the aqueous solution containing divalent iron ion Fe ²⁺ and the aqueous solution containing trivalent iron ion Fe ³⁺ are not particularly limited, aqueous solutions containing FeCl ₂ .4H ₂ O and FeCl ₃ are preferable. Examples of drugs containing divalent iron ion Fe ²⁺ include FeCl ₂ .4H ₂ O, FeSO ₄ .7H ₂ O, Fe(NH ₄ ) ₂ (SO ₄ ) _{2.6H 2} O, and the like. These iron salts differ in solubility in water and also in unit price. FeCl ₂ .4H ₂ O has a higher solubility than other iron salts, so it is easy to adjust the concentration, and the unit price is low, so it is preferable.

The concentration of divalent iron ions Fe ²⁺ and/or trivalent iron ions Fe ³⁺ influences the magnetic attraction force of the magnetic substance generated and adsorbed on the surface of the powder. As shown in Examples below, the magnetic attraction rate reached a peak when the divalent iron ion Fe ²⁺ in the aqueous solution had a specific concentration. On the other hand, regarding the relationship between the concentration of trivalent iron ions Fe ³⁺ and the magnetic attachment rate increase ratio, the higher the concentration of trivalent iron ions Fe ³⁺ , the lower the magnetic attachment rate.

The magnetic force of magnetic substances generated and adsorbed on the surface of powder particles is correlated with the particle size, ^cohesiveness , and amount of generation/adsorption of the magnetic substance. It is thought that these changes depending on the concentration of iron ion Fe ³⁺ . From the above, by adjusting the concentration of divalent iron ions Fe ²⁺ , the concentration of trivalent iron ions Fe ³⁺ , and the ratio of divalent iron ions Fe ²⁺ and trivalent iron ions Fe ³⁺ in the aqueous solution, A desired magnetic attraction rate can be obtained.

The amount of the drug added to the powder, ie, the amount of divalent iron ions Fe ²⁺ and/or trivalent iron ions Fe ³⁺ , also greatly influences the magnetic attraction rate. As shown in Examples below, the magnetic attraction rate increased in proportion to the amount of the drug added. This can be said to indicate that the amount of magnetic material produced and adsorbed as well as the magnetic attraction force increase in proportion to the amount of divalent iron ions Fe ²⁺ and/or trivalent iron ions Fe ³⁺ added. From the above, a desired magnetic attraction rate can be obtained by adjusting the amount of the chemical added to the powder or granule. Regarding the relationship between the amount of the chemical added and the type of soil, judging from the examples described later, it is necessary to increase the amount of the chemical added as the content of organic matter contained in the soil increases.

Further, in the drug addition step, a pH adjuster is added as a drug. The pH adjuster is an alkaline agent and is added in the form of an aqueous solution. The alkaline agent is not particularly limited, but sodium hydroxide (NaOH) is preferred in view of its ability to increase the magnetic attraction rate, unit price, ease of availability, etc., as shown in Examples below. The amount of the alkaline agent added greatly affects the magnetic attraction rate, as shown in Examples below. From the above, a desired magnetic attraction rate can be obtained by adjusting the type and amount of the alkaline agent added.

When supplying trivalent iron ion Fe ³⁺ as a drug, the following method can be considered. An aqueous solution containing divalent iron ion Fe 2+ prepared by adding a predetermined amount of divalent iron salt and an alkali agent to water, and a solution containing trivalent iron ion Fe ²⁺ prepared by adding a predetermined amount of trivalent iron salt and an alkali agent to water. An aqueous solution containing ion Fe ³⁺ is prepared separately, and these are added separately. Alternatively, these two aqueous solutions are mixed in advance and then added to the powder. Furthermore, an aqueous solution containing divalent iron ions Fe ²⁺ and trivalent iron ions Fe ³⁺ prepared by adding predetermined amounts of divalent iron salts, trivalent iron salts, and alkaline agents to water is added to the powder. .

As described in the Examples below, the method of separately adding an aqueous solution containing divalent iron ions Fe ²⁺ and an aqueous solution containing trivalent iron ions Fe ³⁺ is a method in which divalent iron ions Fe ²⁺ and trivalent iron ions Fe 2+ are added separately. The magnetic attraction rate was lower than that of the method in which iron ions (Fe ³⁺ ) were added together. Furthermore, considering the mixing after adding the drug to the powder or granules, when supplying trivalent iron ion Fe ³⁺ as a drug, divalent iron ion Fe ²⁺ and trivalent iron ion Fe ³⁺ should be mixed together. It is good to add it.

The amount of liquid of the drug added to the powder is preferably such that the liquid slightly floats on the surface of the powder. In other words, when the chemical is added to the powder or granule as the object to be treated, it is preferable that the entire powder or granule is immersed in the liquid. In this way, the powder and the drug can be brought into contact with each other reliably, and there is no need to perform any particular stirring operation. On the other hand, even if the amount of liquid added is increased more than necessary, the water will evaporate during the heating process, which is uneconomical.

When the liquid amount of the drug added to the powder or granule is reduced, a stirring and mixing operation is required to homogenize the drug and the powder or granule. This stirring and mixing operation may be performed in parallel with the addition of the drug, after the addition of the drug, or during the heating step. The device and stirring method used for stirring and mixing are not particularly limited, but it is preferable to prevent the powder from being crushed or generating dust during the stirring operation.

The heating step (step S1-b) is a step of heating the mixture of the drug and the powder. As shown in the Examples below, the magnetic attraction rate increases in proportion to the heating temperature, but conversely decreases when the temperature exceeds 300°C. Furthermore, if the heating temperature exceeds 350°C, there is a concern that dioxin will be resynthesized. From these, the heating temperature is preferably 200°C or more and 300°C or less, more preferably 250°C or more and 300°C or less, and even more preferably around 250°C. If the heating temperature is 350° C. or lower, there is no fear that magnetite will lose its magnetism (Curie point: 858 K).

The heating operation in the heating process is not particularly limited, but may include the standing time (standing time) after adding the drug to the powder or granular material until heating starts, and the rate of temperature increase from room temperature to the predetermined heating temperature. The magnetic attraction rate differs depending on the time (heating time) for which the heating temperature is maintained after reaching a predetermined heating temperature. As shown in Examples below, when the standing time was increased or the temperature increase rate was increased, the magnetic attachment rate decreased. When the heating time was 30 min or more, the magnetic attraction rate was almost constant regardless of the heating time. From the above, in the heating operation, the magnetic attraction rate can be adjusted by adjusting the standing time (standing time), temperature increase rate, and heating time after adding the drug to the powder and granular material until the start of heating.

In the heating step, it is preferable to use a stirring and mixing operation in combination from the viewpoint of uniformizing the temperature, removing moisture, and further preventing agglomeration of the powder and granules. Here, too, it is preferable to stir and mix so that the powder and granules are not crushed. The heating temperature and heating time in the heating process are basically set so that the magnetic attraction force of the magnetic material reaches the desired value, but if the powder or granules contain organic matter, this organic matter will be carbonized, and this carbide will be It is preferable to determine the heating temperature and heating time so that magnetic substances are generated and adsorbed on the surface.

The particle size and dispersibility of the magnetic substances generated and adsorbed on the surface of powder particles depend not only on the temperature and time during the heating process, but also on the atmosphere of the reaction field, specifically whether the reaction field is an oxidizing atmosphere or a reducing atmosphere. to be influenced. This affects divalent iron ions Fe ²⁺ being oxidized and changing into trivalent iron ions Fe ³⁺ . Therefore, the magnetic attraction rate can be adjusted by adjusting the atmosphere of the reaction field in the heating step.

The mechanism by which the magnetic substance is generated and adsorbed on the surface of the powder in the magnetic substance generation/adsorption process having the above configuration is considered to be as follows. Hereinafter, the granular material will be explained as soil.

When a chemical is added to soil, ion exchange occurs between monovalent ion species in the soil and divalent iron ions Fe ²⁺ and trivalent iron ions Fe ³⁺ . A chemical reaction then occurs on the soil surface, producing a magnetic substance on the soil surface, and the magnetic substance is adsorbed to the soil surface.

It is known that the cation exchange capacity (CEO) of the 2:1 type clay mineral and the 1:1 type clay mineral is about 80 times or more greater in the former. Therefore, divalent iron ions Fe ²⁺ and trivalent iron ions Fe ³⁺ are preferentially adsorbed to 2:1 type clay minerals, and magnetic substances are also preferentially generated and adsorbed on the surface of 2:1 type clay minerals. do.

As mentioned in the background art section, radioactive Cs released due to the nuclear power plant accident is deposited in the soil by rain and is eventually trapped inside the 2:1 clay. From this, it can be seen that the magnetic substance generation and adsorption step shown in this embodiment, and further the powder and granular treatment method shown in this embodiment, can be suitably used for the treatment of soil contaminated with radioactive Cs.

In this powder and granule processing method, the powder and granules obtained through the magnetic material generation adsorption step are subjected to magnetic separation in the next step, so the magnetic material generation and adsorption step yields a magnetically selected material suitable for magnetic separation. A method that can produce it efficiently is preferable. In this respect, the magnetic substance obtained by this method can have an adjustable magnetic attraction force, and the process of producing and adsorbing the magnetic substance is simple, so it can be said to be a preferable method.

From the viewpoint of magnetic separation, it is preferable that the magnetic substance generated and adsorbed on the surface of powder particles has a small particle size and is uniformly dispersed on the surface. Also, it is preferable that the amount of chemicals used to generate and adsorb magnetic substances is small.

As shown in the examples described above or below, by controlling one or more of the following group (A), it is possible to control the magnetic force of the magnetic material generated on the surface of the powder or granule, so the particle size distribution, iron content, etc. The conditions for the magnetic substance generation and adsorption step may be appropriately set according to the characteristics of the object to be treated, such as the content and the content of organic matter, as well as the target magnetic attraction rate.
(A) Divalent iron ion concentration, ratio of trivalent iron ions to divalent iron ions, type of alkali agent, concentration of alkali agent, amount of agent added, stirring intensity for the mixture of powder and granules and agent , standing time after drug addition, heating temperature, heating time, heating rate, type of anion in aqueous solution

In the magnetic sorting step (step S2), the powder particles on which magnetic substances are generated and adsorbed on the surface obtained through the previous step (step S1) are magnetically sorted. The magnetic separator and magnetic separation method used in the magnetic separation step are not particularly limited, and known magnetic separators and magnetic separation methods can be used. Note that depending on the magnetic separator and magnetic separator method, it may not be possible to process high-temperature magnetically separable materials. In such a case, a cooling step for cooling the magnetically selected material (powder or granular material) may be provided between the magnetic material generation adsorption step and the magnetic separation step.

An outline of the processing mechanism of this processing method having the above configuration is as follows. In the magnetic substance generation/adsorption step, the amount of magnetic substance generated and adsorbed onto the powder (per unit mass of the powder or granule) increases as the particle size becomes smaller due to the specific surface area. In the magnetic separation process, powder particles with small particle diameters have a small weight and generate and adsorb a large amount of magnetic substances, so they become magnetic substances. On the other hand, granular materials with large particle sizes have a large self-weight, and furthermore, the amount of magnetic material generated and adsorbed is small, so that they become non-magnetic materials.

As described above, in the magnetic substance generation/adsorption step for the powder or granule, a magnetic substance is generated and adsorbed, and the powder or granule can be classified by magnetically sorting the magnetic substance. In radioactive contaminated soil, the smaller the particle size, the higher the concentration of contaminants, so by treating radioactive contaminated soil using this treatment method, radioactive contaminated soil can be concentrated, decontaminated, etc. .

In this treatment method, the organic matter contained in the powder becomes carbide in the heating step (step S1-b), so that the volume of the object to be treated is reduced. In addition, magnetic substances are also generated and adsorbed on the surface of the carbide during the magnetic substance generation and adsorption step. Since carbide has a lower density than contaminated soil, it becomes a magnetic substance in the magnetic sorting process.

The powder and granule processing method of the present invention can be variously modified based on the powder and granule processing method of the above embodiment. Hereinafter, a modification of the method for processing powder or granular material will be described.

In the powder and granular material processing method of the above embodiment, the powder and granular material is used as it is as the object to be processed, but prior to this processing method, the powder and granular material is classified using a sieve or the like, and large particles are removed. You can. It is known that in soil contaminated with radioactive substances, the smaller the particle size, the higher the concentration of radioactive substances, and conversely, the concentration of radioactive substances in coarse particles is relatively low (for example, as described in the specification of Japanese Patent No. 5313387). (See Table 1). Therefore, if coarse particles are removed in advance and the remaining contaminated soil is magnetically sorted, radioactive contaminants can be efficiently concentrated and decontaminated.

Next, a powder processing apparatus 1 as an embodiment of the present invention will be described. FIG. 2 is a configuration diagram of the powder processing apparatus 1 of the present invention. Hereinafter, assuming that the powder is soil contaminated with radioactive substances (hereinafter referred to as contaminated soil), the configuration of a processing apparatus for powder and granules will be described.

The granular material processing device 1 of the present invention is a continuous processing device that continuously processes contaminated soil, and supplies a reaction device 31 that generates and adsorbs magnetic substances on the surface of contaminated soil, and a chemical to the reaction device 31. It includes a drug supply device 21, a contaminated soil supply device 11 that supplies contaminated soil to the reaction device 31, a cooling device 41 that cools the contaminated soil after reaction, and a magnetic separation device 51 that magnetically separates the contaminated soil after cooling.

The contaminated soil supply device 11 is a device that supplies a fixed amount of contaminated soil to the reaction device 31, and is a screw feeder 13 with a hopper 12. In addition to screw feeders, table feeders and the like are available as devices for quantitatively feeding powder and granular materials. Here, the type is not particularly important as long as it can supply a fixed amount of contaminated soil, but it is preferable that the powder or granules will not be crushed or pulverized during the conveyance process, and the surface will not be scraped off.

The drug supply device 21 is a device that supplies a fixed amount of a drug to the reaction device 31, and includes a drug supply tank 22 equipped with a stirrer 23 and a fixed amount supply pump 24. The drug supply tank 22 is filled with an aqueous solution in which a divalent iron salt and an alkaline agent are dissolved in water.

In the powder and granular material processing apparatus 1 of this embodiment, the trivalent iron ion Fe ³⁺ is not included in the chemical because the contaminated soil and the divalent iron ion Fe ²⁺ are oxidized and supplied. If trivalent iron ions Fe ³⁺ are insufficient in contaminated soil and oxidation of divalent iron ions Fe ²⁺ , trivalent iron salts may be supplied via the chemical supply device 21 .

In addition, in this embodiment, the contaminated soil and the chemical are supplied to the reaction device 31 without passing through a device that mixes the contaminated soil and the chemical because the chemical is added to the contaminated soil in an amount sufficient to soak the contaminated soil. If the amount of the chemical supplied to the soil is small, the contaminated soil and the chemical may be mixed in a mixing device and then supplied to the reaction device 31.

The reaction device 31 is a device that heats a mixture of contaminated soil and a chemical, causes the chemical to react, and generates and adsorbs a magnetic substance on the surface of the contaminated soil. The reaction apparatus 31 is an indirect heating type rotary kiln that includes an inner cylinder 32 that is connected to a drive device (not shown) and rotates, and an outer cylinder 37 that is fixed so as to cover the inner cylinder 32.

The inner cylinder 32 has an inlet portion 33 at one end for receiving contaminated soil supplied from the contaminated soil supply device 11 and a medicine supplied from the medicine supply device 21, and an inlet portion 33 at the other end for discharging the heated mixture. An outlet hood 34 is provided. A weir (not shown) is provided in a portion of the inner cylinder 32 near the inlet 33 to prevent the supplied medicine from immediately moving to the outlet hood 34 side. The supplied contaminated soil moves over the weir and toward the outlet hood 34 as the inner cylinder 32 rotates.

The inlet portion 33 and the outlet hood 34 are connected to the inner cylinder 32 to prevent leakage of gas generated within the inner cylinder 32. An exhaust port 35 is provided at the top of the outlet hood 34 for discharging gas such as water vapor generated as the mixture is heated, and an exhaust port 36 is provided at the bottom of the outlet hood 34 for discharging the heated mixture. ing.

The outer cylinder 37 is divided into three sections in the longitudinal direction, and each section is provided with a heating gas supply port 38 and a heating gas discharge port 39, and receives heating gas sent from a heating gas supply device (not shown). , the mixture in the inner cylinder 32 is heated using this as a heating medium. By supplying heating gases having different temperatures to the respective compartments, the mixture and contaminated soil in the inner cylinder 32 can be adjusted to a desired temperature and temperature distribution.

The mixture of contaminated soil and chemicals is supplied to the inner cylinder 32 in the form of a slurry, and in the process of moving from the inlet 33 of the inner cylinder 32 to the discharge port 36, it is heated for a predetermined time and at a predetermined temperature, and is coated on the surface of the contaminated soil. Generates and attracts magnetic substances. The contaminated soil with magnetic substances generated and adsorbed on its surface is discharged from the discharge port 36. On the other hand, gases such as water vapor generated during the heating operation of the mixture of contaminated soil and chemicals are guided from the exhaust port 35 to an exhaust gas treatment device (not shown).

The reaction device 31 only needs to be capable of heating a mixture of contaminated soil and a drug at a predetermined temperature for a predetermined time to generate and adsorb a magnetic substance on the surface of the contaminated soil, and the model of the device is not particularly limited. However, in terms of uniformity of reactivity and temperature, and further prevention of agglomeration of contaminated soil, it is preferable to use one having a stirring and mixing function. At this time, it is preferable that the contaminated soil is not crushed or pulverized, and the surface is not scraped off, and in this respect, a rotary kiln is a preferable device.

The cooling device 41 cools the contaminated soil discharged from the reaction device 31, on the surface of which magnetic substances are generated and adsorbed, to a temperature at which it can be supplied to the subsequent magnetic separation device 51. The cooling device 41 is a horizontal uniaxial stirring device with a jacket, and includes a horizontal uniaxial screw 43 in a stirring tank 42 , and a jacket 44 is attached to cover the stirring tank 42 . The cooling medium supplied to jacket 44 is water.

A rotary feeder 46 is provided at the outlet of the stirring tank 42 as a device for quantitatively feeding the cooled contaminated soil to the subsequent magnetic separation device 51.

The type of cooling device 41 is not particularly limited as long as it can cool the contaminated soil on which magnetic substances are generated and adsorbed on the surface discharged from the reaction device 31 to a temperature that can be supplied to the subsequent magnetic force sorting device 51. isn't it. Further, the quantitative supply device that quantitatively supplies the cooled contaminated soil to the magnetic sorting device 51 is not limited to the rotary feeder 46, but it is preferable that the device does not crush or crush the contaminated soil or scrape off the surface. .

The magnetic sorting device 51 magnetically sorts contaminated soil supplied in a fixed amount via the rotary feeder 46 . The magnetic separator 51 shown here is a known conveyor type magnetic separator, and classifies contaminated soil into magnetic materials and non-magnetic materials. Here, the magnetic separator 51 is not limited to a specific one, and various magnetic separators such as a drum-type magnetic separator and a magnetic separator capable of separating contaminated soil into three or more types can be used.

Next, a procedure for treating contaminated soil using the powder/granular material treatment apparatus 1 shown in FIG. 2 will be explained.

Contaminated soil and chemicals are sent to the inner cylinder 32 via the inlet section 33 of the reaction device 31 in a slurry state. The mixture of contaminated soil and chemicals is heated while moving through the inner cylinder 32 from the inlet portion 33 toward the outlet 36 . During this process, the chemicals react and magnetic substances are generated and adsorbed on the surface of the contaminated soil. When the contaminated soil contains plants such as root hairs, these become carbonized in the reaction device 31, and magnetic substances are generated and adsorbed on the surface similarly to the contaminated soil. The contaminated soil with magnetic substances generated and adsorbed on its surface is sent to a cooling device 41 connected to the discharge port 36 . Gas such as water vapor generated during the process of heating the mixture is led to an exhaust gas treatment device (not shown) through the exhaust port 35.

Contaminated soil on which magnetic substances have been generated and adsorbed on the surface discharged from the reaction device 31 is cooled by a cooling device 41 to a temperature at which it can be supplied to the magnetic separation device 51, and then sent to the magnetic separation device 51 via a rotary feeder 46. A fixed amount is supplied, and here it is separated into magnetic materials and non-magnetic materials.

Due to the specific surface area, the smaller the particle size of contaminated soil, the greater the amount of magnetic substances produced and adsorbed (per unit mass of contaminated soil). In addition, contaminated soil with small particle size has a small self-weight and also generates and adsorbs a large amount of magnetic substances, so it becomes a magnetic substance. On the other hand, contaminated soil with large particle size has a large self-weight and also produces and adsorbs a small amount of magnetic substances, so it becomes a non-magnetic substance.

By using the granular material processing apparatus 1 as described above, it becomes possible to sort contaminated soil by particle size, that is, to classify it. Radioactive material-contaminated soil can be decontaminated by using the present treatment apparatus 1 because the smaller the particle size of the soil, the higher the radioactive material concentration.

The granular material processing apparatus of the present invention is not limited to the processing apparatus shown in FIG. The granular material processing apparatus 1 shown in FIG. 2 is equipped with a cooling device 41 to cool the contaminated soil discharged from the reaction device 31. If the specifications are satisfied, the cooling device 41 is not necessary. In such a case, a quantitative supply device such as a rotary feeder may be installed at the outlet 36 of the reaction device 31.

When controlling the amount of magnetic substances generated and adsorbed on the surface of contaminated soil by controlling the atmosphere of the reaction field, an atmosphere gas supply pipe is installed to supply gas into the reaction device. Air, nitrogen gas, combustion exhaust gas, carbon dioxide gas, or a mixture of these gases may be supplied from here.

The granular material processing apparatus of the present invention is not limited to a continuous type processing apparatus, but may be a semi-batch type or batch type processing apparatus.

As shown in the above embodiments, by using the method and apparatus for processing powder and granular material of the present invention, contaminated soil and the like can be processed at low cost with simple operations without generating excess waste. Further, the method and apparatus for preparing a processed material of the present invention can be suitably used as a pretreatment method and a pretreatment apparatus for the method and apparatus for treating powder and granular materials of the present invention.

In addition, in the method for preparing a material to be treated and the method for treating a powder or granular material of the present invention, a liquid chemical is added to a powder or granule such as contaminated soil, and this is caused to react to generate a magnetic substance on the surface of the powder or granule. Because it is adsorbed, it is easy to generate and adsorb magnetic substances uniformly, and furthermore, the generation of dust can be suppressed. Furthermore, even if contaminated soil contains wood chips, root hairs, etc., it can be treated as is, making it a practical method and device.

In addition, the method for preparing the object to be treated and the method for treating powder or granules of the present invention can control the magnetic attraction force of the magnetic substance generated and adsorbed on the surface of the powder or granules, so that the powder can be efficiently powdered with a small amount of chemicals. It is possible to process granules. Furthermore, this processing method can be used for processing various powders and granules and for a wide range of applications.

Although preferred embodiments have been described with reference to the drawings, those skilled in the art will readily assume various changes and modifications within the obvious range upon viewing this specification. It is therefore contemplated that such changes and modifications are within the scope of the invention as defined by the claims. Further, the present invention is not limited to the embodiments described below.

Test soil (mountain sand)
Mountain sand was used as the test soil. As the mountain sand, commercially available mountain sand (masago soil) was obtained and air-dried to a moisture content of 1 wt% or less. As a result of determining the particle size of Masago soil using a test sieve and a wet laser method (in ethanol), it was found that 61.8 wt% had a particle size of over 600 μm, 7.3 wt% had a particle size of less than 75 μm, and 7.3 wt% had a particle size of less than 20 μm. was 2.1 wt%. As a result of analyzing the chemical composition of Masago soil according to JIS-M8853, it was found that it contained 2 wt% of Fe ₂ O ₃ . In addition, Masago soil contained 0.19±0.06 wt% of iron sand.

Method for preparing samples for magnetic sorting A typical procedure for preparing samples for magnetic sorting is shown below. 6 ml of the chemical was added to 10 g of Masago soil, which was the test soil, and the mixture was left at room temperature for 5 minutes. When 6 ml of the drug is added to 10 g of Masago soil, all of the Masago soil is immersed in the drug, with the drug slightly floating above the top of the Masago soil. Thereafter, the temperature was raised from room temperature to 200°C at a rate of 18°C/min in the atmosphere using a tube furnace, and then from 200°C to 250°C at a rate of 5°C/min, and held at 250°C for 2 hours. . Thereafter, it was left to cool in a desiccator, and this was used as a sample for magnetic separation. The drug is water to which predetermined amounts of NaOH, FeCl ₃ , and FeCl ₂ .4H ₂ O are added. Hereinafter, unless otherwise specified, samples for magnetic selection were prepared using the method described above.

Magnetic Sorting Method A sample was placed in a special mixing bottle 101 shown in Fig. 3, an iron core 102 was inserted into the top of the mixing bottle 101, and a neodymium magnet (surface magnetic flux density 573 mT) 103 was attached (see Fig. 3 (A)). , the mixing bottle 101 was shaken by hand for about 30 seconds (see FIG. 3(B)). Thereafter, the plastic cover 104 on the top of the bottle was removed, and the neodymium magnet 103 and iron core 102 were pulled out on the tray to collect the magnetic material (see FIG. 3(C)). Thereafter, the plastic cover 104, the neodymium magnet 103, and the iron core 102 were attached, and the residue (non-magnetic material) was magnetically separated in the same manner as before. This magnetic selection operation was performed five times for each sample.

Definition of magnetic susceptibility and magnetic susceptibility increase ratio The magnetic susceptibility is expressed by equation (1). The magnetic attraction rate increase ratio is shown by formula (2), and the magnetic attraction rate of the blank is the magnetic attraction rate of Masago soil to which no chemicals have been added and which has not been heated (hereinafter referred to as untreated soil). It is also possible to set a target magnetic attraction rate. For example, if the goal is to classify (separate) particles with a particle size of less than 20 μm contained in Masago soil, the target magnetic attraction rate will be the same as the content of particles with a particle size of less than 20 μm contained in Masago soil. . In the case of Masago soil used in this example, the target magnetic attraction rate is 2.1 wt%, and the target magnetic attraction rate ratio is 12.3.

Magnetic Attachment Rate of Untreated Soil The magnetic attachment rate of untreated Masago soil was 0.186 wt%.

Effect of Heating on Untreated Soil When only Masago soil was heated in a tube furnace at 250°C for 2 hours in the atmosphere, the magnetic attraction rate increased by 1.6 times compared to before heating. As a result of measuring the particle size of Masago soil after heating, the particle size of less than 1000 μm increased by 17.5 wt% compared to before heating. It is thought that the magnetic attraction rate increased because the number of fine particles increased due to heating and magnetic oxides were generated.

Effect of the amount of FeCl ₂ .4H ₂ O added To 10 g of Masago soil, 6 ml of a solution containing NaOH, FeCl ₂ .4H ₂ O and FeCl ₃ was added, and the mixture was heated at 250°C for 2 hours in the atmosphere using a tube furnace. Heated. Thereafter, it was left to cool and subjected to magnetic separation. The solution contains 1.0 mmol of NaOH and 0.18 mmol of FeCl ₃ . For FeCl ₂ .4H ₂ O, the concentration was varied in the range of 0.26 to 3.58 mmol.

The results are shown in Figure 4. The magnetic attraction rate increase ratio changed depending on the amount of FeCl ₂ .4H ₂ O added. In the range of 0.26 to 1.37 mmol of FeCl ₂ .4H ₂ O, the magnetic attraction rate increase ratio increased in proportion to the amount of FeCl ₂ .4H ₂ O added. On the other hand, in the range of 1.37 to 3.58 mmol of FeCl _{2.4H 2} O, the magnetic attraction rate increase ratio decreased in proportion to the amount of FeCl _{2.4H 2} O added. The magnetic attraction rate increase ratio reached a peak when the amount of FeCl ₂ .4H ₂ O added was 1.37 mmol, and the value at that time was 16.5.

Effect of Added Amount of FeCl ₃ To 10 g of Masago soil, 6 ml of a solution containing NaOH, FeCl ₂ .4H ₂ O and FeCl ₃ was added, and the mixture was heated at 250° C. in a tube furnace in the atmosphere for 2 hours. Thereafter, it was left to cool and subjected to magnetic separation. NaOH contained in the solution was 1.0 mmol, FeCl ₂ .4H ₂ O contained in three types, 0, 1.4, and 1.6 mmol, and the concentration of FeCl ₃ was varied in the range of 0 to 0.43 mmol.

The results are shown in Figure 5. The magnetic attraction rate increase ratio decreased in proportion to the amount of FeCl ₃ added when 1.4 mmol and 1.6 mmol of FeCl ₂ .4H ₂ O were added. When FeCl ₂ .4H ₂ O is 1.6 mmol, when the amount of FeCl ₃ added is 0, the magnetic susceptibility increase ratio is 15.3, and when the amount of FeCl ₃ added is 0.43, the magnetic susceptibility increase ratio is about 2. there were. When comparing the case where 1.4 mmol of FeCl ₂ .4H ₂ O was added and the case where 1.6 mmol was added, the magnetic attraction rate increase ratio was slightly higher in the former case. When FeCl ₂ .4H ₂ O was not added, the magnetic attraction rate increase ratio was approximately constant at about 2.0, regardless of the amount of FeCl ₃ added (0 to 0.43 mmol).

Influence of the type of alkaline agent To 10 g of Masago soil, 6 ml of a solution containing an alkaline agent, FeCl ₂ .4H ₂ O and FeCl ₃ was added, and the mixture was heated at 250° C. for 2 hours in the atmosphere using a tube furnace. Thereafter, it was left to cool and subjected to magnetic separation. The amount of FeCl ₂ .4H ₂ O contained in the solution is 1.61 mmol, the amount of FeCl ₃ is 0.18 mmol, and the amount of alkaline agent is 1.0 mmol. LiOH·H ₂ O, NaOH, KOH, Be(OH) ₂ , Mg(OH) ₂ , Ba(OH) ₂ , and Al(OH) ₃ were used as the alkali agent.

The results are shown in FIG. The increase ratio in magnetic attraction rate varied greatly depending on the type of alkaline agent, and the increase ratio in magnetic attraction rate was the largest when NaOH was used as the alkaline agent, with an increase ratio of 14.8.

Effect of added amount of NaOH To 10 g of Masago soil, 6 ml of a solution containing NaOH, FeCl ₂ .4H ₂ O, and FeCl ₃ was added, and the mixture was heated at 250° C. in a tube furnace in the atmosphere for 2 hours. Thereafter, it was left to cool and subjected to magnetic separation. FeCl ₂ .4H ₂ O contained in the solution was 0.18 mmol, FeCl ₃ was 0.18 mmol, and the amount of NaOH added was varied in the range of 0 to 2.0 mmol.

The results are shown in FIG. The magnetic attraction rate increase ratio differed greatly depending on the amount of NaOH added, and when NaOH was 1.0 mmol, the magnetic attraction rate increase ratio was 8.4, which was the largest.

Effect of addition order of iron ions An experiment was conducted in which the order of addition of solutions containing FeCl ₂ .4H ₂ O and FeCl ₃ (6 ml in total) was changed. In the first case, FeCl ₂ .4H ₂ O was added followed by FeCl ₃ . In the second case, FeCl ₂ .4H ₂ O was added after FeCl ₃ was added. In the third case, a mixture of FeCl ₂ .4H ₂ O and FeCl ₃ was added. The amounts added were 1.0 mmol of NaOH, 0.2 mmol and 1.3 mmol of FeCl ₂ .4H ₂ O, and 0.2 mmol of FeCl ₃ to 10 g of Masago soil. Heating and magnetic selection after addition of the drug were performed as described above.

The results are shown in FIG. The magnetic attraction rate increase ratio is highest when FeCl _{2.4H 2} O and FeCl ₃ are mixed and added at the same time, and when FeCl ₃ is added after _{FeCl 2.4H 2} O is added, the magnetic attraction rate increases. The ratio was the smallest. Furthermore, the higher the concentration of FeCl ₂ .4H ₂ O, the more pronounced the effect of the order of addition of iron ions was.

Effect of added amount of chemicals A solution containing NaOH, FeCl ₂ .4H ₂ O, and FeCl ₃ was added to 10 g of Masago soil, and heated at 250° C. in a tube furnace in the atmosphere for 2 hours. Thereafter, it was left to cool and subjected to magnetic separation. Here, the amount of solution was set to three types: 6 mL, 12 mL, and 30 mL. 6 mL of solution contains 1.0 mmol of NaOH, and 0.2 mmol of FeCl ₂ .4H ₂ O and FeCl ₃ .

The results are shown in FIG. The magnetic attraction rate increase ratio increases in proportion to the amount of the chemical added, and when 30 mL of the chemical is added to 10 g of Masago soil, that is, 5.0 mmol of NaOH, 1 mol of each of FeCl ₂ 4H ₂ O and FeCl ₃ When .0 mmol was added, the magnetic attraction rate increase ratio was 52.

Effects of stirring We investigated the relationship between the stirring procedure and the magnetic attraction rate increase ratio after adding chemicals to Masago soil. Add 6 ml of a solution containing NaOH, _FeCl2.4H2O , and _FeCl3 to ₁₀ g of Masago soil, and stir the mixed solution of Masago soil and the drug using a stirring device before heating, or leave it still for 5 min. I made him put it there. Thereafter, it was heated in the atmosphere at 250° C. for 2 hours using a tube furnace, and after cooling, it was subjected to magnetic separation. The solution contains 1.0 mmol of NaOH, 1.44 mmol of FeCl ₂ .4H ₂ O, and 0.18 mmol of FeCl ₃ .

A glass rod, an ultrasonic cleaner (AS ONE ASU-6M), a constant temperature water bath (Yamato Scientific BW101), a vortex (Thermo Fisher Scientific miniRotoS56), and a stirrer (AS ONE MN-01) were used as stirring devices.

The results are shown in FIG. The magnetic attraction rate increase ratio was the largest at 22.0 when no stirring was used, and the smallest at 2.0 when a stirrer was used. From this result, it can be seen that the higher the stirring intensity, the smaller the magnetic attraction rate increase ratio. This is thought to be due to the fact that the Masago soil was crushed during stirring and the iron concentration per unit surface area decreased.

Effect of standing time after addition of chemicals After adding chemicals to Masago soil, we investigated the relationship between the standing time (standing time) before heating and the magnetic attraction rate increase ratio. To 10 g of Masago soil, 6 ml of a solution containing NaOH, FeCl _{2.4H 2} O, and FeCl ₃ was added, allowed to stand indoors for a predetermined period of time, and then heated at 250°C for 2 hours using a tube furnace in the atmosphere. did. Thereafter, it was left to cool and subjected to magnetic separation. The solution contains 1.0 mmol of NaOH, 1.44 mmol of FeCl ₂ .4H ₂ O, and 0.18 mmol of FeCl ₃ . The standing time was 0 min, 960 min, and 1440 min.

The results are shown in FIG. The magnetic attraction rate increase ratio was highest at about 20 when the heating operation was started immediately after adding the chemical to Masago soil, and it was smaller as the standing time was longer. When the heating operation was started after leaving it for one day, the magnetic attraction rate increase ratio was 4.3.

Effect of heating temperature We investigated the relationship between heating temperature and magnetic attraction rate increase ratio. To 10 g of Masago soil, 6 ml of a solution containing NaOH, FeCl _{2.4H 2} O, and FeCl ₃ was added, and the temperature was selected within the range of 80 to 350°C using a tube furnace in the atmosphere. It was heated for 2 hours. The temperature increasing rate was 18° C./min from the heating temperature to 50° C., and the temperature increasing rate thereafter up to the heating temperature was 5° C./min. Thereafter, it was left to cool and subjected to magnetic separation. The solution contains 1.0 mmol of NaOH, 0.18 or 1.43 mmol of FeCl ₂ .4H ₂ O, and 0.18 mmol of FeCl ₃ .

The results are shown in FIG. The magnetic attraction rate increase ratio increased in proportion to the temperature within the range of 80° C. to 300° C., regardless of the amount of FeCl _{2.4H 2} O added. When the amount of FeCl ₂ .4H ₂ O added was 1.43 mmol, the magnetic attraction rate increase ratio was 14.9 at a heating temperature of 250°C and 18.9 at a heating temperature of 300°C. When the heating temperature exceeded 300° C., the magnetic attraction rate increase ratio decreased to about 7 to 8.5. When the object to be treated contains organic substances, the heating temperature is preferably 250° C. in order to suppress the generation of dioxins and carbonize the organic substances.

Effect of heating time The effect of heating time was investigated. 6 ml of a solution containing NaOH, FeCl _{2.4H 2} O and FeCl ₃ was added to 10 g of Masago soil, and the holding time (heating time) after reaching 250°C was 0 to 3 hours using a tube furnace in the atmosphere. The heating time was selected within the following range and heated for each heating time. Thereafter, it was left to cool and subjected to magnetic separation. The heating time was 0, 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0 hours. The solution contains 1.01 mmol of NaOH, 0.18 mmol of FeCl ₂ .4H ₂ O, and 0.18 mmol of FeCl ₃ .

The results are shown in FIG. The ratio of the magnetic attachment rate at each heating time to the magnetic attachment rate at a heating time of 0 hours was about 1.4 to 1.6 without much difference within the heating time range of 0.5 to 3.0 hours.

Effect of temperature increase rate The effect of temperature increase rate was investigated. To 10 g of Masago soil, 6 ml of a solution containing NaOH, FeCl _{2.4H 2} O, and FeCl ₃ was added, and the temperature was raised from room temperature to 200°C at a rate of 1.5 to 200°C using a tube furnace in the atmosphere. The heating rate was selected within the range of 36°C/min, and heating was performed at each temperature increase rate, and thereafter the temperature was increased to 250°C at a rate of 5°C/min. After heating at a heating temperature of 250° C. for 2 hours, the mixture was allowed to cool and subjected to magnetic separation. The solution contains 1.01 mmol of NaOH, 1.44 mmol of FeCl ₂ .4H ₂ O, and 0.18 mmol of FeCl ₃ .

The results are shown in FIG. The ratio of the magnetic attachment rate at each temperature increase rate to the magnetic attachment rate at a temperature increase rate of 1.5° C./min tended to decrease as the temperature increase rate increased. The magnetic attachment rate at a temperature increase rate of 36°C/min was about 0.6 compared to the magnetic attachment rate at a temperature increase rate of 1.5°C/min. If the temperature increase rate is too high, the oxidation rate of Fe ²⁺ will increase, and there is a concern that Fe ²⁺ will not be sufficient to generate the magnetic material.

Influence of counter anions We investigated the relationship between counter anions and magnetic attraction rate increase ratio. Add 6 ml of a solution containing NaOH (1.5 mmol) and FeCl _{2.4H 2} O or FeSO _{4.7H 2} O or Fe(NH ₄ ) ₂ (SO ₄ ) _{2.6H 2 O} to 10 g of Masago soil. The mixture was heated at 250° C. for 2 hours in the atmosphere using a tube furnace. Thereafter, it was left to cool and subjected to magnetic separation. The amount of Fe ²⁺ contained in each solution is 0.6 mmol.

The results are shown in FIG. The magnetic attraction rate increase ratio varied greatly depending on the type of counter anion. The magnetic attraction rate increase ratio was the highest at 18.0 when FeSO ₄ .7H ₂ O was used, and the lowest at 2.8 when FeCl ₂ .4H ₂ O was used.

Effect of the amount of Fe ²⁺ added in each iron salt The relationship between the amount of Fe ²⁺ added and the magnetic attraction rate increase ratio in each iron salt was investigated. NaOH (1.5 mmol), FeCl _{2.4H 2 O} (0.63-1.43 mmol), FeSO _{4.7H 2} O (0.63-0.90 mmol) or Fe (NH ₄ ) ₂ (SO ₄ ) _{2.6H 2} O (0.63 mmol) was added thereto, and the mixture was heated at 250° C. for 2 hours using a tube furnace in the atmosphere. Thereafter, it was left to cool and subjected to magnetic separation.

The results are shown in FIG. Since FeCl ₂ .4H ₂ O has a high solubility of 160 g/100 ml (at 10° C.), the amount added can be easily adjusted, and the amount of Fe ²⁺ added can be greatly changed. Further, when FeCl ₂ .4H ₂ O is used, the magnetic attraction rate increase ratio varies greatly depending on the amount of FeCl ₂ .4H ₂ O added, which is preferable as a drug. On the other hand, FeSO ₄ .7H ₂ O has a dissolution amount of 26 g/100 ml (at 20°C), and Fe(NH ₄ ) ₂ (SO ₄ ) 2.6H _{2 O} has a dissolution amount of 27 g/100 ml (at 20° C.). °C), and since both have low solubility, it is not possible to greatly change the amount of Fe ²⁺ added.

Classification of simulated cesium-contaminated soil Simulated cesium-contaminated soil was obtained as follows. 250 ml of a cesium chloride aqueous solution having a cesium chloride CsCl concentration of 0.14 mol/L was added to 200 g of Masago soil with a particle size of less than 2 mm, and the mixture was air-dried overnight in a fume hood. Thereafter, it was heated on a hot plate at 40 to 50°C for 2 hours to obtain simulated cesium-contaminated soil with a moisture content of 1 wt% or less.

Two types of samples for magnetic separation were prepared in the following manner. 60 ml of an aqueous solution containing FeCl ₂ .4H ₂ O and NaOH was added to 100 g of simulated cesium-contaminated soil, and heated on a hot plate at 150° C. for 2 hours to obtain a sample for magnetic separation. In one sample for magnetic separation, 60 ml of the aqueous solution contains 7.2 mmol of FeCl ₂ .4H ₂ O and 15 mmol of NaOH. In the other sample for magnetic separation, 60 ml of the aqueous solution contains 8.8 mmol of FeCl ₂ .4H ₂ O and 15 mmol of NaOH.

Appropriate amounts of two types of samples for magnetic separation were each taken, and each was subjected to magnetic separation. The magnetic selection method is as described in paragraphs [0090] and [0091] of this specification. Paragraph [0090] of this specification states that the magnetic separation operation was performed 5 times, but here the magnetic separation operation was performed 10 times. The magnetic material and the residue were each subjected to acid decomposition (60° C., 120 min), and analyzed using ICP-MS. Further, the Cs concentration was calculated using equation (3).

The results are shown in Table 1. When 7.2 mmol of FeCl _{2.4H 2} O is added to 100 g of simulated cesium-contaminated soil, the concentration ratio (magnetic Cs concentration/residue Cs concentration) is 9.6 times, and FeCl _{2.4H 2} is added to 100 g of simulated cesium-contaminated soil. When 8.8 mmol of O was added, the concentration ratio (magnetic Cs concentration/residue Cs concentration) was 5.4 times.

Test soil (black soil)
In the following experiments, black soil (organic soil) was used as the test soil. Table 2 shows the chemical composition of black soil in an unheated state. The organic matter (ignition loss; Ig-Loss) contained in the unheated black soil was 23%. Further, as a result of XRD analysis of the unheated black soil, the black soil was mainly composed of quartz, albite, anorthite, soda mica, cristobalite, pyrite, allophane, and the like.

The particle size distribution of unheated black soil (water content 13 to 14 wt%) and unheated black soil (water content 13 to 14 wt%) was heated at 250° C. for 2 hours (heated black soil). A sieve (75, 125, 250, 500, 1000 μm) was used to measure the particle size distribution. The results are shown in FIG. The unheated black soil contained 10 wt% of particles less than 75 μm, and the heated black soil contained 15 wt% of particles less than 75 μm. It is thought that the number of particles less than 75 μm increased due to the dispersion of lumps and the disappearance of organic matter by heating.

Magnetic Attachment Rate of Chemical-Free Black Soil and No-Medicine Added Heated Black Soil The magnetic attraction rate of unheated black soil to which no chemical was added was 3.4±0.1 wt%. The magnetic attraction rate of the heated black soil to which no chemicals were added was 6.0±0.1 wt%. The magnetic attraction rate increased by about 1.8 times by heating. The fact that the magnetic susceptibility increases when black soil is heated is the same as that of Masago soil, and it is thought that heating increases the number of fine particles and the generation of magnetic oxides, which increases the magnetic susceptibility. The magnetic susceptibility is expressed by formula (1), and the method for measuring the magnetic susceptibility was performed based on paragraphs [0090] and [0091] of this specification.

Here, when the goal is to classify particles smaller than 75 μm contained in heated black soil to which no chemicals have been added by magnetic sorting, the target magnetic attraction increase rate is expressed by equation (4). In this example, the content of particles less than 75 μm contained in the heated black soil to which no chemicals have been added is 15 wt%, and the magnetic attraction rate of the heated black soil to which no chemicals have been added is 6.0 ± 0.1 wt%, so the target The magnetic attraction increase rate is 2.5. Moreover, the magnetic attraction increase rate was defined by equation (5).

The method for preparing samples for magnetic separation when black soil is used as the test soil, the magnetic separation method, and the definition of magnetic susceptibility are basically the method for preparing samples for magnetic separation when using Masago soil as test soil. , the magnetic force sorting method, and the definition of magnetic attraction rate, and are as described in paragraphs [0090] to [0092] of this specification.

Effect of addition amount of FeCl ₂ .4H ₂ O A solution containing FeCl ₂ .4H ₂ O and NaOH was added to 10 g of black soil, and the mixture was heated at 250° C. for 2 hours in the atmosphere using a tube furnace. Thereafter, it was left to cool and subjected to magnetic separation. The amount of NaOH contained in the solution was 1.5 mmol, and the amount of FeCl _{2.4H 2} O added was varied within the range of 0 to 9 mmol. FeCl ₃ was not added.

The results are shown in FIG. The rate of increase in magnetic attraction changed depending on the amount of FeCl ₂ .4H ₂ O added. In the range of 0 to 4.5 mmol of FeCl 2.4H ₂ O, the rate of increase in magnetic attraction increases in proportion to the amount of FeCl _{2.4H 2} O added, and when the _amount of FeCl _{2.4H 2} O added is 0.9 mmol, it increases. The magnetic attraction increase rate was 1.03, and when the amount of FeCl ₂ .4H ₂ O added was 4.5 mmol, the magnetic attraction increase rate was 1.15. On the other hand, in the range of 4.5 to 9.0 mmol of FeCl _{2.4H 2} O, the magnetic attraction increase rate decreased in proportion to the amount of FeCl _{2.4H 2} O added. The magnetic attraction increase rate reached a peak when the amount of FeCl ₂ .4H ₂ O added was 4.5 mmol.

When comparing the relationship between the amount of FeCl ₂ .4H ₂ O added and the magnetic susceptibility among test soils, the same tendency was shown regardless of the test soil, as shown in FIGS. 4 and 18. Specifically, the magnetic attraction rate of both mountain sand (masago soil) and black soil showed a maximum value at a certain specific amount of FeCl ₂ .4H ₂ O added.

Effect of Added Amount of NaOH A solution containing FeCl ₂ .4H ₂ O and NaOH was added to 10 g of black soil, and the mixture was heated at 250° C. in a tube furnace in the atmosphere for 2 hours. Thereafter, it was left to cool and subjected to magnetic separation. The amount of FeCl ₂ .4H ₂ O contained in the solution was 4.5 mmol, and the amount of NaOH added was varied in the range of 0 to 12 mmol. FeCl ₃ was not added.

The results are shown in FIG. The magnetic attraction increase rate varied depending on the amount of NaOH added. In the range of NaOH from 0 to 9.0 mmol, the rate of increase in magnetic attraction increases in proportion to the amount of NaOH added, and the rate of increase in magnetic attraction reaches a peak when the amount of NaOH added is 9.0 mmol, and the rate of increase in magnetic attraction at that time was 2.46. On the other hand, in the range of 9.0 to 12 mmol of NaOH, the magnetic attraction increase rate decreased in proportion to the amount of NaOH added.

When comparing the relationship between the amount of NaOH added and the magnetic susceptibility in the test soils, the same tendency was shown regardless of the test soil, as shown in FIGS. 7 and 19. Specifically, the magnetic attraction rate of both mountain sand (Masago soil) and black soil showed a maximum value at a certain specific amount of NaOH added.

Effect of Heating Temperature A solution containing NaOH and FeCl ₂ .4H ₂ O was added to 10 g of black soil, and heated at 250° C. and 300° C. using a tube furnace in the atmosphere. The former is heated at 18°C/min from room temperature to 200°C, and 5°C/min from 200°C to 250°C and held at 250°C for 2 hours, and the latter is raised at 18°C/min from room temperature to 200°C. The temperature was raised at a rate of 10°C/min from 200°C to 300°C and held at 300°C for 2 hours. The solution contained 9.0 mmol of NaOH, 4.5 mmol of FeCl ₂ .4H ₂ O, and no FeCl ₃ was added.

As a result of the experiment, when heated at 250°C for 2 hours, the magnetic attachment rate was 14.7±0.7%, and when heated at 300°C for 2 hours, the magnetic attachment rate was 20.5±0.4%. The magnetic attraction increase rate was 2.4±0.1 for the former and 3.4±0.1 for the latter. Between heating temperatures of 250°C and 300°C, the latter had a higher magnetic attraction rate.

Comparing the relationship between heating temperature and magnetic susceptibility in test soils, when heating temperatures of 250°C and 300°C were used for both mountain sand (masago soil) and black soil, the latter had a higher magnetic susceptibility.

Effect of Heating Time An experiment was conducted in which a solution containing NaOH and FeCl ₂ .4H ₂ O was added to 10 g of black soil, and the heating time was varied at 250° C. using a tube furnace in the atmosphere. Specifically, one side was heated at a rate of 18°C/min from room temperature to 200°C, and at a rate of 5°C/min from 200°C to 250°C, and held at 250°C for 2 hours. On the other hand, the temperature was raised at 18°C/min from room temperature to 200°C, and at 5°C/min from 200°C to 250°C, and held at 250°C for 0.5 hour. The solution contains 0.9 mmol of FeCl ₂ .4H ₂ O, 1.5 mmol of NaOH, and no FeCl ₃ was added.

The experimental results showed that when heated at 250℃ for 2 hours, the magnetic attachment rate was 6.2±0.2%, and when heated at 250℃ for 0.5 hours, the magnetic attachment rate was 5.5±0.1%. Ta. In terms of magnetic attraction increase rate, the former was 1.0±0.0 and the latter was 0.9±0.0. When the heating time was 2 hours or 0.5 hours, the magnetization rate was slightly higher in the former case.

Comparing the relationship between heating time and magnetic susceptibility using test soil, as shown in Figure 13, in the case of mountain sand (Masago soil), the magnetic susceptibility increases with heating time in the range of 0.5 to 2 hours. It was hardly affected. On the other hand, in the case of black clay, the magnetic attraction rate increased as the heating time increased in the range of 0.5 to 2 hours.

Effect of temperature increase rate A solution containing NaOH and FeCl ₂ .4H ₂ O was added to 10 g of black soil, and an experiment was conducted in which the temperature increase rate up to 250° C. was varied using a tube furnace in the atmosphere. Specifically, one side was heated at a rate of 18°C/min from room temperature to 200°C, and at a rate of 5°C/min from 200°C to 250°C, and held at 250°C for 2 hours. On the other hand, the temperature was raised at 42°C/min from room temperature to 230°C, and at 4°C/min from 230°C to 250°C, and held at 250°C for 2 hours. The solution contains 0.9 mmol of FeCl ₂ .4H ₂ O, 1.5 mmol of NaOH, and no FeCl ₃ was added.

As a result of the experiment, the magnetic attachment rate was 6.2±0.2% in the former case where the temperature increase rate was slow, and the magnetic attachment rate was 6.7±0.2% in the latter case where the temperature increase rate was fast. In terms of magnetic attraction increase rate, the former was 1.0±0.0 and the latter was 1.1±0.0. In experiments using black soil, there was almost no effect of the temperature increase rate on the magnetic attachment rate.

Comparing the relationship between heating time and magnetic attraction rate for test soils, as shown in Figure 14, even mountain sand (Masago soil) was magnetically attracted at a heating rate of 18°C/min and a heating rate of 36°C/min. The rates are almost the same. Therefore, it can be said that within the temperature increasing rate range of 18° C./min to 42° C./min, the temperature increasing rate has almost no effect on the magnetic attraction rate, regardless of the type of soil being tested.

1 Powder processing device 11 Contaminated soil supply device 21 Chemical supply device 31 Reaction device 41 Cooling device 51 Magnetic separation device

Claims (8)

A method for preparing a material to be processed so that it can be magnetically sorted, the method comprising:
The object to be processed is a powder or granular material,
A heating step of heating the powder and granules in a state in which divalent iron ions and trivalent iron ions coexist at a temperature of 200 ° C. or more and 300 ° C. or less ,
The divalent iron ion is provided as an aqueous solution containing divalent iron ions,
A method for preparing an object to be processed, characterized in that a magnetic substance is generated and adsorbed on the surface of the powder or granular material. Claim 1, wherein the trivalent iron ions are derived from an iron component contained in the powder and/or a chemical change from divalent iron ions contained in the aqueous solution. A method for preparing a processed material as described in . 3. The method for preparing an object to be treated according to claim 1, wherein the trivalent iron ions are provided as an aqueous solution containing trivalent iron ions. In the method for preparing a workpiece according to claim 1 or 2, the aqueous solution containing divalent iron ions contains an alkaline agent,
Or, in the method for preparing a treated object according to claim 3, the aqueous solution containing divalent iron ions and/or the aqueous solution containing trivalent iron ions contains an alkaline agent. How to prepare things. The granular material contains organic matter,
5. The method for preparing an object to be treated according to claim 1 , wherein the organic substance is carbonized in the heating step, and the magnetic substance is generated and adsorbed on the surface of the carbide. When the aqueous solution containing divalent iron ions and/or the aqueous solution containing trivalent iron ions, or the aqueous solution containing an alkaline agent in these, is used as a drug, one or more of the following group (A) is controlled. 6. The method for preparing a workpiece according to claim 1 , wherein the magnetic attraction force of the magnetic substance generated and adsorbed on the surface of the powder or granular material is controlled.
(A) Divalent iron ion concentration, ratio of trivalent iron ions to divalent iron ions, type of alkali agent, concentration of alkali agent, amount of agent added, stirring intensity for the mixture of powder and granules and agent , standing time after drug addition, heating temperature, heating time, heating rate, type of anion in aqueous solution A classification step of classifying the processed material obtained by the method for preparing the processed material according to any one of claims 1 to 6 by magnetic separation ,
A method for treating a powder or granule, characterized in that the powder or granule is soil , incineration ash, sludge, organic matter, a mixture thereof, or a substance to which pollutants are fixed, adsorbed, or attached . A reaction device that heats a chemical containing an aqueous solution containing at least divalent iron ions and a powder or granule as a treatment object in the coexistence to generate and adsorb a magnetic substance on the surface of the powder or granule; A processing object preparation device comprising: a drug supply device that supplies the drug to the device;
a magnetic separator that magnetically sorts the processed material obtained through the processed material preparation device;
including;
A processing device for powder and granular material, characterized in that the powder and granular material is soil , incineration ash, sludge, organic matter, a mixture thereof, or a material to which pollutants are fixed, adsorbed, or attached .

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