JP6912752B2 - Slag molded body - Google Patents

Description

The present invention relates to a slag molded product in which steelmaking slag is used as a raw material and used in an aquatic environment.

In recent years, the decrease in fishery resources has become a problem in the sea area near the coastal area of the ocean, and the decrease in iron content is considered to be one of the causes.

In addition, there is a problem of mud sediment in the sea area near the coast, and this mud sediment is also one of the causes of the decrease in marine resources, so it is suitable for the habitat of marine organisms. It is required to be appropriately modified to.

As a method for improving the mudification of the sediment, there is a method of modifying the sediment into a highly permeable sand.

As a measure against sediment mud formation by reforming to a highly permeable sandy state, the development of environmental repair materials using steelmaking slag is being promoted mainly by steel makers, but most of these environmental repair materials are Since it is a hydrated solidified product with a relatively large particle size, it has high strength and does not easily change to sand in an aquatic environment.

Therefore, it is conceivable to directly put the environmental repair material, which is a hydrated solidified body, into the sea area as sand-like slag whose particle size is adjusted by crushing, etc. Dust is generated during the construction process and the working environment tends to deteriorate, resulting in poor handleability.

In addition, after construction, the hardness increases due to the compressive action of the expansion reaction that accompanies hydration and solidification, so it is possible that the sediment will change to a sediment that is difficult for living organisms to inhabit.

As a method for handling steelmaking slag having a small particle size, for example, as in Patent Document 1, a method is known in which a coconut fiber bag is packed and put into a sea area for construction.

Japanese Patent No. 3829140

However, in the method of Patent Document 1 described above, since it takes time to decompose the coconut fiber after construction, it takes time to expose the sandy slag surface layer in water, which is effective for the sediment in the aquatic environment. It may not be possible to improve.

The present invention has been made in view of these points, and an object of the present invention is to provide a slag molded product which is easy to handle and can effectively improve the water environment and its bottom sediment.

Slag molded body described in claim 1 is a slag forming material to be used in water environment, Ri grains der of the steelmaking slag and pectin-containing materials are mixed, the pectin-containing materials are citrus skin Is what.

The slag molded product according to claim 2 is the slag molded product according to claim 1, which contains at least one of lignin sulfonic acid and a metal salt thereof.

The slag molded product according to claim 3 is the slag molded product according to claim 1 or 2, wherein the granules have a particle size or a total length of 10 mm or more and 40 mm or less.

Slag molded body described in請Motomeko 4, in claims 1 to 3 slag formed body of any one described, citrus skin has been ground to 5mm or less, the content is 2 mass% or more Is what.

According to the present invention, the granules are mainly composed of steelmaking slag and a pectin-containing substance , and since the pectin-containing substance is a citrus exodermis , it is easy to handle and can effectively improve the water environment and its sediment. ..

Hereinafter, the configuration of one embodiment of the present invention will be described in detail.

The slag molded body is used as an environmental repair material or the like in a water environment such as seawater such as a coastal area of the ocean. Then, when it is put into the water environment and sunk on the seabed for construction, it exerts an environmental repairing action or a fertilizing action.

In this slag molded body, steelmaking slag as a main raw material and citrus hull which is a pectin-containing mixture as a mixture are mixed.

Further, it is preferable that the slag molded product is mixed with lignin sulfonic acid as a binder in addition to the raw materials such as the main raw material and the mixture.

The slag molded body is formed into granules from the viewpoint of handleability in transportation, construction, etc., and from the viewpoint of easily forming a gap between the slag molded bodies at the time of construction.

If the size of the granules, that is, the particle size or the total length is larger than 40 mm, the slag molded body may have a reduced compression buffering action during expansion after construction and may be easily cured, and the slag molded body may be easily cured after construction. It may take some time for the slag to collapse into sand. Further, if the size of the granules is smaller than 10 mm, dust may be easily generated and the granulation efficiency may be lowered. Therefore, the particle size or the total length (diameter) of the slag molded product is preferably 10 mm or more and 40 mm or less.

Steelmaking slag, which is the main raw material, is produced in large quantities as a by-product in the steelmaking process in the production of steel products, and is used in the form of granules or powder.

This steelmaking slag contains a large amount of iron (Fe), and also contains other elements such as calcium (Ca), magnesium (Mg), silicon (Si), and phosphorus (P). Then, when the slag compact collapses in the water environment, the elements contained in the steelmaking slag are eluted and act as an active ingredient in environmental repair or fertilization.

Further, since the particle size of the slag molded body after collapse in the water environment is considered to be affected by the particle size of the steelmaking slag before being formed into granules, the state after collapse in the water environment is taken into consideration in steelmaking. The particle size of the slag may be adjusted as appropriate.

The citrus hull, which is a mixture, is, for example, a hull of mandarin oranges, lemons, etc. generated as a by-product of the juice manufacturing process (juice squeezing process).

Since such a citrus hull contains a large amount of pectin that is soluble in alkali, decomposition is promoted by the alkali eluted from the steelmaking slag in the slag molded product. As a result, gaps are also formed in the granules, and the slag molded product is liable to collapse without solidifying after construction, and the slag molded product has an effect of improving the disintegration property in the water environment.

In addition, the gaps in the granules act to loosen the compression when an expansion reaction occurs, and suppress the increase in hardness due to the expansion reaction.

In addition, since the organic acid contained in the citrus hull exerts an iron chelating action, the amount of iron eluted can be improved, the amount of iron eluted in the water environment of the slag molded product is improved, and the environmental repairing action and fertilizing action are exerted. It is also effective from the viewpoint of.

In a wet state, the citrus husk is prone to putrefaction and is not suitable for long-term storage, and can be stored frozen, but energy (electric power) for freezing is required and the storage cost increases. Furthermore, when producing a slag molded product, if granulation (briquetting) is not performed with an appropriate amount of water, the strength and yield in the granulation process may decrease, but the citrus hull is in a wet state. If this is the case, the water concentration becomes unstable, and it may be difficult to control the water content during granulation. Therefore, the citrus husk is preferably used in a dry state when mixed with the main raw material or the like.

Further, the citrus husks are preferably mixed in a state of being crushed to 5 mm or less so that they can be easily mixed uniformly.

Further, if the content of the citrus husk is less than 2% by mass, the effect of improving the disintegration property in the aquatic environment may not be ensured, while the content of the citrus husk when mixed is 20% by mass. If it exceeds%, the strength of the slag molded product may be lowered more than necessary. Therefore, the content of the citrus exodermis is preferably 2% by mass or more, more preferably 2% by mass or more and 20% by mass or less.

As pretreatment drying for drying the citrus husk, if the temperature is less than 60 ° C, it takes time to dry and it is inefficient, and if it exceeds 80 ° C, it may be charred and carbonized. be. Therefore, the pretreatment drying temperature of the citrus exodermis is preferably 60 ° C. or higher and 80 ° C. or lower.

As the mixture, in addition to the citrus hulls containing pectin, other mixtures may be appropriately mixed for the purpose of increasing the strength, increasing the amount of iron elution, and the like.

Further, the mixture is not limited to the citrus hull, and may be a pectin-containing substance containing pectin. Examples of the pectin-containing substance other than the citrus hull include pulp obtained in the citrus juice squeezing step, the inner skin of the fruit, and the fruit itself. Pulp is an unnecessary solid content that is further sedimented and separated from the juice. When the fruit itself is used, it is preferable to use a fallen fruit or the like that cannot be shipped as food because it falls off due to strong wind or the like before ripening.

Furthermore, if the content of pectin in the granules (slag molded product) is less than 0.6% by mass, the pectin-containing substance may not sufficiently promote the decomposition by alkali, and therefore the pectin in the granules. The content of is preferably 0.6% by mass or more.

Since the dried citrus hull contains about 30% by mass of pectin, when the citrus hull is contained in an amount of 2% by mass or more as a mixture, the content of pectin in the granules is 0.6% by mass or more. It becomes.

The binder, lignin sulfonic acid, and a metal salt thereof have an effect of increasing the amount of iron elution due to the iron chelating action, and improve the yield when granulating the slag molded product into granules.

When lignin sulfonic acid or a metal salt thereof is mixed as a binder together with the main raw material and the mixture, if the amount of the binder added is less than 5% by mass, both the chelating action and the strength may decrease. Therefore, when a binder is added, its content is preferably 5% by mass or more.

When producing the above-mentioned slag molded body, first, steelmaking slag such as converter slag is crushed into granules, and the slag is adjusted to a predetermined particle size, for example, 5 mm or less by sieving. The steelmaking slag may be made into a powder by further crushing the slag into granules to a predetermined size, for example, 200 μm or less.

Further, the citrus hull, which is a mixture, is crushed to 5 mm or less in a wet state and dried to a predetermined temperature as a pretreatment. If necessary, it may be further pulverized to a predetermined size, for example, 1 mm or less after drying.

Moisture is appropriately added to these main raw materials (steelmaking slag) and the mixture (citrus hulls), and the mixture is mixed with a kneader. When mixing, a binder may be added together with the main raw material and the mixture, if necessary.

What is mixed by a kneader is granulated and molded into a predetermined particle size, for example, 10 mm or more and 40 mm or less by a briquette machine or the like to obtain granules.

Then, the granulated granules are dried at a predetermined temperature, for example, 105 ° C. to obtain steelmaking slag.

Next, the action and effect of the above embodiment will be described.

Since the slag molded product is a granular material, when it is put into a water environment such as a coastal area of the ocean, it is sunk with a gap between the slag molded products.

The slag molded body that has been sunk gradually collapses due to contact with water and the decomposition action of the citrus hull by the alkali eluted from the steelmaking slag. As a result, the steelmaking slag that collapses and turns into sand changes to sandy sediment.

In addition, as the steelmaking slag decomposes, active components such as iron elute from the steelmaking slag, but since the organic acid of the citrus hull exerts an iron chelating action, water is more effective than simply elution of iron from the steelmaking slag. Iron is supplied to the environment, and it has an environmental repairing action and a fertilizing action.

According to the slag molded product, since it is a granular material, it is difficult to generate dust before construction in a water environment, that is, during transportation or construction, and the handleability is good.

In addition, after construction in the aquatic environment, iron can be effectively supplied to the aquatic environment by the action of improving the disintegration property by decomposing the citrus hull and the action of improving the iron elution amount by the organic acid contained in the citrus hull. At the same time, the disintegration property can be improved. Therefore, it is effective from both the viewpoints of environmental repair and fertilization, and the water environment can be effectively improved, and the bottom sediment of the water environment can be effectively improved.

Further, by containing at least one of lignin sulfonic acid and a metal salt thereof as a binder, the amount of iron eluted can be improved by the iron chelating action, and the yield can be improved at the time of granulation when producing a slag molded product.

By setting the particle size or overall length of the granules that make up the steelmaking slag to 10 mm or more and 40 mm or less, it is possible to secure a compression buffering action during expansion after construction in an aquatic environment, and prevent the steelmaking slag from hardening more than necessary. can.

By mixing citrus husks having a thickness of 5 mm or less, it is easy to mix them uniformly, and it is easy to secure a disintegration improving action and an iron elution amount improving action.

Further, by setting the content of the citrus exodermis to 2% by mass or more, it is easy to secure the action of improving the disintegration property and the action of improving the amount of iron elution.

Hereinafter, this example and a comparative example will be described.

Steelmaking slag was produced under various conditions, and an dissolution test for evaluating iron elution and an actual sea immersion test for evaluating disintegration were performed.

When producing steelmaking slag, granular steelmaking slag or powdery steelmaking slag was used as the main raw material.

Granular steelmaking slag is obtained by crushing converter slag and then sieving to adjust the size to 5 mm or less, and powdery steelmaking slag is obtained by further crushing granular steelmaking slag to 200 μm or less.

As the mixture, in addition to the citrus hulls of mandarin orange hull and lemon hull, waste wood chips, humus soil, waste bamboo chips and red soil were used as comparative examples.

The citrus husk was crushed to 5 mm or less in a wet state, dried at 80 ° C. for 4 hours, and then crushed to 1 mm or less. In addition, all the mixtures of Comparative Examples were pulverized to 1 mm or less as they were.

When the binder was added, Sun Extract M100 (Sun Extract is a registered trademark), which is a lignin sulfonic acid, was used.

Then, a binder and water were appropriately added together with the main raw material and the mixture, and the mixture was mixed in a kneader.

After mixing with a kneader, granulation was performed with a briquette machine to a particle size of about 30 mm, and the granulated product was dried at 105 ° C. for 24 hours to prepare various samples of a slag molded product.

In the dissolution test, 100 g of the slag molded product and 100 ml of artificial seawater were placed in a 2 L beaker and stirred continuously for one week with a propeller having a rotation speed of 100 rpm.

After stirring, the iron concentration in the artificial seawater was measured by acid decomposition-inductively coupled plasma mass spectrometry to obtain the Fe elution amount (μg / L).

In the actual sea area immersion test, no elution of iron was observed in the elution test. 7 and No. This was performed using a sample other than 9.

In this actual sea area immersion test, a plastic container was filled with about 30 kg of a slag molded product and immersed in seawater along the coast of the Seto Inland Sea for one year.

Further, a sample after immersion was collected, dried at 105 ° C. for 24 hours, and then the dried sample was sieved to 20 mm or less.

Then, when the weight under the sieve by sieving was 20 kg or more, the disintegration property was evaluated as good (◯), and when the weight under the sieve was less than 20 kg, the disintegration property was evaluated as poor (x).

Table 1 shows the detailed production conditions of this example and the comparative example, the results of the immersion test in the actual sea area, and the results of the dissolution test.

As shown in Table 1, No. 1 of this embodiment. 1 to No. In all of No. 6, iron elution was observed and the disintegration property was good.

On the other hand, No. In No. 7, no elution of iron was observed. It is considered that this is because no iron chelate is produced because neither the mixture nor the binder is added.

No. which is a comparative example. In No. 8, although iron elution was observed, the disintegration property was poor. It is considered that this was hardly decomposed because the raw material was only steelmaking slag without mixing the mixture.

No. which is a comparative example. In No. 9, no elution of iron was observed. It is considered that this is because the iron chelate is not produced because the waste wood chips are mixed as a mixture and no binder is added.

No. which is a comparative example. 10 and No. In No. 11, although iron elution was observed, the disintegration property was poor. It is considered that this is because the waste wood chips used as the mixture are not easily decomposed.

No. which is a comparative example. In No. 12, although elution of iron was observed, the disintegration property was poor. It is considered that this is because the humus soil used as the mixture is not easily decomposed.

No. which is a comparative example. In No. 13, although iron elution was observed, the disintegration property was poor. It is considered that this is because the waste bamboo chips used as the mixture are not easily decomposed.

No. which is a comparative example. In No. 14, although iron elution was observed, the disintegration property was poor. It is considered that this is because the red clay used as the mixture is hardly decomposed.

Claims (4)

A slag molded body used in an aquatic environment
Granules der the steel slag and the pectin-containing material is mixed is,
The pectin-containing product is a slag molded product characterized by being a citrus exodermis. The slag molded product according to claim 1, wherein the slag molded product contains at least one of lignin sulfonic acid and a metal salt thereof. The slag molded product according to claim 1 or 2, wherein the granules have a particle size or a total length of 10 mm or more and 40 mm or less . The slag molded product according to any one of claims 1 to 3, wherein the citrus hull is crushed to 5 mm or less and the content thereof is 2% by mass or more.