JP2003134958A - Method for promoting co2 absorption in ocean using iron and steel slag - Google Patents

Abstract

PROBLEM TO BE SOLVED: To grow phytoplanktons existing in the sea by eluting inorganic nutrient salts contained in granular or small lump iron and steel slag by an aqueous solution reaction, to reduce CO2 in the surface layer water of the sea and in its turn to absorb and fix CO2 in the air. SOLUTION: The actual condition survey of nutrient salts in an applied sea area is taken into account and the demand ratio of nutrient species requirement (e.g. nitrogen, phosphorus, silicon, iron) of planktons to be cultured is calculated. Components, particle size, specific gravity, or the like, of charging slag corresponding to the demand ratio are designed so that nutrient species concentration necessary for culture is secured, Diatomaceae which are liable to settle and connected to the upper food chain are proliferated, CO2 in the air is fixed, propagation of harmful planktons to cause a red tide, or the like, is controlled and the environment of water area is restored.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to phytoplankton which promotes absorption of CO ₂ by photosynthesis without causing harmful phenomena such as red tide, and in particular, by growing and culturing diatom plankton which easily leads to higher production. Regarding the method of promoting CO ₂ absorption, in particular, effective use of waste and basic production in the ocean by using steel slag or its combination with municipal wastewater rich in nitrogen salt as nutrient salt for plankton breeding expansion of marine resources by phytoplankton to support, further, CO ₂ by sedimentation into the seabed of organic carbon absorbed by phytoplankton
It is a technology that contributes to the restoration of the global environment by fixing CO ₂ and reducing CO ₂ in the ocean and eventually in the atmosphere.

[0002]

2. Description of the Related Art A technique of utilizing steel slag for propagating algae in the ocean is known. For example, Japanese Patent Publication 57-24094
In the gazette, steelmaking slag is cast into a mold and used as a fish reef to suppress the generation of methane gas and hydrogen sulfide by the action of the steelmaking slag as an oxidant. It has been described to promote the growth of species. Further, as a method for treating steelmaking slag used for fish reefs, etc., there have been many applications for a method of solidifying CaCO ₃ produced by carbonation solidification treatment as a binder (JP-A-11-71).
No. 160 bulletin).

[0003]

However, all of these methods use steel slag in a block form or block form and deposit it in the ocean to utilize it as a fish reef. Propagation of phytoplankton, especially diatoms For the purpose, there is no known technique for spraying and suspending slag in coastal areas and the ocean. In addition, since the steel slag does not contain nitrogen, a breeding method that considers even the balance of nutrient salts in the sea area where nitrogen as a nutrient is insufficient has not been developed.

That is, in the conventional method using steel slag,
Nutrient salts for phytoplankton cannot be continuously and stably supplied to a wide range of sea areas at required concentrations. For example, in the method of forming into a block shape and using it as a fish reef, the concentration of nutrients can be increased locally, but the concentration sharply decreases offshore away from the block, so it is not possible to have a wide range of effects. Can not. In order to solve these problems, it may be possible to place blocks in the entire applicable sea area in order to increase the concentration of nutrients in a wide range, but this is not feasible from the viewpoints of marine use such as fishing grounds and economics.

Also, from the viewpoint of nutrient salts necessary for the growth of algae, the composition and concentration of nutrient salts differ greatly in each sea area depending on the temperature, ocean current and other conditions, and nitrogen salts are abundant. The sea area where iron is insufficient,
In some areas, all nutrients, including nitrogen salts, are deficient. In this way, in sea areas where the composition and concentration of nutrients are different,
It is necessary to supply deficient nutrient salts corresponding to that, but for example, in the case of supplying only uniform components such as the addition of steelmaking slag alone, deficient nutrient salts will not be appropriately supplied according to the applicable sea area, and a satisfactory plant Plankton growth does not occur.

[0006] Further, the supply of artificial nutrient salts to the ocean, including the inflow of inorganic waste liquid into the coastal areas, may generally destroy the balance of the natural world and cause abnormal phenomena such as red tide. When applying salt, it is necessary to give due consideration to environmental aspects.

The present invention has been made in view of such circumstances.
Therefore, without inducing abnormal growth such as red tide,
Increase phytoplankton especially while avoiding abnormal increase in pH
Develop technology to safely and continuously supply nutrient salts for breeding
And phytoplankton CO ₂Promoting absorption
Causes CO in the ocean and eventually in the atmosphere₂To reduce
It is to provide a method that can.

[0008]

[Means for Solving the Problems] The CO ₂ absorption promoting method according to the present invention, which has been able to solve the above problems, is suitable for the growth of plankton based on the results of a survey on the actual condition of nutrient salts for phytoplankton in the applicable sea area. In consideration of the required ratios of various nutrients, supplement the insufficient nutrients by adding or spraying powdery or granular slag steel slag to the sea area to grow phytoplankton existing in the sea area.
It is characterized by promoting the absorption of CO ₂ .

The steel slag used in the present invention has a high
Furnace slag, hot metal pretreatment slag, converter slag, electric furnace slag
Rug, smelting reduction furnace slag, secondary refining slag, stainless steel
Various slags such as slag are used individually or in appropriate combinations of two or more.
Although they can be used in combination, it is preferable that the internal component and
Then, 2CaO ・ SiO₂To 3CaO ・ P₂O_FiveA solid solution phase, 3CaO ・ Si
O ₂, 3CaO / P₂O_Five2CaO ・ SiO₂A solid solution phase, 4CaO ・ P₂O_Five,
And at least one of FeO
1 or more depending on the type of undernourished salt in the region
Those including the above are used. Especially, the present invention is suitable for the open sea area.
When used, most of the open ocean is oligotrophic, so the above selection
Those containing all of the components are preferably used. Well
In addition, two or more kinds of steel slag with different composition are properly assembled.
Combined, the ratio of nutrients eluted from those steel slags
Can be adjusted according to the nutrient requirements of the applicable sea area.
Recommended as a preferred mode for carrying out the invention.

Further, since the steel slag does not contain a nitrogen component which is an essential nutrient for phytoplankton, depending on the area of application, the municipal wastewater and / or the inorganic ammonium salt may be used as a nutrient salt together with the steel slag. It is also effective to do.

Further, in order to efficiently promote the elution of nutrients from the steel slag that has been thrown into or dispersed in the ocean at the surface layer of the applicable sea area, the grain size and specific gravity of the steel slag are adjusted so that the sedimentation rate in seawater is 0.01. It is better to set it to m / sec or less.

Further, in place of the direct spraying of the iron and steel slag, nutrient salts useful for the growth of phytoplankton are extracted in advance from the steel slag as an aqueous solution, and this is sprayed on the applicable ocean to exhibit the same phytoplankton growth effect. It is also included in other embodiments of the present invention.

[0013]

Under the above-mentioned problems, the inventors of the present invention adopt the method of charging or spraying steel slag in the application sea area in the form of powder or granules, and the nutrition contained in the steel slag. We thought that salt could be used more effectively and that the reformed sea area would be expanded and the CO ₂ absorption promotion effect accompanying it would be exhibited more effectively, and we proceeded with research along that line.

The main components of steel slag are CaO, SiO ₂ and A.
It contains l ₂ O ₃ , of which CaO becomes Ca ²⁺ ions and rapidly dissolves in seawater. However, the pH of seawater is Mg
When the solubility limit of (OH) ₂ rises, Mg ²⁺ ions dissolved in seawater in large amounts become Mg (OH) ₂ and precipitate to suppress the rise in pH, so no particular problem occurs. Absent.

Further, the supply of artificial nutrient salts to the ocean has a possibility of destroying the balance of the natural world and causing abnormal phenomena such as red tide as described above, but it is eluted from the steel slag as described later. Si preferentially promotes the growth of diatom plankton among phytoplankton. It has been confirmed that the diatom plankton does not easily become a red tide-generating species because it easily connects to the upper part of the food chain and is a useful species that supports the productivity of the sea area from the basics.

[0016] Therefore, in order to multiply phytoplankton existing in the sea, powdery or small lumps of steel slag are used, and nutrient species (eg nitrogen, phosphorus, After roughly estimating the required ratio of (silicon, iron, etc.), if the appropriate component of steel slag is added or sprayed in the applicable sea area,
By supplementing the nutrient species (nitrogen, phosphorus, silicon, iron, etc.) eluted from the slag, the sea area is provided with an environment suitable for the growth of the plankton to be cultured, particularly phytoplankton, that is, a nutritional balance. As a result, the photosynthetic reaction is activated by the growth of phytoplankton in the sea area, the absorption and fixation of CO ₂ in seawater is significantly promoted, and the CO _{2 in} the atmosphere can be greatly reduced.

The embodiments of the present invention will be described in detail below.

Examples of the iron and steel slag used in the present invention include blast furnace slag, hot metal pretreatment slag, converter slag, electric furnace slag, smelting reduction furnace slag, secondary refining slag, and stainless slag. Besides being usable, two or more kinds can be used in combination, if necessary. The iron and steel slag contains phosphorus, silicon, iron, etc., which are nutrient salts of phytoplankton, and can be effectively used as nutrient salts.

However, the mineral morphology is complicated, and the mineral composition to be produced remarkably differs depending on the contained components and the cooling conditions at the time of production, and the elution rate of nutrients into seawater also greatly differs. For example, the elution rate of phosphorus from the 4CaO / P ₂ O ₅ phase containing 16.9 mass% phosphorus is very fast, while the elution rate of phosphorus is 20.0 mass%.
The dissolution rate of phosphorus from the 3CaO ・ P ₂ O ₅ phase containing 3C and 2CaO ・ SiO ₂
The elution rate of phosphorus from the aO ・ P ₂ O ₅ solid solution phase (phosphorus content 2.2 mass%) is almost the same, and the elution amount of phosphorus is only about 1/8 of that in the 4CaO ・ P ₂ O ₅ phase. . Thus, the elution rate and elution amount of useful components in iron and steel slag are greatly influenced by the mineral phase structure of the iron and steel slag.

Therefore, in carrying out the present invention, the elution rate and elution amount of these useful components should be taken into consideration, and the components and cooling rate of the steel slag should be controlled using representative indexes such as basicity and oxidation degree. Therefore, it is desirable to control the useful components to a form that allows easy elution.

In the present invention, as described above, it is possible to appropriately replenish the undernutrient salt according to the characteristics of the sea area, especially the required ratio of the nutrient salt. In terms of necessary nutrient salts, the oceans in the world have significantly different components depending on the temperature, ocean current, and other conditions, and while there are abundant nitrogen salts, sea areas where iron, which is a trace metal element, is insufficient. There are also sea areas where there is a total lack of nutrients including nitrogen salts. For such different conditions, it is necessary to supply nutrient salts corresponding to them, and simply supplying supplementary components may not properly supply the components that control the rate of phytoplankton growth. The purpose of may not be exerted effectively.

Therefore, in carrying out the present invention, in addition to the above-mentioned components of iron and steel slag and the form of existence of the active component, or separately from this, a mixture of a plurality of brands of iron and steel slag is mixed and used to supply phosphorus or iron. By adjusting the (elution ratio) or using a combination of municipal wastewater and inorganic ammonium salts, such as ammonium sulfate and ammonium chloride, as a nitrogen salt replenishment means that cannot be replenished with steel slag, the sea area is required. It is effective to supplement the undernourished salt so that the proper nutrient balance can be obtained.

Looking at the influence of the concentration of nutrient salt, the growth rate of plankton is almost proportional to the concentration of nutrient salt in the low concentration region, but when it exceeds the required concentration, it reaches a saturated state and stabilizes at a constant value. Therefore, it is not necessary to dissolve the supplied steel slag instantaneously to elute the nutrient salts at once, but rather from the viewpoint of suppressing an abnormal increase in pH in the added sea area, the added steel slag is dissolved at an appropriate rate. It is desirable to let For that purpose, it is preferable to control the particle size composition of the steel slag used in the present invention to an average particle size of 10 mm or less, and by using the steel slag having such an average particle size, nutrient salts from the steel slag can be removed. It is desirable to maintain an appropriate dissolution rate and maintain a necessary and sufficient nutrient concentration for a long period of time.

Regarding the problem of pH increase, the pH due to Mg (OH) ₂ is increased by using the steel slag having the above grain size constitution.
The buffer effect of is exerted, and the pH of the added sea area can be controlled to a maximum of about 9.3 or less.

In order to continuously and stably elute the nutrient salt from the iron and steel slag, it is effective to appropriately control the particle size and specific gravity, and to suppress long-term floating on the sea surface and short-term sedimentation, which is preferable. Is a steel slag with an apparent specific gravity of about 2.5 to 3, which is reduced in the apparent specific gravity to about 1.5 or less by subjecting it to void-containing treatment or porosification treatment to settle in seawater. It is desirable to set the speed to 0.01 m / sec or less. Furthermore, as mentioned above, when using multiple brands of slag together, some of them may dissolve quickly due to floating on the sea surface. It is also effective to control the elution rate.

In the above description, the case where the converter slag is put into the ocean in the form of powder or small particles or sprinkled into the ocean has been explained, but as another method that can obtain the same effect, it is possible to grow phytoplankton from steel slag. It is also possible to preliminarily extract the nutrient salt of as an aqueous solution and spray this on the applicable sea area. In this case, by appropriately selecting the type and brand of steel slag used for extraction, the content ratio of nutrient salts in the extract should be adjusted to be a nutrient salt ratio suitable for supplementation of insufficient nutrient salts in the applicable sea area. Alternatively, it is also effective to mix the extract with the municipal wastewater that becomes nitrogen salt in an appropriate ratio and to add or spray the mixture.

[0027]

EXAMPLES The present invention will be described in more detail with reference to the following experimental examples. However, the present invention is not limited by the following experimental examples, and may be appropriately applied within the scope of the above and the following points. Modifications can be made, and all of them are included in the technical scope of the present invention.

Experimental Example First, using artificial seawater, nutrient salts (P, S
The elution characteristics of i) and the required trace metal element (Fe) elution were determined. The composition of the steelmaking slag used is shown in Table 1, and the elution behavior of P, Si, and Fe from each slag is shown in FIGS. The experimental conditions are:
1 g of a slag powder sample of 270 mesh or smaller was added to 0.5 liters of artificial seawater, stirred, and left at room temperature (20 ° C) for 30 days, during which sample seawater was collected every predetermined number of days. Then, changes in the concentrations of P, Si and Fe were observed.

[0029]

[Table 1]

As is clear from FIGS. 1 to 3, the elution concentrations of P, Si and Fe differ considerably depending on the type (composition of components) of the steelmaking slag. It can be seen that the nutrient concentration of water is sufficiently higher than that of water and a sufficient concentration of nutrients can be supplied from the steelmaking slag.

Further, in order to grasp the nutrient salt elution rate due to the difference in crystal phase, 4CaO · P ₂ O ₅ phase containing 16.9 mass% of phosphorus, which is one of the typical compounds in steelmaking slag, and 20.0% of phosphorus.
3CaO · P ₂ O ₅ phase containing mass% and a mineral phase (phosphorus content 2.2 mass%) in which 3CaO · P ₂ O ₅ was solid-solved in 2CaO · SiO ₂ were used, and the elution rate of phosphorus was examined for each. The experimental method was the same as the above method.

The results are shown in FIG. 4, and 4CaO.P ₂ O ₅
Elution of phosphorus from the phase is the fastest and most, whereas 3C
The elution of phosphorus from the aO ・ P ₂ O ₅ phase and the phase in which 3CaO ・ P ₂ O ₅ was solid-solved in 2CaO ・ SiO ₂ was similar, and both were compared with the elution from the 4CaO ・ P ₂ O ₅ phase. Slow and few.

From this, phosphorus is efficiently eluted.
Has 4CaO ・ P₂O_FiveSteelmaking slag with crystallized phases is the most effective
Yes, and 2CaO for steelmaking slag with low phosphorus content
・ SiO ₂To 3CaO ・ P₂O_FiveThe slag that crystallized the mineral phase in which
It turns out to be effective.

Further, when an experiment was conducted on the elution of Si, even if 3CaO.2SiO ₂ or CaO.SiO ₂ exist as a mineral phase, the elution of Si into seawater is difficult to occur, but 3CaO.SiO ₂ or 2Ca
It was confirmed that Si was easily dissolved in seawater when O · SiO ₂ was added in the steelmaking slag.

Next, in order to confirm the effect of the steel slag on the growth of phytoplankton, 5 liters of seawater from Sendai New Port was sampled, and steelmaking slag was crushed to have an average particle size of 5 to 20 μm as nutrient salts of phytoplankton. Quantification of phytoplankton growth by adding 0 to 200 mg of P, Si and Fe per liter and 0 to 40% by volume of municipal wastewater (including nitrogen salts) and measuring the fluorescence of chlorophyll a. did.

The dephosphorization slag used in this experiment was performed on all the slags shown in Table 1 above, and the main components of the decarburization slag are as follows.

Decarburized slag composition (mass%) SiO ₂ : 13.8%, CaO: 44.3%, Al ₂ O ₃ : 1.5%,
MgO: 6.4%, MnO: 5.3%, T-Fe: 17.5%.

The results are as shown in FIG. 5. The growth of phytoplankton does not change even if only urban wastewater is added as the nitrogen salt. However, when slag is added thereto in an amount of 20 mg / l or 200 mg / l, the growth does not increase. It has been significantly increased, and it can be confirmed that the combined use of slag significantly promotes the growth of phytoplankton by nitrogen salts derived from municipal wastewater.

Furthermore, in order to understand the effect of addition of steel slag on the characteristics of each seawater, the warm water mass formed in the Sanriku sea area
(A part of the Kuroshio Extension was broken and moved to the north), and 0.9-1.0 liters of the experimental sample water were collected from a depth of 5 m from the sea surface in the peripheral part of the warm water mass. A similar phytoplankton growth experiment was performed. It should be noted that the warm water mass lacks all nutrient salts, reflecting the characteristics of the oligotrophic Kuroshio,
The peripheral portion is an example in which nutrient salts other than iron are relatively rich in content.

The results obtained when 0 to 80 ml of the eluate from the steelmaking slag and 0 to 4 μM (micromoles) of ammonia water as a substitute for the municipal waste water were individually added to 0.9 liters of warm water mass are shown in FIG. It shows in FIG. As is clear from these figures, the addition of slag alone does not have a proliferative effect (FIG. 6). On the other hand, for ammonia water, the proliferative effect was slightly improved by increasing the amount of addition, which indicates that the sea area is nitrogen-limited (lack of nitrogen).

On the other hand, 0 to 80 ml of slag eluate (Fe content: about 7 to 30 μg / liter) was added to 0.9 liters of seawater around the warm water mass that was iron-limited (iron deficiency), and the same. When a phytoplankton breeding experiment was carried out, it was confirmed that, as shown in FIG. 8, the effect of adding the steelmaking slag eluate containing a large amount of iron was remarkable.

From these results, steel slag is selected so as to be able to supply an appropriate nutrient salt according to the characteristics of each seawater, and when the seawater is deficient in nitrogen salt, urban wastewater is added in combination. By doing so, it can be confirmed that a high proliferative effect is exerted on phytoplankton.

By the way, in the ocean, the depth at which light reaches and photosynthesizes by phytoplankton varies depending on the situation, but it is generally considered to be about 100 m. Therefore, it is desirable that the nutrient salts be sufficiently eluted while the slag is settling in this depth range. Therefore, when we examined the preferred sedimentation velocity by diffusion simulation that considered the elution of nutrients, if the sedimentation velocity was set to 0.01m / sec or less, the nutrients were sufficiently eluted during the sedimentation process up to the depth where light reached. It was confirmed to do.

Further, it is possible to make the apparent specific gravity of the steel slag smaller than that of seawater and continuously elute the nutrient salts in a floating state, and it is also possible to produce a slag having an apparent specific gravity of about 0.5 to 0.9. Such a steel slag having a small apparent specific gravity is a hollow slag or a spherical slag containing closed cells, and its typical characteristics are as follows.

Chemical composition (mass%) ... CaO: 48%, SiO ₂ : 43%, Al ₂ O ₃ : 4%, F: 5% Grain size composition (mass%): 425-850 μm: 46%, 250-425 μ
m: 39%, 180-250 μm: 9%, 150-180 μm: 1.5%, 100
-150μm: 3%, 100μm or less: 1.5% Specific gravity 0.75-0.89

Next, from the above effects of the present invention, the CO ₂ absorption is calculated on the basis of the numerical indexes described below, and the results are as follows.

The maximum CO ₂ absorption capacity by phytoplankton expected when the nutritional balance is adjusted is 2 kg / m ² / year in terms of carbon, and the mass ratio of C and Fe required for phytoplankton growth is C It is believed that: Fe = 1273: 0.06. Therefore, the amount of iron source necessary for the growth of phytoplankton to achieve CO ₂ uptake of ² kg / m ² / year in terms of carbon is 0.094 g / m ² /
The amount of slag required to elute the iron source from the steelmaking slag is 1.25 kg / m ² / year (However, iron content: 13.4%,
Elution efficiency: 0.00056).

Using the above value, which is one of the typical values obtained from the above test results, the effect is estimated for the individual cases described below (in each sea area, iron is often the rate-determining agent, so iron-based It is as follows.

The amount of nitrogen newly added to the coastal areas of Japan every year due to the inflow of polluted river water is 36
The amount is 0,000 tons, which causes the nutrient salt balance to be lost, causing red tides and other damage in various places. But,
If steel slag is added to the coastal sea area to adjust the nutrient salt balance using the present invention, it becomes possible to preferentially multiply diatom plankton that supports higher-order production, which can contribute to restoration of the coastal environment.

In order to grow up while photosynthesizing phytoplankton by using up excess nitrogen salts, when the elution efficiency of iron is 0.00056, approximately 13 million tons / year of steelmaking slag is required (elution efficiency of 1 In case of, 7,200 tons /
Annual steelmaking slag is required) and the so-called redfield ratio (C: N: Fe = 1273: 224: 0.06) is used, the amount of carbon that can be absorbed is about 20 million tons / year, ₂ Equivalent to about 6% of emissions.

Subarctic North Pacific, Eastern Tropical Pacific, South
Most high seas, such as the polar waters, are known as HNLC (High Nitrate).
Low Chlorophyll) sea area with high nutrient concentration but plants
It is a sea area with a small amount of plankton production. Iron here
Controls phytoplankton growth, 10,000 km²Sea of
2 kg / m for phytoplankton in the area²Can achieve C immobilization / year
The amount of steelmaking slag required to demonstrate the
Per year. Also CO ₂2 for carbon immobilization
0 megatons / year, which is CO in the steel industry₂Emissions
(Fiscal 1997: 47 megatons of carbon equivalent) Approximately 43% of the amount
Becomes

If the applicable sea area is further expanded, it can be fixed.
CO₂The amount of is further increased. By the way, 500,000km²Sea area
The technology of the present invention is suitable for (much smaller than the area of the Sea of Japan).
If used, it is possible to fix carbon of 1 gigatons / year.
This is the annual CO ₂Equivalent to about 3 times the amount emitted
CO₂Enables fixing of.

[0053]

The present invention is configured as described above,
By inputting or spraying a large amount of steel slag discharged in the steelmaking and steelmaking fields into the ocean in the form of powder or granules, and effectively utilizing the nutrient salts contained in the steel slag for the growth of marine phytoplankton, CO ₂ in seawater and eventually in the atmosphere can be efficiently absorbed and fixed without pollution without causing marine pollution such as red tide and deterioration of fishing grounds, reducing CO ₂ which is a cause of global warming A dramatic effect can be expected.

Further, in the present invention, the steel slag, which is a large amount of by-product in the steel manufacturing process and is mostly treated as waste, can be effectively used as a valuable resource, and further, when the municipal wastewater is used as the nitrogen salt. However, due to the action of steel slag, it can be effectively utilized as nitrogen salt in the applicable sea area, and it is possible to prevent marine pollution due to municipal wastewater.

[Brief description of drawings]

FIG. 1 is a graph showing the amount of P eluted from steelmaking slag.

FIG. 2 is a graph showing the amount of Si eluted from steelmaking slag.

FIG. 3 is a graph showing the elution amount of Fe from steelmaking slag.

FIG. 4 is a graph showing the elution behavior of P from each mineral phase in slag.

FIG. 5 is a graph showing the phytoplankton growth effect by the addition of steelmaking slag.

FIG. 6 is a graph showing the phytoplankton growth effect when slag is added to warm water mass.

FIG. 7 is a graph showing the phytoplankton growth effect when ammonia water is added to the warm water mass as a substitute for urban wastewater.

FIG. 8 is a graph showing the phytoplankton growth effect when slag eluate is added around the warm water mass.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ identification code FI theme code (reference) C21C 5/54 C21C 5/54 7/00 7/00 J (72) Inventor Tamiji Yamamoto Higashihiroshima, Hiroshima Prefecture 1-4-4 Ichikagayama Hiroshima University (72) Inventor Masao Minamikawa 5th Kita-jo Nishi, Kita-ku, Sapporo-shi, Hokkaido F-term inside Hokkaido University (reference) 2B104 CA01 EF09 4K013 CF01 4K014 AE01 4K070 AB11 BC12

Claims (7)

[Claims] 1. Based on the results of a nutritional salt fact-finding survey on phytoplankton in the applicable sea area, taking into account the required ratio of nutrients suitable for the growth of the plankton, the insufficient nutrients are provided in the form of powder or granules in the sea area. the compensated after the input or dusting of iron and steel slag, CO ₂ absorption-promoting methods in the ocean, characterized in that grown phytoplankton present in the waters to facilitate the absorption of CO _2. 2. A steel slag containing 2CaO.SiO ₂ and 3CaO.P ₂
Phase O ₅ is dissolved, using a steel slag containing a _{3CaO · SiO 2, 3CaO · P} 2 O 5 to 2CaO · phases SiO ₂ is solid-solved, 4CaO · P ₂ O _5, and at least one FeO The CO ₂ absorption promoting method according to claim 1. 3. The CO ₂ absorption promoting method according to claim 1 or 2, wherein a mixture of two or more kinds of steel slag having different component compositions is used. 4. The CO ₂ absorption promoting method according to claim 1, wherein the municipal wastewater and / or the inorganic ammonium salt is used as a nutrient salt together with the steel slag. 5. Adjusting the grain size and specific gravity of the steel slag,
The sedimentation velocity in seawater is 0.01 m / sec or less.
The CO ₂ absorption promoting method according to any one of 4 above. 6. The steel slag used is at least one selected from blast furnace slag, hot metal pretreatment slag, converter slag, electric furnace slag, smelting reduction furnace slag, secondary refining slag, and stainless slag. The method for promoting CO ₂ absorption according to any one of 1 to 5. 7. A nutrient salt for propagating phytoplankton is extracted as an aqueous solution from steel slag, and the aqueous solution is sprayed as a nutrient for phytoplankton to the applicable ocean, and the phytoplankton existing in the relevant marine area is propagated to produce CO ₂ A method for promoting CO ₂ absorption in the ocean, which comprises promoting absorption of CO ₂ .