JP2022030482A - compost - Google Patents

Abstract

To continuously suppress generation of hydrogen disulfide when a compost is used in a paddy field.SOLUTION: The compost according to an embodiment is a compost that includes carbide and an iron-containing substance, in which the ratio of an iron component of the iron-containing substance is 1 wt.% or more and 30 wt.% or less relative to the solid content of the compost, and 5% or more of the iron component is soluble iron which is dissolved in a Petermann citrate solution. The compost may include phosphoric acid combined to the iron component, and the ratio of a phosphoric acid component relative to the iron component may be 0.2 or more. 0.5% or more and 5% or less of the iron component may be aqueous-soluble iron which is dissolved in water.SELECTED DRAWING: Figure 1

Description

The present invention relates to compost. In particular, the present invention relates to compost containing carbides and iron components.

As the fertilizer used for paddy fields, it is desired to use compost instead of chemical fertilizer. On the other hand, when compost is used in paddy fields, there is a problem that hydrogen sulfide, which is harmful to paddy roots, is generated by the reducing action of reducing bacteria existing in the paddy fields. In addition, there is a problem that methane gas, which is one of the causes of global warming, is generated from paddy fields. This generation of hydrogen sulfide and methane gas can be suppressed by mixing iron components in the compost. As a compost containing an iron component, for example, a compost produced by mixing steelmaking slag with livestock excrement is known (Patent Document 1).

Japanese Unexamined Patent Publication No. 2012-180266

However, for example, in the compost described in Patent Document 1, the solubility of the iron component is not sufficiently explained, so that the effect in soil is not disclosed. In addition, since the iron concentration in steel slag is as low as a few percent, it is difficult to sustainably exert the effect of suppressing the generation of hydrogen sulfide and methane gas unless a large amount of compost is sprayed in the paddy field. be. One embodiment of the present invention has been made in view of the above problems, and one of the problems is to provide a compost that continuously suppresses the generation of such hydrogen sulfide.

The compost according to the embodiment of the present invention is a compost containing a carbide and an iron-containing substance, and the ratio of the iron component of the iron-containing substance to the solid content of the compost is 1% by weight or more and 30% by weight or less. More than 5% of the iron component is soluble iron that dissolves in the Petermann citrate solution.

It contains phosphoric acid bound to the iron component, and the ratio of the phosphoric acid component of the phosphoric acid to the iron component may be 0.2 or more.

Water-soluble iron may be used in which 0.5% or more and 5% or less of the iron component is soluble in water.

Water-soluble iron may be used in which 0.5% or more and 5% or less of all the irons are soluble in water.

The ratio of potassium to the solid content may be 1% by weight or more and 21% by weight or less.

The ratio of the phosphoric acid component to the solid content may be 1% by weight or more.

The ratio of water-soluble phosphoric acid dissolved in water to the solid content may be 0.01% by weight or more.

The ratio of soluble phosphoric acid dissolved in the Petermann citrate solution to the solid content may be 1% by weight or more.

The ratio of ash to the solid content may be 5% by weight or more and 30% by weight or less, and the ratio of organic carbon to the solid content may be 10% by weight or more and 40% by weight or less.

The ratio of manganese to the solid content may be 0.005% by weight or more and 0.2% by weight or less.

The ratio of boric acid to the solid content may be 1 ppm or more and 50 ppm or less.

The ratio of zinc to the solid content may be 1 ppm or more and 700 ppm or less.

The percentage of water may be 30% by weight or more and 80% by weight or less.

According to the compost according to the embodiment of the present invention, the generation of hydrogen sulfide can be continuously suppressed when the compost is used in a paddy field. In addition, by using the compost in paddy fields, it is possible to increase the redox potential around the roots of plants and suppress the action of anaerobic methanogens, which causes the generation of methane gas from paddy fields. It can be suppressed. In addition, by using the compost in paddy fields, it is possible to form a film of iron oxide around the roots of plants, and it is possible to protect the roots from harmful components such as hydrogen sulfide and methane gas.

It is a flowchart which shows the manufacturing method of compost which concerns on one Embodiment of this invention.

Hereinafter, the compost and the method for producing the compost according to the embodiment of the present invention will be described with reference to the drawings. However, the compost and the method for producing compost in one embodiment of the present invention can be carried out in many different embodiments, and are not construed as being limited to the contents of the examples shown below.

In the following embodiments, unless otherwise stated, "soluble" refers to a fertilizer component that is insoluble in water but soluble in a Petermann citrate solution. In this embodiment, "soluble iron" refers to iron that is insoluble in water but soluble in a Petermann citrate solution. Similarly, "soluble phosphoric acid" refers to phosphoric acid that is insoluble in water but soluble in Petermann citrate solution. The Petermann citrate solution is dissolved by adding water to 173 g of citric acid monohydrate specified in JIS K 8283, gradually adding ammonia water corresponding to 42 g of nitrogen while cooling, and then adding water after cooling. Refers to 1000 ml. Soluble iron and soluble phosphoric acid are iron and phosphoric acid that are not immediately soluble in weak acids such as root acid from the roots of crops, but are slightly more soluble in acids than root acid. Therefore, soluble iron and soluble phosphoric acid gradually dissolve from the compost, and a long-term fertilizing effect can be obtained.

"Water-soluble" refers to a fertilizer component that dissolves in water. In the present embodiment, "water-soluble iron" refers to iron that dissolves in water. Similarly, "water-soluble phosphoric acid" refers to phosphoric acid that dissolves in water. Water-soluble iron and water-soluble phosphoric acid are iron and phosphoric acid that are rapidly dissolved in the water contained in the soil and absorbed by the crop. Therefore, water-soluble iron and water-soluble phosphoric acid can obtain a fast-acting fertilizing effect.

In the following embodiments, a substance containing iron (for example, zero-valent iron) and an iron compound (for example, iron oxide or iron phosphate) contained in compost is referred to as an "iron-containing substance". The component of the iron element contained in the iron-containing substance is called "iron component". The iron component contained in the iron-containing substance corresponds to all the iron ions contained in the solution obtained by dissolving the iron and the iron compound contained in the compost in aqua regia, for example. When the ratio of soluble iron to the iron component contained in the compost is shown, the iron component contained in the compost (in addition to the iron component existing separately from the carbide in the compost, the iron component supported by the carbide is used. The ratio of soluble iron to (including) is shown.

The above soluble iron, water-soluble iron, and iron components are determined by ICP emission spectroscopy for the solutions obtained for each as described above. Further, the above-mentioned soluble phosphoric acid, water-soluble phosphoric acid, and all phosphoric acid contained in compost (hereinafter, referred to as "phosphoric acid component") are determined by the ammonium vanadomolybdate absorptiometry.

[ICP emission spectroscopy and ammonium vanadomolybdate absorptiometry]
The ICP emission spectroscopic analysis method and the ammonium vanadomolybdate absorptiometry are test methods based on the fertilizer test method (2018) (written by the Food and Agricultural Science and Fisheries Consumption Safety Technology Center), respectively. The fertilizer test method is a test method (evaluation method) specified by the Ministry of Agriculture, Forestry and Fisheries, and is a test method in which reagents and equipment used for the test are specified by JIS standards and the like. The iron component, soluble iron, and water-soluble iron described in the following embodiments are obtained by the method described in the ICP emission spectroscopic analysis method of the above-mentioned fertilizer test method (2018). The phosphoric acid component, soluble phosphoric acid, and water-soluble phosphoric acid were obtained by the method described in the above-mentioned fertilizer test method (2018), ammonium vanadomolybdate absorptiometry.

"Solid content" refers to a solid portion (nonvolatile substance) obtained by removing water from an object.

[1. Compost composition]
First, the composition of compost will be described. The compost according to the present embodiment includes compost material, carbides and iron-containing substances. In this embodiment, the iron-containing substance may be present separately from the compost material and the carbide in the compost. Alternatively, the iron-containing material may be supported on carbides. When the iron-containing substance is supported by the carbide, specifically, the iron-containing substance is present on the surface of the carbide (the outer surface of the carbide and the surface of the region surrounded by the carbide) or inside the pores. Means.

As the compost material, a general (for example, commercially available) compost material can be used. For example, as the compost material, a vegetable compost material and an animal compost material can be used. As the plant compost material, park compost material, rice husk compost material, leaf mold and the like can be used. As the animal compost material, cow manure compost material, horse manure compost material, pig manure compost material, fermented chicken manure and the like can be used.

As the carbide, a carbide obtained by carbonizing biomass can be used, and typically, a carbide obtained by carbonizing lignocellulosic can be used. As lignocellulosic, wood, particle board, litter, agricultural waste, sewage, silage, grass, rice husks, bagasse, cotton, jute, hemp, flax, bamboo, sisal hemp, abaca, straw, straw, corn stalk, corn stow One or more materials selected from the group consisting of bagasse, switchgrass, alfalfa, hay, palm hair, seaweed, algae, and mixtures thereof can be used.

The iron-containing substance contained in the compost is at least one of zero-valent iron, divalent iron, trivalent iron, iron oxide, iron chloride, iron nitrate, iron sulfate, iron acetate, iron oxalate, and the like. including. The iron oxide may be, for example, FeO (ustite), Fe ₂ O ₃ (hematite or maghemite), Fe ₃ O ₄ (magnetite), or the like. The above iron may be one kind of compound or may be a plurality of compounds.

Further, the iron-containing substance contained in the compost contains iron phosphate in which the iron component and the phosphorus contained in the phosphate ion are bonded. When a carbide containing an iron component is put into water, iron is ionized to form a hydroxide such as iron oxyhydroxide (FeOOH). When water contains phosphoric acid, the hydroxide can react with phosphoric acid ions existing in the water to form iron phosphate and adsorb and fix it to carbides.

In the present embodiment, a part of the phosphoric acid is bound to an iron component contained in an iron-containing substance and is typically adsorbed. That is, the phosphorus bound to the iron component is present on the surface of the carbide or inside the pores. In the phosphorus bound to the iron component, the ratio of the phosphoric acid component of the phosphoric acid bound to the iron component to the iron component is 0.2 or more, 0.25 or more, 0.3 or more, or 0.4 or more. be.

Here, iron-containing substances containing at least one of zero-valent iron, divalent iron, trivalent iron, iron oxide, iron chloride, iron nitrate, iron sulfate, iron acetate, iron oxalate, etc. The carried charcoal is referred to as "iron-containing charcoal", and the carried charcoal carrying an iron-containing material containing iron phosphate is referred to as "iron-phosphorus-containing charcoal".

The ratio of the iron component of the iron-containing substance to the solid content of compost is 1% by weight or more and 30% by weight or less, 2% by weight or more and 20% by weight or less, 3% by weight or more and 15% by weight or less, or 5% by weight or more and 10% by weight or less. Is. The ratio of nitrogen to the solid content of the compost is 1% by weight or more and 21% by weight or less, 2% by weight or more and 18% by weight or less, 3% by weight or more and 15% by weight or less, or 5% by weight or more and 10% by weight or less. .. The ratio of potassium to the solid content of the compost is 1% by weight or more and 21% by weight or less, 2% by weight or more and 18% by weight or less, 3% by weight or more and 15% by weight or less, or 5% by weight or more and 10% by weight or less. ..

The proportion of soluble iron in the iron components is 5% or more, 7% or more, 10% or more, or 15% or more. The proportion of water-soluble iron in the iron components is 0.5% or more and 5% or less, and 1% or more and 3% or less. Since soluble iron is difficult to dissolve in water, the proportion of soluble iron is higher than that of water-soluble iron, so that the proportion of iron components washed away by rainwater can be reduced.

The ratio of the phosphoric acid component to the solid content of the compost is 1% by weight or more, 2% by weight or more, 3% by weight or more, or 5% by weight or more. The ratio of water-soluble phosphoric acid to the solid content of the compost is 0.01% by weight or more, 0.02% by weight or more, 0.03% by weight or more, or 0.05% by weight or more. The ratio of soluble phosphoric acid to the solid content of the compost is 1% by weight or more, 2% by weight or more, 3% by weight or more, or 5% by weight or more.

Phosphoric acid that binds to the iron component carried on the carbide contains inorganic phosphorus and organic phosphorus, which are classified into soluble and insoluble, respectively. Examples of the soluble inorganic phosphorus include orthophosphoric acid, metaphosphoric acid, pyrophosphoric acid, polyphosphoric acid and the like. Examples of the soluble organic phosphorus include phosphoric acid esters such as phospholipids and pesticides. Examples of insoluble inorganic phosphorus include phosphates of metals such as calcium, iron, aluminum, sodium and potassium. Examples of insoluble organic phosphorus include ecology such as bacteria and plankton, or constituents of carcasses. The phosphoric acid may be present separately from the carbide in the compost material.

The ratio of the ash content to the solid content of the compost is 5% by weight or more and 30% by weight or less, 6% by weight or more and 28% by weight or less, 7% by weight or more and 25% by weight or less, or 10% by weight or more and 20% by weight or less. The ratio of organic carbon to the solid content of the compost is 10% by weight or more and 40% by weight or less, 12% by weight or more and 35% by weight or less, or 15% by weight or more and 30% by weight or less. The ratio of manganese to the solid content of the compost is 0.005% by weight or more and 0.2% by weight or less, 0.01% by weight or more and 0.18% by weight or less, 0.015% by weight or more and 0.15% by weight or less, or It is 0.02% by weight or more and 0.1% by weight or less. The percentage of water in the compost is 30% by weight or more and 80% by weight or less, 35% by weight or more and 75% by weight or less, 40% by weight or more and 70% by weight or less, 45% by weight or more and 65% by weight or less, or 50% by weight or more and 60% by weight. % Or less.

The above ash content refers to the ash produced by the firing step (S140) of the granulated product described later. Specifically, the ash content is a metal such as calcium or potassium, silicic acid or the like, which is contained in the raw material of the carbide and remains in the firing step.

Further, the organic carbon refers to a binder described later in which an organic binder is fired by the firing step (S140). Specifically, organic carbon includes sugar honey, waste sugar honey, starch, dextrin, corn starch, rice bran, polyvinyl alcohol, pulp waste liquid, lignin sulfonate, carboxymethyl cellulose, hydroxypropylmethyl cellulose, sodium alginate, and phenol, which are used as organic binders. It is a fired resin, tar pitch, or the like.

The organic carbon content can be calculated by subtracting the inorganic carbon content from the total carbon content. The total carbon content can be calculated, for example, based on the amount of carbon dioxide generated by burning the sample. Further, the content of inorganic carbon can be calculated based on, for example, the amount of carbon dioxide liberated from carbonate or the like by acidifying and heating the sample. The combustion temperature when measuring the total carbon content is preferably higher than the firing temperature in the firing step (S140). For example, if the firing temperature in the firing step (S140) is 850 ° C., the combustion temperature when measuring the total carbon content can be 900 ° C. Further, the heating temperature when measuring the content of inorganic carbon is preferably lower than the firing temperature in the firing step (S140). The heating temperature when measuring the content of inorganic carbon is, for example, 200 ° C. By using a total organic carbon meter, the total carbon content and the inorganic carbon content can be measured and the organic carbon content can be calculated.

The ratio of boric acid to the solid content of the compost is 1 ppm or more and 50 ppm or less, 2 ppm or more and 45 ppm or less, 3 ppm or more and 40 ppm or less, 5 ppm or more and 30 ppm or less, or 10 ppm or more and 20 ppm or less. The ratio of zinc to the solid content of the compost is 1 ppm or more and 700 ppm or less, 2 ppm or more and 600 ppm or less, 3 ppm or more and 500 ppm or less, 5 ppm or more and 400 ppm or less, or 10 ppm or more and 300 ppm or less.

The carbides contained in the compost have a pellet shape. Here, the pellet shape means a shape having a certain height. The pellet shape of the carbide is, for example, a substantially cylindrical column, a substantially elliptical column, a substantially polygonal column, or the like. The pellet shape of the carbide is generally determined by the shape of the granulated product described later, and the height of the pellet shape is 1 mm or more and 20 mm or less, 3 mm or more and 15 mm or less, or 6 mm or more and 12 mm or less. The diameter of the pellet shape (maximum width in the direction perpendicular to the height) is 1 mm or more and 20 mm or less, 2 mm or more and 10 mm or less, or 3 mm or more and 6 mm or less. In the method for producing compost according to the present embodiment, it is possible to control the size of carbides. Therefore, the size of the carbide is preferably in the above range, which is easy to use and has a high adsorption effect.

As described above, according to the compost according to the present embodiment, for example, the ratio of the iron component of the iron-containing substance to the solid content of the compost is 1% by weight or more and 30% by weight or less, and the ratio of soluble iron among the iron components. When 5% or more, the compost contains 0.05% by weight or more and 1% by weight or less of soluble iron with respect to the solid content of the compost. As mentioned above, soluble iron does not dissolve immediately in a weak acid such as root acid from the roots of crops, but it dissolves in an acid slightly stronger than root acid, so it gradually dissolves from the compost and generates hydrogen sulfide for a long period of time. Can be obtained. Moreover, when the amount of soluble iron in the soil increases, the amount of silicic acid absorbed in the soil can be increased. When the concentration of silicic acid in the soil increases, the paddy rice is less likely to fall, the light receiving posture is improved, and photosynthesis becomes active. As a result, the growth of rice does not depend on nitrogen, the nitrogen content of brown rice decreases, the umami taste increases, and blast disease can be prevented.

In addition to the effect of suppressing the generation of hydrogen sulfide, the iron component forms an iron oxide film around the roots of crops. The iron oxide film can protect the roots from hydrogen sulfide, methane gas, and the like. In addition, the redox potential around the compost can be increased, and the action of anaerobic methanogens can be suppressed, and as a result, the generation of methane gas can be suppressed.

[2. Compost manufacturing method]

A method for producing compost according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a flowchart showing a method for producing compost according to an embodiment of the present invention.

As shown in FIG. 1, the compost production method includes a mixing step (S110), a kneading step (S120), a granulation step (S130), a baking step (S140), a phosphorus addition step (S150), and a compost mixing step (S160). )including. Hereinafter, each step will be described. An iron-containing carbide is formed by the mixing step (S110) to the firing step (S140), and phosphorus is added to the iron-containing carbide by the phosphorus addition step (S150) to form an iron-phosphorus-containing carbide, and the compost mixing step (S160). The iron-phosphorus-containing carbides are mixed with the compost material to form compost.

[2-1. Mixing step (S110)]
In the mixing step (S110), the carbide and the iron compound are mixed.

The charcoal used in the mixing process is raw wood (including thinned wood such as hardwood, conifer, bamboo, and forest waste), waste wood from sawmills or wood processing factories (including sawdust, bark, chips, and scraps). It can be produced by carbonizing organic substances such as vegetable shells, building demolition materials, or wood-based waste materials for furniture materials.

Carbonization of organic matter is carried out by heating the organic matter under an inert gas atmosphere such as nitrogen gas or argon gas, an oxygen-free atmosphere, a low oxygen atmosphere, a reducing atmosphere, or a reduced pressure atmosphere. When carbonizing organic substances in a reduced pressure atmosphere, a low vacuum state of 100 Pa or more and 10 ⁵ Pa or less, a medium vacuum state of 0.1 Pa or more and 100 Pa or less, a high vacuum state of ^10-5 Pa or more and 0.1 Pa or less, or ^10-5 . It can be performed in an ultra-high vacuum state of Pa or less. When carbonizing an organic substance in a low oxygen atmosphere, the oxygen concentration can be 0.01% or more and 3% or less, or 0.1% or more and 1% or less. The heating temperature for carbonizing organic matter is 400 ° C. or higher and 1200 ° C. or lower, 500 ° C. or higher and 1100 ° C. or lower, 600 ° C. or higher and 1000 ° C. or lower, or 700 ° C. or higher and 900 ° C. or lower. The heating time is 10 minutes or more and 10 days or less, or 10 minutes or more and 5 hours or less.

Carbonization of organic matter is internal or external heating, batch open or closed charcoal furnaces, continuous rotary kilns or rocking carbonizations, screw furnaces, heating chambers, or covered heat-resistant vessels ( It can be done using a fire pot). The internal heat type is a carbonization furnace that secures the heat required for carbonization from the material, and can carbonize organic substances by supplying oxygen necessary for burning the material. The external heat type is a carbonization furnace that supplies heat required for carbonization from the outside, and can carbonize organic substances by blocking oxygen.

When the organic matter is heated under reducing conditions, the composition of the organic matter begins to decompose during the temperature rise (for example, about 280 ° C.), and the oxygen or hydrogen in the organic matter becomes a gas such as carbon dioxide, carbon monoxide, hydrogen, or hydrocarbon. The organic matter changes to amorphous carbon with a large amount of carbon component. Continued heating at higher temperatures further reduces oxygen or hydrogen in the organic matter, producing carbides composed of high-purity fixed carbon and ash. Since the water or constituents in the organic matter are desorbed as a volatile gas or the like, the carbides produced by the carbonization of the organic matter become porous in which a large number of continuous porosities of various sizes are formed. In addition, the carbonized material produced by the progress of carbonization as the carbonization temperature rises has heat resistance (fire resistance), adsorptivity, or conductive properties.

When mixing the carbide and the iron compound, the particle sizes of the carbide and the iron compound may be adjusted. By adjusting the particle size of each of the carbide and the iron compound, the carbide and the iron compound can be uniformly mixed. The adjustment of the particle size of each of the carbide and the iron compound is performed by crushing the carbide or the iron compound. In particular, since the particle size of the carbide is often larger than the particle size of the iron compound, the carbide may be crushed and the particle size of the carbide may be adjusted to the particle size of the iron compound.

Carbides and iron compounds can also be crushed in the kneading step (S120) described later, but it is difficult to finely adjust the particle size in the kneading step (S120). Therefore, when adjusting the particle sizes of the carbide and the iron compound, it is preferable to adjust the particle sizes of the carbide and the iron compound in advance in the mixing step (S110).

The sizes of carbides and iron compounds are not particularly limited, but for example, both carbides and iron oxide have a particle size of 10 μm or more and 20 mm or less, carbides have a particle size of 10 μm or more and 20 mm or less, and iron oxide has a particle size of 10 μm to 10 mm or less, or carbides. 200 has a particle size of 50 μm to 2 mm or less and iron oxide has a particle size of 100 μm to 1 mm or less. When the sizes of the carbide and the iron compound are in the above range, not only the carbide and the iron compound are uniformly mixed, but also the carbide and the iron compound are uniformly dispersed in the organic binder in the kneading step described later. Can be made to.

In mixing the carbide and the iron compound, a certain amount of water may be added. By adding water, it is possible to prevent the generation of dust in the mixing step (S110), and it is possible to uniformly knead the carbide and the iron compound in the kneading step (S120) described later.

By the above mixing step (S110), a mixture of carbide and iron compound is produced.

[2-2. Kneading step (S120)]
In the kneading step (S120), an organic binder is added to the mixture (carbide and iron compound) and kneaded to produce a paste.

Examples of the organic binder include sugar honey, waste sugar honey, starch, dextrin, corn starch, rice bran, polyvinyl alcohol, pulp waste liquid, lignin sulfonate, carboxymethyl cellulose, hydroxypropyl methyl cellulose, sodium alginate, phenol resin, tar pitch and the like. Can be used. The organic binder may contain one kind of material or may contain a plurality of kinds of materials. In particular, as the organic binder, molasses or molasses is preferable. Molasses has a lot of solid components, so it is easy to harden the paste. Further, since molasses contains a large amount of carbon components, the granulated product can be efficiently reduced in the baking step (S140) described later. Further, molasses is inexpensive and has few harmful components, so that the production cost of iron-containing carbide can be suppressed, and the produced iron-containing carbide can be used as a safe fertilizer.

The viscosity of the organic binder can be adjusted as needed. For example, water or an organic solvent can be added to the organic binder to adjust the viscosity of the organic binder. If the viscosity of the organic binder is too high, it will be difficult to knead. Further, if the viscosity of the organic binder is too small, the viscosity of the paste must be adjusted before the granulation step (S130) described later. The viscosity of the paste is adjusted by evaporating the added water or organic solvent, which not only requires the step of evaporating the water or organic solvent, but also of the carbides and iron compounds by evaporating the water or organic solvent. Aggregation occurs and the dispersibility of carbides and iron compounds in the organic binder is reduced. Therefore, it is preferable that the viscosity of the organic binder is adjusted before kneading with the mixture.

The amount of the organic binder added is also based on the amount of the solid component of the carbide. The ratio of the amount of solid component (α) of the carbide to the amount of organic binder (γ) is α: γ = 100: 10 to 1000, α: γ = 100: 100 to 500, or α: γ = 100: 100. ~ 300.

In the kneading step (S120), the parameter that determines the dispersibility of the carbide and the iron compound in the organic binder is not only the mixing ratio of the mixture and the organic binder. The dispersibility in the mixing step (S110) can also be controlled by parameters such as the temperature of the kneader and the time. Therefore, the kneading machine will be described below.

A kneader can be used for kneading the mixture and the organic binder. As the kneader, for example, a single-screw kneader, a twin-screw kneader, a mixing roll, a kneader, a Banbury mixer, or the like can be used.

As the above-mentioned kneader, a kneader having a mixing function may be used. In that case, the mixing step (S110) and the kneading step (S120) can be continuously performed. For example, carbides and iron compounds are put into a kneader and mixed. Subsequently, the organic binder is put into the kneader and kneaded with the mixture. Carbides, iron compounds, and organic binders can be put into the kneader all at once and mixed and kneaded, but the carbides and iron compounds are likely to aggregate and bubbles are likely to be generated. Therefore, the mixing step (S110) and the kneading step (S120) may be performed separately. Further, in the kneading step (S120), by using a kneading machine, a certain amount of the organic binder can be added to the mixture at a constant speed.

The kneading temperature can be arbitrarily set, but is 0 ° C. or higher and 50 ° C. or lower, or 10 ° C. or higher and 40 ° C. or lower. The kneading time is 1 second or more and 1 hour or less, 1 minute or more and 30 minutes or less, or 1 minute or more and 15 minutes or less. By setting the parameter of the kneading step (S120) in the above range, the dispersibility of the carbide and the iron compound in the organic binder can be optimized.

By the above kneading step (S120), a paste in which carbides and iron compounds are dispersed is produced in an organic binder.

[2-3. Granulation process (S130)]
In the granulation step (S130), the paste is granulated to produce a granule containing a carbide, an iron compound, and an organic binder.

The production of the granulated product can be performed using a granulator. As the granulator, for example, a compression type granulator, an extrusion type granulator, a roll type granulator, a blade type granulator, a melt type granulator, a spray type granulator, or the like can be used. .. An extrusion type granulator can be used in the production of columnar granules. Here, the production of granulated products using an extrusion type granulator will be described.

In the extrusion type granulator, the paste formed into a predetermined shape is extruded from the mounted die. The extruded paste is cut to a predetermined length to produce pellet-shaped granules in which the extrusion direction is the height direction. By adjusting the cutting speed of the extrusion type granulator (rotational speed in the case of the rotary cutting method), the length of the granulated product (height of the pellet shape) can be adjusted. Further, by adjusting the opening diameter of the die, the diameter of the granulated product (diameter when the cross-sectional shape is circular) can be adjusted. Therefore, by using an extrusion type granulator, it is possible to produce a granulated product having a pellet shape (for example, a columnar shape) whose size is controlled.

The length of the granulated product is 1 mm or more and 20 mm or less, 3 mm or more and 15 mm or less, or 3 mm or more and 12 mm or less. The diameter of the granulated product is 1 mm or more and 20 mm or less, 2 mm or more and 10 mm or less, or 3 mm or more and 6 mm or less. When the size of the granulated product is within the above range, the iron compound can be sufficiently reduced in the firing step (S140) described later, so that the phosphorus adsorption effect of the iron-containing carbide can be enhanced.

The cross-sectional shape of the granulated product is not limited to a circular shape. By changing the opening shape of the die, the cross-sectional shape of the granulated product can also be changed. The cross-sectional shape of the granulated product may be, for example, an ellipse or a polygon. That is, the granulated product may have a pellet shape of an elliptical column or a polygonal column as well as a cylinder.

In the granulation step (S130), an auxiliary agent may be added so that the pellet shape of the granulated product is stable. As the auxiliary agent, for example, an organic resin such as polyester resin, acrylic resin, phenol resin, epoxy resin, silicone resin, polyimide resin, polystyrene resin, or urethane resin can be used. In the firing step (S140) described later, these organic resins are carbonized, and the carbides can also function as iron-containing carbides.

By the above granulation step (S130), a granulated product containing a carbide, an iron compound, and an organic binder is produced.

[2-4. Baking step (S140)]
In the firing step (S140), the granulated product is fired to produce iron-containing carbides.

Firing of the granulated product is performed by heating the granulated product in a reducing atmosphere. The granulated product contains an organic binder. Heating an organic binder produces reducing gases such as carbon monoxide gas, hydrogen gas, hydrogen sulfide gas, sulfur dioxide gas, or hydrocarbon gas. Therefore, a reducing atmosphere can be formed by using the reducing gas generated from the granulated product without separately introducing the reducing gas. That is, the iron compound can be reduced by using the reducing gas generated from the granulated product. Further, since the reducing gas can be generated inside the granulated product, the iron compound inside the granulated product can be sufficiently reduced. Further, the iron compound is reduced to iron by the reducing gas from the organic binder around the iron compound, so that the iron compound has a structure in which iron is contained in the porosity of the iron-containing carbide after firing. Therefore, the amount of phosphorus adsorbed on the iron-containing carbide can be increased.

Many reducing gases are difficult to handle from the viewpoint of explosiveness and flammability. Therefore, since the generated reducing gas is diluted and exhausted, the inert gas may be contained in the firing of the granulated product. As the inert gas, for example, nitrogen gas or argon gas can be used. When an inert gas is used, for example, nitrogen gas may be flowed so that the concentration of carbon monoxide in the firing furnace is 1% or more and 20% or less.

Further, not only the reducing gas generated from the organic binder but also the reducing gas such as carbon monoxide gas, hydrogen gas, hydrogen sulfide gas, sulfur dioxide gas, hydrocarbon gas, or a mixed gas thereof is used. It is also possible to form a reducing atmosphere. However, even in this case, the amount of the reducing gas can be reduced as compared with the conventional method for producing an iron-containing carbide.

The heating temperature in firing the granulated product is 400 ° C. or higher and 1200 ° C. or lower, 400 ° C. or higher and 900 ° C. or lower, or 700 ° C. or higher and 900 ° C. or lower. The heating time is 1 minute or more and 10 hours or less, or 10 minutes or more and 5 hours or less. In the method for producing an iron-containing carbide according to the present embodiment, the iron compound can be reduced by using a reducing gas generated from an organic binder, so that the heating temperature is higher than that in a normal method for producing an iron-containing carbide. It is possible to reduce the heating time or shorten the heating time.

By calcining the granulated product, the organic binder is changed to carbide and the iron compound is changed to iron. Iron-containing carbides are produced by the above firing steps.

[2-5. Phosphorus addition step (S150)]
In the phosphorus addition step (S150), the target substance is added to the above iron-containing carbide. In this embodiment, phosphorus is added to the iron contained in the above iron-containing carbide. For example, by immersing an iron-containing carbide in an aqueous solution containing phosphorus, iron ions and phosphate ions react with each other to form the iron-phosphorus-containing carbide in which phosphorus is added to the iron. The degassing treatment (decompression treatment) may be performed while the iron-containing carbide is immersed in the above aqueous solution. Further, the container containing the aqueous solution may be vibrated during the degassing treatment. If the compost material used in the following compost mixing treatment (S160) contains sufficient phosphorus to be added to the iron-containing carbides, the phosphorus addition step (S150) may be omitted. Instead of adding phosphoric acid to the iron-containing carbide in the aqueous solution, phosphorus may be added by mixing the iron-containing carbide and solid (for example, powdery) phosphorus.

[2-6. Compost mixing step (S160)]
In the compost mixing step (S160), the above-mentioned iron-phosphorus-containing carbide or iron-containing carbide (iron-containing carbide before phosphorus is adsorbed) is mixed with the compost material. By this step, the compost according to this embodiment is formed.

Although one embodiment of the present invention has been described above with reference to the drawings, the present invention is not limited to the above-described embodiment and can be appropriately modified without departing from the spirit of the present invention. The above steps S110 to S140 are one aspect of the iron-containing carbide production step, and are not limited to the above steps. For example, a product to which a person skilled in the art appropriately adds, deletes, or changes the design based on the compost of the present embodiment is also included in the scope of the present invention as long as the gist of the present invention is provided. Further, each of the above-described embodiments can be appropriately combined as long as there is no contradiction with each other, and technical matters common to each embodiment are included in each embodiment even if there is no explicit description.

Of course, other effects different from the effects brought about by the embodiments described above, which are obvious from the description of the present specification or which can be easily predicted by those skilled in the art, will naturally occur. It is understood that it is brought about by the present invention.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples.

<Example 1>
As a carbide, 300 g of irregularly shaped charcoal and 83.3 g of iron oxide were mixed for 3 minutes to obtain a mixture. The water content of charcoal was 7.5%, and the solid component of charcoal was 300 × 92.5% = 277.5 g. Therefore, the ratio of the amount of solid components of charcoal to the amount of iron oxide was 277.5: 83.3, which was approximately 10: 3.

Next, the mixture was put into a kneader (manufactured by Dalton Corporation, model: KDRJ-10), 465 g of molasses was added over 2 minutes at room temperature, and the mixture was kneaded for 3 minutes to obtain a paste. The ratio of the amount of solid components of charcoal to the amount of molasses was 277.5: 465, which was approximately 10:17.

Next, the paste was put into a granulator (manufactured by Dalton Corporation, model: F-5) to obtain pellet-shaped granules having a diameter of 8 mm and a height of 40 mm under the condition of a rotation speed of 112 rpm. ..

Next, the granulated product was calcined at 750 ° C. for 3 hours in a nitrogen atmosphere to obtain iron-containing carbide A.

A sewage sludge dewatering separation solution was passed through a column packed with 2 kg of iron-containing carbide A at a flow rate of 2 L / day for 4 days. The sewage sludge dehydration separation liquid used here is a filtrate obtained by centrifuging the sludge at a sewage treatment plant in Okinawa Prefecture. As a result, the iron-containing carbide adsorbed phosphorus in the filtrate, and iron-phosphorus-containing carbide A was formed.

After that, the iron-phosphorus-containing carbide A on which phosphorus was adsorbed was naturally dried. Then, the iron-phosphorus-containing carbide A was mixed with the compost material to prepare compost.

<Example 2>
Carbide produced by-product was obtained by generating electricity from wood derived from Sugi with a woody biomass gasification power generation device. 400 g of the obtained carbide was immersed in a 10 L aqueous solution of ferric sulfate (II) (iron content 11%) at a gauge pressure of −0.09 MPa at room temperature for 10 minutes, usually with the atmospheric pressure set to zero. After the immersion, 1000 g of the carbide was dried at 105 ° C. for 24 hours, and further heated at 700 ° C. for 3 hours in the presence of nitrogen and carbon monoxide gas to reduce the carried ferric sulfate (II). An iron-containing carbide B was obtained.

A sewage sludge dewatering separation solution was passed through a column packed with 2 kg of iron-containing carbide B at a flow rate of 2 L / day for 4 days. The sewage sludge dehydration separation liquid used here is a filtrate obtained by centrifuging the sludge at a sewage treatment plant in Kanagawa Prefecture. As a result, the iron-containing carbide adsorbed phosphorus in the filtrate, and iron-phosphorus-containing carbide B was formed.

After that, the iron-phosphorus-containing carbide B on which phosphorus was adsorbed was naturally dried. Then, the iron-phosphorus-containing carbide B was mixed with the compost material to prepare compost.

[Ratio of iron and phosphoric acid contained in iron-phosphorus-containing carbides]
The results of evaluation of the iron-phosphorus-containing carbide A and the iron-phosphorus-containing carbide B prepared under the above conditions using ICP emission spectroscopic analysis, and the absorption of ammonium vanadomolybdenum acid. Table 1 shows the results of evaluation using the photometric method.

The "total amount of iron (T-Fe)" and "soluble iron (S-Fe)" shown in Table 1 are the results of evaluation using ICP emission spectroscopic analysis, respectively. "Total amount of phosphoric acid (TP)" and "soluble phosphoric acid (SP)" are the results of evaluation using the ammonium vanadomolylate absorptiometry method, respectively. "S-Fe / T-Fe" is the ratio of soluble iron to the total amount of iron, and "TP / T-Fe" is the ratio of the total amount of phosphoric acid to the total amount of iron. The total amount of iron (T—Fe) corresponds to the total amount of the iron component of the present specification, and the total amount of phosphoric acid (TP) corresponds to the total amount of the phosphoric acid component of the present specification.

According to this example, an iron-phosphorus-containing carbide which is a soluble iron in which 5% or more of the iron component is dissolved in a Petermann citrate solution was prepared. The compost using any of the iron-phosphorus-containing carbides of Examples 1 and 2 can continuously suppress the generation of hydrogen sulfide when used in a paddy field.

Claims (13)

Compost containing carbides and iron-containing substances,
The ratio of the iron component of the iron-containing substance to the solid content of the compost is 1% by weight or more and 30% by weight or less.
A compost in which 5% or more of the iron component is soluble iron dissolved in a Petermann citrate solution. Contains phosphoric acid bound to the iron component
The compost according to claim 1, wherein the ratio of the phosphoric acid component of the phosphoric acid to the iron component is 0.2 or more. The compost according to claim 1 or 2, wherein 0.5% or more and 5% or less of the iron component is water-soluble iron that is soluble in water. The compost according to any one of claims 1 to 3, wherein the ratio of nitrogen to the solid content is 1% by weight or more and 21% by weight or less. The compost according to any one of claims 1 to 4, wherein the ratio of potassium to the solid content is 1% by weight or more and 21% by weight or less. The compost according to any one of claims 2 to 5, wherein the ratio of the phosphoric acid component to the solid content is 1% by weight or more. The compost according to claim 6, wherein the ratio of water-soluble phosphoric acid dissolved in water to the solid content is 0.01% by weight or more. The compost according to claim 6 or 7, wherein the ratio of soluble phosphoric acid dissolved in the Petermann citrate solution to the solid content is 1% by weight or more. Any one of claims 1 to 8, wherein the ratio of ash to the solid content is 5% by weight or more and 30% by weight or less, and the ratio of organic carbon to the solid content is 10% by weight or more and 40% by weight or less. The compost described in. The compost according to any one of claims 1 to 9, wherein the ratio of manganese to the solid content is 0.005% by weight or more and 0.2% by weight or less. The compost according to any one of claims 1 to 10, wherein the ratio of boric acid to the solid content is 1 ppm or more and 50 ppm or less. The compost according to any one of claims 1 to 11, wherein the ratio of zinc to the solid content is 1 ppm or more and 700 ppm or less. The compost according to any one of claims 1 to 12, wherein the proportion of water is 30% by weight or more and 80% by weight or less.

Images