Iron ion supply structure using cast iron, method of manufacturing the same, and alga reef using iron ion supply structure

Abstract

To provide an iron ion supply structure capable of continuously and stably supplying iron ions necessary for growth of phytoplankton and algae at a fixed position in the sea or a river over a long period of time, a method for producing the same, and an alga reef using the iron ion supply structure.SOLUTION: An iron ion supply structure 1a includes a flat cast iron plate 2a and a plurality of cast iron block 3a projecting from the cast iron plate 2a. The cast iron block 3a includes a carbonaceous material 4 having an exposed part exposed from the surfaces of the cast iron block 3a and an embedded part embedded inside the cast iron block 3a. Further, the iron ion supply structure has a cast iron hook 6a on a back surface of the cast iron plate 2a.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an iron ion supply structure capable of continuously supplying divalent iron ions necessary for the growth of phytoplankton, algae, or seaweed to the sea or river over a long period of time, a method for manufacturing the same, and a seaweed reef using the iron ion supply structure. [Background technology]

[0002] There have been concerns about environmental pollution and deterioration on the coast, including a phenomenon known as "isoyake" (shore desertification), and the serious decline in seaweed and the resulting decline in fish and shellfish have dealt a major blow to the fishing and aquaculture industries. Furthermore, river bank construction and repair work have made it difficult for riverweed to grow, leading to problems such as insufficient river purification and the narrowing of fish habitats, which in turn has led to environmental deterioration in the river as a whole. One of the measures to improve these is to use ferrous ions (Fe 2+ A technology has been developed to supply iron (II) to the sea and rivers to promote the growth of phytoplankton, seaweed, and riverweed that live in the sea and rivers. Ferrous ions are absorbed by phytoplankton and seaweed by forming complexes with humic acids such as fulvic acid and humic acid. For example, Patent Document 1 discloses an iron ion eluent that is made by mixing powdered or granular iron and powdered or granular charcoal with a water-soluble binder, solidifying the mixture to form a large number of small lumps, and then solidifying some of the lumps together with a water-insoluble binder. By submerging this iron ion eluent in water, the water-soluble binder in the small lumps that are not solidified with the water-insoluble binder comes into contact with water and dissolves, allowing the charcoal and iron to come into contact with each other one after another, thereby eluting iron ions. This makes it possible to consistently elute iron ions over a long period of time. Furthermore, Patent Document 2 discloses an iron ion elution block in which a perforated steel plate is attached to the surface of a concrete block. When this iron ion elution block is installed in the sea, it is possible to generate iron ions from the perforated steel plate by a reaction between the perforated steel plate and seawater. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5258171 [Patent Document 2] Japanese Patent Application Publication No. 2019-208463 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the invention disclosed in Patent Document 1, the small pieces that are not bound with a water-insoluble binder are quickly washed away in the water when they come into contact with water and dissolve, which may make it difficult to sustain the elution of iron ions at a fixed point. Furthermore, when used on a coast or in a river, the small pieces themselves may be washed away, and the water-insoluble binder that binds them may also be worn or deteriorated by stones, rocks, or organisms or driftwood in the sea or river, making it difficult to sustain the elution of iron ions at a fixed point. Furthermore, the invention disclosed in Patent Document 2 is a concrete block with a steel perforated plate installed on the surface, so iron ions are expected to be eluted at certain points. However, since it is made of steel, iron is oxidized to become divalent iron ions, but then trivalent iron ions (Fe 3+ ) quickly oxidizes to ferric hydroxide (Fe(OH)3), which turns into red rust and peels off. Furthermore, trivalent iron ions do not form complexes with humic acids such as fulvic acid and humic acid, and are not absorbed by phytoplankton or algae, which poses the problem that they may not contribute to promoting the growth of phytoplankton or algae.

[0005] The present invention has been made in response to such conventional circumstances, and aims to provide an iron ion supply structure that can continuously and stably supply iron ions necessary for the growth of phytoplankton and algae at a specified location in the sea or river over a long period of time, a method for manufacturing the same, and a seaweed reef using the iron ion supply structure. [Means for solving the problem]

[0006] In order to achieve the above object, the iron ion supply structure of the first invention comprises a flat cast iron plate and a plurality of cast iron blocks protruding from the cast iron plate, wherein the cast iron blocks comprise a carbonaceous material having an exposed portion exposed from the surface of the cast iron block and an embedded portion embedded inside the cast iron block. In the iron ion supply structure configured as described above, divalent iron ions are eluted from the cast iron plate and cast iron block. However, compared to steel structures, cast iron contains approximately 2.5-3% by weight of graphite, which does not rust and therefore is less susceptible to corrosion. The ferrous ions are gradually eluted as divalent iron ions into seawater or river water (hereinafter, seawater and river water are collectively referred to as "water," and sometimes seawater and river water are collectively referred to as "water"). Furthermore, because corrosion does not progress, the structure has excellent corrosion resistance and functions to continuously and stably supply divalent iron ions over a long period of time.

[0007] In addition, an iron-carbon battery is formed between the buried carbonaceous material and the cast iron block, and electrons are released from the cast iron, generating divalent iron ions. The released electrons move from the buried carbonaceous material to the exposed part and are released into the water, or are released into the water through the gap between the buried part and the cast iron block, and the divalent iron ions dissolve into the water through the gap between the buried part and the cast iron block. It is thought that the buried parts of the carbonaceous material will gradually chip and decay, releasing them into the water, and water will seep into the depressions that are created, which will also act to dissolve divalent iron ions into the water. In this application, cast iron includes both gray cast iron containing flake graphite and ductile cast iron containing spheroidal graphite. Furthermore, carbonaceous materials are a concept that includes bamboo charcoal, wood charcoal, and coke.

[0008] The iron ion supply structure of the second invention is characterized in that, in the first invention, a hook is provided on the surface of the cast iron plate on the side where the cast iron block does not protrude. The hook of the iron ion supplying structure having the above-described configuration acts so as to be able to be hooked onto a cage-like structure, a lattice-like structure, or the like.

[0009] The third invention, a method for manufacturing an iron ion supply structure, is characterized by comprising the steps of: producing a vanishing mold having a flat vanishing plate, a plurality of vanishing blocks protruding from the vanishing plate, and a vanishing runner for pouring cast iron; embedding carbonaceous material so that the vanishing mold has exposed portions exposed on the surfaces of the plurality of vanishing blocks and buried portions buried inside the vanishing blocks; covering the vanishing mold with a sand mold while exposing the tips of the vanishing runners of the vanishing mold; pouring the cast iron from the tips of the vanishing runners; cooling the poured cast iron; and peeling off the sand mold. In the method for manufacturing an iron ion supply structure having the above configuration, the vanishing block of the vanishing mold acts to allow the carbonaceous material to be embedded, and acts to promote the formation of exposed and embedded portions of the carbonaceous material in the cast iron block.

[0010] The fourth invention, a seaweed reef, is characterized by having a cage-like structure formed by connecting and closing multiple lattice-like sides, and the iron ion supply structure of the second invention, with the hooks of the iron ion supply structure hooked onto the sides. The algae reef having the above-mentioned configuration acts to hook the iron ion supply structure of the second invention equipped with a hook, and promotes the elution of divalent iron ions around the cage-like structure. The term "cage-like structure" refers to a structure in which multiple lattice-like sides are connected together to form a closed structure, and includes structures without a lid or bottom. A closed structure refers to a structure in which the ends are not open, for example, in a U-shape around the circumference, but are continuous like a square. Therefore, it does not need to be closed with six sides like a cube, and it is not always necessary to have a top or bottom surface.

[0011] The seaweed reef of the fifth invention is the fourth invention, characterized in that a porous concrete plate equipped with a hook is hung on the side surface. In the seaweed reef of the above configuration, the hooks of the porous concrete plate act to be able to be hung on the basket-like structure, and the porous concrete plate acts as a bed attachment device, promoting the attachment of algae. [Effects of the Invention]

[0012] The iron ion supply structure of the first invention has excellent corrosion resistance and can supply divalent iron ions continuously and stably over a long period of time. In addition, divalent iron ions can be supplied from the gap between the cast iron block and the embedded carbonaceous material, and since a recess is generated in the cast iron block even after the carbonaceous material disappears, it is possible to increase the contact area with water and increase the amount of divalent iron ions that are eluted. Furthermore, the iron ion elution structure itself is made of cast iron and is heavy, so once installed it is unlikely to be washed away in the sea or river, making it possible to continue supplying divalent iron ions at a fixed location.

[0013] The iron ion supply structure of the second invention is equipped with a hook that allows the cast iron plate to be hung on a lattice-like structure or a cage-like structure, making it possible to stably stand the cast iron plate in the vertical direction. Therefore, the cast iron block can be protruded perpendicular to the vertical direction from the cast iron plate, and the cast iron block faces the water flow in water, allowing more ferrous ions to be eluted.

[0014] The third invention, a manufacturing method of an iron ion supply structure, uses an evaporative mold, which makes it possible to embed carbonaceous material in a cast iron block, and to form both an exposed portion and an embedded portion between the carbonaceous material and the cast iron block. As a result, the cast iron in contact with the embedded portion releases electrons and becomes divalent iron ions. The electrons move from the embedded portion of the carbonaceous material to the exposed portion and are released into the water, or are released into the water from the gap between the embedded portion and the cast iron block, and the divalent iron ions are eluted into the water from the gap between the cast iron and the embedded portion.

[0015] The algae reef of the fourth invention can be placed facing the water current underwater by hanging the iron ion supply structure on the lattice-like side of the cage-like structure via a hook, and can also protect the algae growing inside the cage-like structure from the water current while dissolving more divalent iron ions near the cage-like structure. Furthermore, because the iron ion supply structure is equipped with a hook and is detachable, the number and arrangement of the iron ion supply structures can be freely set depending on the size of the cage-like structure, the underwater environmental conditions, and the growth conditions of the algae, making it possible to create an algae reef with a high degree of freedom.

[0016] The fifth invention, the algae reef, has a porous concrete plate equipped with a hook in addition to the iron ion supply structure, which can be attached to the lattice side of the basket-like structure, allowing the porous concrete plate to function as a bed for algae, and it is possible to form a seaweed bed not only inside the basket-like structure but also on the lattice side. Also, the algae that have grown on the porous concrete plate can be removed from the cage-like structure along with the porous concrete plate, and the rest can be transplanted to create a new seaweed bed. Furthermore, since the porous concrete plate also has hooks, it is possible to achieve the same function as that achieved by the iron ion supply structure based on the hooks. [Brief explanation of the drawings]

[0017] [Figure 1] 1A is a perspective front view of an iron ion supply structure according to an embodiment of the present invention, and FIG. 1B is a perspective rear view thereof. [Figure 2] 1 is an image of a prototype of an iron ion supply structure according to an embodiment of the present invention. [Figure 3] FIG. 2 is a flow diagram of a method for manufacturing an iron ion supply structure according to an embodiment of the present invention. [Figure 4] 1A is a plan view of a lost mold used in manufacturing an iron ion supply structure according to an embodiment of the present invention, and FIG. 1B is a cross-sectional view taken along line AA in FIG. 1A. [Figure 5]1 is an image of a prototype of a lost mold used in manufacturing an iron ion supply structure according to an embodiment of the present invention. [Figure 6] FIG. 2 is a cross-sectional conceptual diagram showing a state in which an evaporative mold is covered with a sand mold in a manufacturing method of an iron ion supply structure according to an embodiment of the present invention. [Figure 7] 1 is a conceptual diagram of the outer shape of a seaweed reef according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] An iron ion supply structure according to an embodiment of the present invention will be described below with reference to FIGS. Fig. 1(a) is a perspective front view of an iron ion supply structure according to an embodiment of the present invention, (b) is a perspective rear view, and Fig. 2 is an image of a prototype of the iron ion supply structure according to the embodiment of the present invention. In these figures, the iron ion supply structure 1a is formed by dividing a roughly rectangular, flat cast iron plate 2a made of cast iron into nine sections, and forming a cast iron block 3a protruding from the cast iron plate 2a in each section. The cast iron block 3a and the cast iron plate 2a are integrally formed. In addition, a carbonaceous material 4 is embedded in the cast iron block 3a, with a portion exposed.

[0019] The prototype of the iron ion supply structure 1a in Figure 2 uses gray cast iron (material code: FC200) and contains approximately 2.5-3% graphite (carbon). In addition to gray cast iron, ductile cast iron may also be used. Cast iron contains approximately 2.5-3% graphite (carbon), which is more carbon than steel. This slows corrosion and allows time for divalent iron ions to transform into trivalent iron ions. Therefore, iron ions are easily absorbed by fulvic acid and humic acid as divalent iron ions without forming red rust (Fe(OH)3), making them a nutrient source for phytoplankton and algae. In other words, the iron ion supply structure 1a can continuously supply divalent iron ions over a long period of time without corrosion. Furthermore, since the iron ion elution structure 1a is made of cast iron and is heavy, it is unlikely to be swept away by ocean currents or water currents even when installed in the sea or river, and it is not easily deformed and is highly durable, so once installed it can remain in place for a long period of time, which also makes it possible to continuously supply divalent iron ions for a long period of time. The carbonaceous material 4 may be any of coke, charcoal, and bamboo charcoal, and is not particularly limited as long as it is mainly composed of carbon. 2 are optional components that allow the cast iron block 3a to be divided into smaller pieces. Also, two cast iron hooks 6a are provided on the backside of the cast iron plate 2a, one at the top and one at the bottom, approximately in the center, but these are also optional components. The number, arrangement, and width of the cast iron hooks 6a depend on the weight of the iron ion supply structure 1a and the area of the cast iron plate 2a, so they should be designed according to the weight, shape, and required durability of the iron ion supply structure 1a.

[0020] Next, a method for manufacturing the iron ion supply structure according to this embodiment will be described with reference to FIGS. Fig. 3 is a flow diagram of a method for manufacturing an iron ion supply structure according to an embodiment of the present invention. In Fig. 3, components related to each process (step) are indicated by leading lines and symbols, and these symbols are commonly used for the components shown in other drawings. 3, step S1 of the manufacturing method of the iron ion supply structure is a process of producing an evaporative mold 1b. The evaporative mold 1b is made of expanded polystyrene (expanded polystyrene) and disappears at the temperature of molten cast iron (1150-1400°C).

[0021] The structure of the lost mold 1b will be described with reference to Fig. 4. Fig. 4(a) is a plan view of the lost mold used when manufacturing an iron ion supply structure, and Fig. 4(b) is a cross-sectional view taken along line AA in Fig. 4(a). Figs. 4(a) and (b) show the state after a carbonaceous material 4 made of coke is fitted into the lost mold 1b in step S2 of the manufacturing method of an iron ion supply structure. The vanishing mold 1b basically has the same structure as the iron ion supply structure 1a, and at the stage of step S1, there is no carbon material 4 in Figures 4(a) and (b), and nine vanishing blocks 3b protrude from the surface of the flat vanishing plate 2b in three columns and three columns, and vanishing runners 7 are installed at the ends. In the iron ion supply structure 1a, the vanishing plate 2b becomes the cast iron plate 2a, and the vanishing block 3b becomes the cast iron block 3a. Since molten cast iron is poured from the tip 8 of the vanishing runner 7, the height of the tip 8 from the surface of the vanishing plate 2b must be such that the upper end of the carbonaceous material 4 is hidden by the sand mold, or at least the upper surface of the vanishing block 3b is covered by the sand mold.

[0022] 4(a) and (b), the lower part of the carbonaceous material 4 is fitted into the vanishing block 3b, and the upper part is embedded so that it is exposed from the surface of the vanishing block 3b. Therefore, when cast iron is poured into the vanishing mold 1b from the vanishing runner 7 to manufacture the iron ion supply structure 1a, the part of the carbonaceous material 4 embedded in the vanishing block 3b in FIG. 4(b) becomes the embedded part 4b, and the exposed part of the carbonaceous material 4 becomes the exposed part 4a. A vanishing hook 6b is formed on the back side of the vanishing plate 2b, and in the iron ion supply structure 1a, it becomes a cast iron hook 6a. In the vanishing mold 1b of this embodiment, four carbon materials 4 are arranged at each corner of the vanishing block 3b, but the number, size, and arrangement are not limited to this, and it is desirable to design appropriately according to the area of the upper end of the vanishing block 3b and the required amount of divalent iron ions to be supplied, assuming that the cast iron block 3a of the iron ion supply structure 1a is also used. A prototype of the lost mold 1b produced in step S2 is shown in Figure 5. This prototype is for producing a prototype of the iron ion supply structure 1a shown in Figure 2, and therefore has lost grooves 5b for forming the grooves 5a that were provided in the iron ion supply structure 1a.

[0023] Returning to Figure 3, step S3 is the process of producing a sand mold. Here, an explanation will be provided with reference to Figure 6. Figure 6 is a cross-sectional conceptual diagram showing the state in which the lost mold is covered with a sand mold in the method for producing an iron ion supply structure. In Figure 6, there are two types of sand molds: a lower sand mold 9b that is placed under the lost mold 1b, and an upper sand mold 9a that is placed over the lost mold 1b after the lost mold 1b is placed on the lower sand mold 9b. Before both the lower sand mold 9b and the upper sand mold 9a are molded as sand molds, a liquid binder (hardener) is added to harden the sand and kneaded to create viscosity. In step S3, the upper sand mold 9a is first produced and shaped to a size large enough to accommodate the lost mold 1b, and the lost mold 1b is then placed on top of it and fixed in place. In this step S3, the lost mold 1b is installed with the lost hook 6b buried in the lower sand mold 9b as shown in Figure 6, but the upper sand mold 9a does not yet exist as it will cover the lost mold 1b in the next step S4. After fixing the lost mold 1b to the lower sand mold 9b, step S4 is carried out, in which the lost mold 1b is covered with the upper sand mold 9a. At this time, the work is carried out carefully so that the upper sand mold 9a covers the periphery of the carbonaceous material 4 of the lost mold 1b without any gaps, and also while taking care not to break the erected lost runner 7. Note that the tip 8 of the lost runner 7 of the lost mold 1b is exposed from the upper sand mold 9a. The state at the completion of step S4 performed in this manner is shown in FIG.

[0024] In step S4, after the upper sand mold 9a and the lower sand mold 9b have hardened, step S5 is carried out, in which molten cast iron is poured from the tip 8 of the vanishing runner 7. In this step, the molten cast iron vanishes the polystyrene foam vanishing mold 1b, and the cast iron flows into the mold, forming the iron ion supply structure 1a. The carbonaceous material 4 embedded in the vanishing block 3b does not disappear, but is formed so as to be embedded in the cast iron block 3a in place of the vanishing block 3b. Step S6 is a cooling process for the iron ion supply structure 1a. The cooling method can be to leave it covered with the upper sand mold 9a and the lower sand mold 9b at room temperature (natural drying), or it can be cooled with a fan. The cooling time depends on the size and thickness of the iron ion supply structure 1a, but it takes about 6 to 10 hours by natural drying. Step S7 is a step of peeling off the upper sand mold 9a and the lower sand mold 9b to remove the iron ion supply structure 1a. The cast iron that has flowed into the vanishing runner 7 remains in the removed iron ion supply structure 1a, so that portion is cut away. In this way, the iron ion supplying structure 1a is manufactured.

[0025] In the manufacturing method of the iron ion supply structure according to this embodiment, by embedding carbonaceous material 4 in the vanishing block 3b of the vanishing mold 1b, it is possible to hold the carbonaceous material 4 in the cast iron block 3a in place of the vanishing block 3b that has been vanished by the cast iron, and the carbonaceous material 4 can have an embedded portion 4b and an exposed portion 4a between the cast iron block 3a and the carbonaceous material 4. In the iron ion elution structure 1a, the carbonaceous material 4 has an embedded portion 4b and an exposed portion 4a, so that an iron-carbon battery is formed between the embedded portion 4b of the carbonaceous material 4 and the cast iron block 3a, electrons are released from the cast iron to generate divalent iron ions, the released electrons move from the embedded portion 4b of the carbonaceous material 4 to the exposed portion 4a and are released into the water, or are released into the water from the gap 3a between the embedded portion 4b and the cast iron block, and the divalent iron ions are eluted into the water from the gap between the embedded portion 4b and the cast iron block 3a. The eluted divalent iron ions combine with humic acids such as fulvic acid and humic acid and can be absorbed by phytoplankton, algae, and seaweed to serve as a nutrient source. Furthermore, it is thought that the buried portion 4b of the carbonaceous material 4 will gradually chip and decay and be released into the water, and water will penetrate into the recesses that are created, dissolving divalent iron ions into the water and similarly becoming a source of nutrients.

[0026] Next, a seaweed reef using the iron ion supply structure according to this embodiment will be described with reference to Fig. 7. Fig. 7 is a conceptual diagram showing the outer shape of the seaweed reef according to this embodiment. In Figure 7, the algae reef 10 is made by combining eight lattice-shaped side panels 11 in two upper and lower rows to form a cage-like structure 12 stacked in two rows in a closed state with a rectangular horizontal cross section, and the cast iron hooks 6a of the iron ion supply structure 1a are hung on the lattices of the side panels 11. In the algae reef 10 of this embodiment, only one iron ion supply structure 1a is hung as a unit on one side panel 11, but multiple iron ion supply structures 1a may be hung, or may be hung on multiple side panels 11. The iron ion supply structures 1a may be arranged in any manner taking into account the water flow. By attaching the iron ion supply structure 1a made of cast iron containing a lot of carbon to the algae reef 10, it takes a long time for divalent iron ions to become trivalent iron ions, making it easier for them to combine with humic acid and making it less likely for red rust to form, making it possible to stably supply divalent iron ions over a long period of time. Furthermore, by providing the iron ion supply structure 1a with a cast iron hook 6a on its backside, it can be easily attached and detached to the cage-like structure 12 made up of side panels 11, and its positioning can be easily changed, allowing for greater freedom in the formation of the seaweed reef 10. Also, by hooking it with the cast iron hook 6a, the iron ion supply structure 1a can be stably erected in the vertical direction, and since the cast iron block 3a protrudes from the cast iron plate 2a perpendicular to the vertical direction, it faces the water flow and can elute divalent iron ions downstream toward the inside of the cage-like structure 12 without stagnation near the cast iron block 3a.

[0027] Furthermore, the number and height of the side panels 11 can be freely adjusted according to the depth of the installation location, and since the algal reef 10 is composed of the side panels 11 and the iron ion supply structure 1a, it can be easily installed in shallow waters using a small vessel and a small number of people, without using heavy machinery. Furthermore, by placing this seaweed reef 10 in shallow waters near the coast, it is possible to supply phytoplankton, algae, or seaweed with nutrients containing ferrous ions, preventing rocky shore denudation and allowing algae and seaweed to grow in the sea near the coast. Not only in the sea, but also in rivers, it can be used in shallow areas by lowering the height of the side panels 11, and can similarly be used as a seaweed reef 10 for riverweed, etc. The material of the side panel 11 is not important, but it is preferable to construct it from metal as it is heavy and less likely to be swept away by ocean currents or water currents. However, steel or cast iron, for example, can also be used. Cast iron in particular is resistant to corrosion without forming red rust, just like the iron ion eluting structure 1a, and is also capable of gradually supplying divalent iron ions. Therefore, in combination with the iron ion eluting structure 1a, it can supply divalent iron ions to phytoplankton, algae, and seaweed in a stable manner over a long period of time. In addition, in this embodiment, the seaweed reef 10 has a structure in which the side panel 11 is closed with a rectangular horizontal cross section, but it is not limited to a rectangular shape as long as it is closed, and it can also be a polygon such as a triangle or a hexagon.

[0028] Furthermore, a porous concrete plate 13 may be installed on the seaweed reef 10. Since this porous concrete plate 13 is made of porous concrete, it functions as a landing device, allowing algae and seaweed to easily grow on its surface. By similarly hanging the porous concrete plate 13 with a hook on the lattice of the side panel 11 near the iron ion supply structure 1a, an environment is created in which nutrients are easily supplied, making it possible to form a seaweed bed in which algae and seaweed can more easily grow. In addition, the algae and seaweed that have grown on the porous concrete plate 13 can be removed along with the porous concrete plate 13 and transplanted to another location, and the plate can also be used as a seedling base for creating new seaweed beds. The porous concrete plates 13 are also units, and their number and arrangement can be freely set. In addition, the seaweed reef 10 according to this embodiment can grow and flourish algae and seaweed, which can attract fish that eat them, making it possible to use it as a fishing reef or spawning ground. [Industrial Applicability]

[0029] The iron ion supply structure of the present invention can dissolve divalent iron ions in the sea or rivers and be used as a nutrient source for phytoplankton, algae, and seaweed, and a seaweed reef equipped with an iron ion supply structure can be used as a place to grow algae and seaweed, a seedling base for creating seaweed beds in other locations, and even as a fishing reef or spawning ground. [Explanation of symbols]

[0030] DESCRIPTION OF SYMBOLS 1a...Iron ion supply structure 1b...Evaporative mold 2a...Cast iron plate 2b...Evaporative plate 3a...Cast iron block 3b...Evaporative block 4...Carbon material 4a...Exposed portion 4b...Buried portion 5a...Cast iron groove 5b...Evaporative groove 6a...Cast iron hook 6b...Evaporative hook 7...Evaporative runner 8...Tip portion 9a...Upper sand mold 9b...Lower sand mold 10...Seaweed reef 11...Side panel 12...Cage-like structure 13...Porous concrete plate

Claims

1. An iron ion supply structure comprising a flat cast iron plate and a plurality of cast iron blocks protruding from the cast iron plate, wherein the cast iron blocks have a carbonaceous material having an exposed portion exposed from the surface of the cast iron block and an embedded portion embedded inside the cast iron block.

2. 2. The iron ion supply structure according to claim 1, wherein a hook is provided on a surface of the cast iron plate on the side where the cast iron block does not protrude.

3. A method for manufacturing an iron ion supply structure, comprising: a step of producing a vanishing mold having a flat vanishing plate, a plurality of vanishing blocks protruding from the vanishing plate, and a vanishing runner for pouring cast iron; a step of embedding carbonaceous material so that the vanishing mold has exposed portions exposed from the surfaces of the plurality of vanishing blocks and embedded portions embedded inside the vanishing blocks; a step of covering the vanishing mold with a sand mold while exposing the tips of the vanishing runners of the vanishing mold; a step of pouring the cast iron from the tips of the vanishing runners; a step of cooling the poured cast iron; and a step of peeling off the sand mold.

4. A seaweed reef comprising a cage-like structure formed by connecting and closing multiple lattice-shaped sides, and the iron ion supply structure described in claim 2, wherein the hooks of the iron ion supply structure are hooked onto the sides.

5. 5. The seaweed reef according to claim 4, characterized in that a porous concrete plate equipped with a hook is hung on the side surface.

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