JP4522179B2 - Method of treating rainwater or snowmelt water with steel slag - Google Patents

Description

  The present invention relates to a method for treating rainwater or snowmelt water. More specifically, sulfur oxides and nitrogen oxides generated in combustion gas by combustion of fossil fuels cause chemical changes in the atmosphere to become sulfuric acid, nitric acid and the like. In regard to a method of treating so-called “acid rain” or “acid mist” rainwater or “acid snow” snowmelt water, which has a pH of 5.6 or less when they are taken into rain, fog, or snow. The present invention relates to a method for reusing steel slag generated in a refining process.

(1) Technology for measures against acid rain, acid snow, etc. In recent years, various environmental pollutions have progressed with the development of industry. Among them, sulfur oxides and nitrogen oxides generated in the combustion gas due to the combustion of fossil fuels. , Causing chemical changes in the atmosphere to become sulfuric acid, nitric acid, etc., and when they are taken into rain or mist, the pH becomes 5.6 or less, so-called "acid rain" or "acid mist" or "acid snow" Environmental pollution and environmental destruction caused by the environment are getting worse year by year.

  Fortunately, compared to Europe and the United States, where there are many rock grounds, Japan's ground is formed from soil containing alkaline components and volcanic ash soil, which acts in the direction of neutralization when it absorbs acid rain. Although it is not as severe as in Europe and the United States, based on various surveys, cedar withering and pine withering have begun to be observed in various parts of the country. The damage is gradually beginning to become evident, such as a report of a drop in pH.

  In this way, acid rain and acid mist cause damage to forests and crops directly or indirectly through soil changes, and cause acidification of lakes and rivers. In severe cases, fish are killed. It has a great influence on the ecosystem.

  In winter, the amount of sulfuric acid and nitric acid in the atmosphere is large because fossil fuels are used. In addition, snow has a longer time to float in space than rain. Is also said to be expensive.

  These acidic substances are accumulated in the snow during the snowfall period, but when the snow melts at the beginning of spring, the acidic substances melt into the melted water all at once. Since it flows into rivers and lakes in large quantities without receiving much buffer, the pH is lowered at once in a clean river with a low degree of pollution, and a phenomenon of acid shock that makes fry of river fish suddenly unable to live has been reported. .

  Furthermore, the damage caused by the melted water of acid snow is not limited to the ecosystem, for example, in urban areas with pavements, it does not receive soil buffering, and the pH of groundwater drops instantaneously, resulting in a structure. Inducing and accelerating corrosion of objects and underground pipes, in snowfall areas, iron oxide (red rust) generated by corrosion during snow melting has become prominent.

  Conventionally, when soil or water quality such as fields, forests and lakes is acidified by acid rain or acid mist as described above, the distribution of alkaline components such as lime powder has been widely used to neutralize it. To be done.

  Furthermore, as a technique for more efficiently improving these acidified reservoirs and soils, for example, the method of Patent Document 1 is disclosed.

The method described in Patent Document 1 relates not only to neutralization but also to a calcined bioceramic containing soft porous ancient marine humus containing minerals present in the seabed and Si ₆ O ₁₈ type polymer silicon. Mineral content can also be supplied.

  In addition, the damage caused by melted water of acid snow in early spring is not so effective because the melting time is irregular depending on the climate of the year and occurs temporarily for a limited period. No specific countermeasures are taken.

(2) Technology for recycling steel slag On the other hand, steel slag, represented by blast furnace slag and steelmaking slag, is a by-product generated during steel production at steelworks, and its reuse is extremely important for the steel industry. Many attempts have been made for a long time to recycle by-products.

  As a result, blast furnace slag has an overwhelming proportion of its use in cement raw materials because its chemical composition is close to that of Portland cement and has excellent hydraulic properties. Besides, the reuse rate is close to 100% for civil engineering and building materials such as roadbed materials and concrete aggregates.

  On the other hand, in the steelmaking slag, the quick lime used as an auxiliary material in the refining process in the converter or the like is not completely melted and hatched in all the CaO as the main component, and finally a part of it is not yet formed In many cases, the reaction remains in a so-called “free CaO” state. When this free CaO reacts with water in the atmosphere and hydrates, the volume expands approximately twice and the steelmaking slag itself collapses. Therefore, it is difficult to use for long-term stable applications such as structures, aggregates for roadbeds, and stones, and it is one of the obstacles when using it as a material for civil engineering work. As a result, reuse cannot be expanded.

  Therefore, as a treatment method for stabilizing the expansion of slag by reducing the free CaO that is the cause of this expansion phenomenon, it can be exposed to the atmosphere for several months to several years and fully hydrated. An “atmospheric aging” process is generally performed.

  Further, as a technique for performing this stabilization processing in a shorter time, for example, methods of Non-Patent Document 1 and Non-Patent Document 2 are disclosed.

  The method described in Non-Patent Document 1 is a “vapor aging” method in which a hydration treatment reaction is promoted by forcibly reacting with water vapor at atmospheric pressure, and the method described in Non-Patent Document 2 is used. Relates to a “pressure aging” method in which a hydration treatment reaction is promoted by forcibly reacting with water vapor under pressure.

JP-A-6-9280 Abstracts of Lecture Meeting of Japan Iron and Steel Institute, Materials and Processes, Vol.9, No.1, p-244 (1996) Abstracts of Lecture Meeting of the Japan Iron and Steel Institute, Materials and Processes, Vol.8, No.4, p-1102 (1995)

  However, the above prior art has the following problems.

  In other words, in the neutralization technology of acidified fields, forests, etc., and lakes, etc., by the distribution of alkaline components such as lime, which is widely common, it is merely a neutralization reaction of soil and lake water quality, There is a problem that it is impossible to provide various minerals necessary for breeding vegetation such as agricultural crops and fish.

  If the cultivation of crops, etc. is continued in such soil, the various minerals contained in the soil will decrease, leading to the growth of crops and the decline in yields, so regular chemical fertilizers are widely distributed. I came.

  However, lime powder and chemical fertilizers that are neutralizers are usually commercially available products, and the cost of processing is generally high, such as tens of thousands of yen per ton of soil or lake water, In carrying out these treatments, the appearance of a neutralizing agent that is as inexpensive as possible is eagerly desired.

The method described in Patent Document 1 includes a soft porous ancient marine humus containing minerals present in the seabed and a Si ₆ O ₁₈ type polymer silicon, as well as a neutralization reaction, as well as a mineral content supply. Although it is a calcined bioceramic product with higher processing efficiency than before, the cost is much higher considering the availability of these raw materials and the equipment such as the firing furnace for firing the ceramic and the necessary thermal energy. It is unlikely to decline.

  In addition, lime powder, which is a neutralizing agent, is a fine powder and easily spreads in the atmosphere. Care must be taken in handling the lime powder so as not to cause irritation to the skin during use.

  On the other hand, regarding the reuse of steel slag, especially steel slag, steelmaking slag itself collapses due to the expansion phenomenon that occurs when free CaO remaining in it reacts with water in the atmosphere to hydrate. For example, in order to use it as a civil engineering material such as road roadbed material, it is necessary to stabilize the steelmaking slag itself by promoting this hydration reaction. “Atmospheric aging” is performed for months to years to expose and fully hydrate.

  However, because this steelmaking slag is generated at about 120kg per ton of steel, large steelworks require land and equipment to store more than 1 million tons of slag, and enormous costs are required for its maintenance. I need it.

  The method described in Non-Patent Document 1 is a “steam aging” method in which a hydration treatment reaction is promoted by forcibly reacting with water vapor at atmospheric pressure in order to shorten the time for stabilization. However, for this treatment, it is necessary to pile steelmaking slag in a certain partitioned section and, for example, to uniformly blow water vapor into the steelmaking slag from the bottom for several days. More expensive than atmospheric aging treatment.

  Similarly, the method described in Non-Patent Document 2 is also a “pressure aging” method in which a hydration treatment reaction is promoted by forcibly reacting with water vapor under pressure in order to shorten the stabilization time. However, for this treatment, it is necessary to put the steelmaking slag into a special high-pressure vessel and blow the pressurized water vapor. Although the treatment takes less time compared to the steam aging method described above, it is exclusively used in the first place. The amount of slag that can be processed in a high-pressure vessel is about 50 tons at a time, and in addition to a dedicated high-pressure vessel, steam aging treatment is required because it requires considerably large equipment such as a high-pressure boiler and pressure-resistant piping to produce high-pressure steam. Actually, it costs more than that.

The present invention has been made in view of the various circumstances described above, and sulfur oxides and nitrogen oxides generated in combustion gas by combustion of fossil fuels cause chemical changes in the atmosphere to sulfuric acid and nitric acid. The refining of steel mills is related to the so-called “acid rain”, “acid fog” rainwater or “acid snow” snowmelt water treatment method, in which the pH becomes 5.6 or less when they are taken into rain or fog. as means for effectively utilizing the characteristics possessed by the steelmaking slag generated in the process, is passed through the該雨water or meltwater in steelmaking slag, or by such dipping the steelmaking slag該雨water or snowmelt, Ltd. and steel slag, by contacting the rainwater or snow melting water can steelmaking slag fulfill the function of neutralizing agent to produce a lower layer subgrade material from steelmaking slag causes a neutralization reaction rainwater or meltwater Na There is provided a method of processing rainwater or meltwater by steelmaking slag also serves as valence and resource saving.

  In order to solve the above-mentioned various problems, the inventor has examined an effective utilization method of chemical properties of steel slag.

  As a chemical property of steel slag, the main component contains CaO.

  Therefore, if this CaO content contributes to the neutralization reaction of acid rainwater or snowmelt water and neutralizes the acidified rainwater or snowmelt water, it can be used effectively. As a result, the present invention has been newly found.

  In addition, among steel slag, especially in steelmaking slag, compared with blast furnace slag, which is sufficiently reused, a part of quick lime that is not completely melted and hatched during refining remains as free CaO. Since this free CaO reacts with water in the atmosphere after cooling and expands due to hydration, causing collapse of the steelmaking slag itself, materials that require stability such as aggregates for civil engineering work It is very difficult to apply, and costs for promoting its stabilization are required.

However, other words, the steel slag is in its main component serving total CaO content not only free CaO can sufficiently react with yet acid, 2CaO · SiO ₂ or _{3CaO · SiO 2, 2CaO · Fe} 2 O 3 It is a reason why it can be used effectively if it has the function of neutralizing acidified rainwater and snowmelt water.

  The gist of the present invention is as follows.

Processing method rainwater or meltwater by steelmaking slag according to the first invention, the rain or snow melting water, and Turkey to neutralize the reaction treated with steelmaking slag to be reused in the neutralization reaction treatment after undercoating roadbeds It is characterized by .

Processing method rainwater or meltwater by steelmaking slag according to the second invention, Oite the first inventions, the apparent porosity of the steelmaking slag are characterized by a 10% or more, the neutralization reaction The processing efficiency is further increased.
Processing method rainwater or meltwater by steelmaking slag according to the third invention, in the first or second aspect, the manufactured steel slag filler wire mesh shaped container, the container after the filling, It is characterized by being installed in the flow path of rainwater or snowmelt water, or immersed in a reservoir of rainwater or snowmelt water.

According to the present invention, it passed through a rain or snow melting water steelmaking slag or the steelmaking slag by such dipping rainwater or snow melt water, by contacting the steelmaking slag and rain or snow melting water, an acidic for a rain or snow melting water to CaO content which is the main component of the steelmaking slag is alkaline, steelmaking slag fulfill the function of neutralizing agent, by neutralization reaction rainwater or snow melting water, the rainwater or meltwater while neutralization process, it is possible to produce the lower layer subgrade material from the steel steel slag.

As described above, since steelmaking slag is a by-product in the steel industry, it is not necessary to purchase a commercial expensive neutralizing agent by applying it to the neutralizing agent, of rainwater and snow melting water treatment costs reduced not only it is possible, included in the steelmaking slag, iron and silicon content, magnesia content, since the dissolving minerals which said phosphoric acid content in water, processing was carried out rainwater and snow melting water crops It also has the secondary effect of reducing or eliminating the amount of fertilizer applied.

Conventionally, lime powder that has been used widely spreads easily in the atmosphere for fine powder, so as not to cause irritation to such skin during use, but the handling has required noted, steelmaking Slag is a solid material that consists of a stable mineral layer, in which iron ore dissolves and the remaining oxide from which iron has been extracted is solidified, as if it were touched with bare hands like a stone. Is less likely to occur and is easy to handle in terms of work environment.

Furthermore, since the CaO content is the main component contributes to the neutralization reaction, the points of free CaO was remarkable in steelmaking slag reuse by slag expansion problem is caused had been inhibited, acidified Since the free CaO in the steelmaking slag is consumed by the neutralization reaction of rainwater and snowmelt water, the steelmaking slag is simultaneously stabilized and the steelmaking slag can be reused.

  Therefore, conventionally, stabilization processing such as air aging, steam aging, and pressure aging, which has been necessary for reusing steelmaking slag as a construction material such as roadbed material and aggregate, is unnecessary, and the cost may increase. Absent.

In other words, the steelmaking slag capacity of the neutralization reaction is reduced or terminated, then, in addition to the construction work for the raw materials such as roadbed material or aggregate, agricultural fertilizer on land that was characterized by mineral supply such as iron and silicon and, as a natural stone substitute material for the seagrass beds in the rivers and in the sea water, dripping also a new advantage that can take advantage of to further re-use.

  Hereinafter, the method of the present invention will be described in detail.

In the present invention, rainwater or snowmelt water, more specifically, sulfur oxides and nitrogen oxides generated in the combustion gas by the combustion of fossil fuels cause chemical changes in the atmosphere to sulfuric acid, nitric acid, etc. and fog, pH becomes 5.6 or less by being incorporated into the snow, the snow melting water of the so-called "acid rain" and rainwater or "acidic snow" in "acid fog", to neutralization treatment with steelmaking slag.

And CaO is a main component of the steelmaking slag, neutralization reaction of rainwater or snow melting water acidified by dissolving sulfuric component or nitric acid component is shown as follows.

CaO + H ₂ O → Ca (OH) ₂ → Ca ²⁺ + 2OH ⁻
H ₂ SO ₄ → 2H ⁺ + SO ₄ ²⁻
CaO + H ₂ SO ₄ → CaSO ₄ ↓ + H ₂ O
_{CaO + H 2 O → Ca (} OH) 2 → Ca 2+ + 2OH -
^{_{2HNO 3 → 2H + + 2NO 3}} -
CaO + 2HNO ₃ → Ca (NO ₃ ) ₂ ↓ + 2H ₂ O

However, the amount and particle size of the steelmaking slag in the neutralization reaction treatment of the present invention, conditions such as operating temperature is not intended to be limited to the exact neutralization of the rain or snow melting water, rain or snow melting water of interest Depending on the degree of acidity of water, the amount of water or the flow rate, the adverse effect of acidification can be alleviated, preferably the pH deviates from the definition of acid rain or acid snow, more preferably in the range of 5.6 or more, and more preferably pH 7 What is necessary is just to control so that rainwater and snowmelt water can be neutralized appropriately in the range where improvement can be achieved.

The iron steel slag, but blast furnace slag and steel slag, a by-product generated in each refining process during steel production in steel works is typical, among others, some of the quick lime is not completely melted and slag formation during refining steelmaking slag remaining number as the free CaO is cut with a utilization.

  Therefore, the steelmaking slag will be described below as an example.

  In practice, the steelmaking slag is generally manufactured and processed as a by-product through the following steps. In other words, when the desired refining process is completed, the steelmaking slag is separated from the required molten metal (molten steel), transferred to a dedicated container, and then collected and discharged at a specific location within the steelworks premises, sprinkling water or air as it is. It is allowed to cool inside and becomes a rock-like solidified product.

  The solidified steelmaking slag is then roughly crushed by a heavy machine or the like, and the iron content remaining in the slag is recovered. As a result, steelmaking slag mainly composed of oxide components is, for example, an aggregate of slag grains having a maximum particle size distribution of 40 mm or less required for civil engineering materials (JIS A5015 in steel slag for roads). It is further crushed and classified (sieved) to the specified crusher run steel slag CS-40 for the subbase material for the lower layer.

  In this way, since the particle size distribution is relatively uniform, the free CaO content in the slag is then analyzed by chemical analysis (eg, ethylene glycol extraction-atomic absorption photometry). If it measures, the amount of CaO required for the neutralization reaction which steelmaking slag has can also be calculated | required.

  In addition, when the neutralization ability of steelmaking slag is reduced or terminated after an arbitrary period of time, the steelmaking slag is replaced with new steelmaking slag. In addition, it can be further reused as a fertilizer for agriculture on land characterized by the supply of minerals such as iron and silicon, and as a substitute for natural stone for seaweed beds in rivers and seawater.

  As a specific method for neutralizing and reacting rainwater or snowmelt water with this steelmaking slag, for example, a metal mesh-like special container filled with the above steelmaking slag of 40 mm or less with an appropriate space (porosity) Are prepared, and installed in a flow path through which rainwater or snowmelt water flows at an appropriate interval so that the rainwater or snowmelt water passes through the steelmaking slag at a constant flow rate. Further, in a place where a certain amount of water is accumulated, such as a reservoir, a dedicated container filled with these steelmaking slags may be immersed in the water.

  At this time, it is estimated that the neutralization reaction shown earlier is a rate-limiting step in which free CaO in steelmaking slag dissolves in water and hydrates, so that steelmaking slag and rainwater or snowmelt In order to increase the contact area of water, it is desirable that a relatively large steel slag is pulverized and sized in advance.

  The slag particle size to be sized is not fine in theory, but it is difficult to artificially control the amount of rainwater and snowmelt water, and in fact, it is a heavy rainstorm and a lot of snowmelt The lower limit is preferably about 1.0 mm because there is a concern that even if the degree of slag filling is too dense, it may cause a flood-like state. Considering further reuse for new applications, the upper limit is preferably about 10 mm.

  In addition, if the steelmaking slag grains are agglomerated into blocks that require an arbitrary filling rate and shape using, for example, Portland cement or blast furnace cement as a binder, a wire mesh like as described above A dedicated container is also unnecessary, and it is possible to more efficiently install steelmaking slag for the neutralization reaction, remove the steelmaking slag after the neutralization reaction, and replace it with new steelmaking slag.

  Furthermore, for places where acid rain falls directly, such as in forests and fields, steel slag is laid directly on the soil so as to have an arbitrary thickness. It is also possible to take a form in which precipitation passes through the strata.

From the above, the first invention is a method of treating rainwater or snow melting water was defined as the neutralizing reaction at steelmaking slag rainwater or snow melting water.

Then, the neutralization reaction of rainwater or meltwater by the steelmaking slag, in the same amount of slag or slag grain size was investigated a method for further promoted.

  Here, similarly, steel slag will be described as an example.

  Previously, it is estimated that this neutralization reaction is the rate-limiting step in which free CaO in steelmaking slag dissolves in water and hydrates, increasing the contact area between steelmaking slag and rainwater or snowmelt water. It is said that it is preferable to pulverize and size a large steelmaking slag in advance, but if the particle size of the slag is made fine and the slag filling degree in the container is too dense, it will be per unit time. Since the amount of water that can be passed decreases, for example, when a large amount of snow melt flows in a short time, such as the snowmelt in early spring, the balance between the amount of water that can pass and the actual amount of water is lost, and There is also a concern of causing such a situation.

  Therefore, the inventor focused attention on the physical properties of the steelmaking slag in order to further increase the surface area of the steelmaking slag with the same slag particle size or slag amount.

  That is, if each grain of steelmaking slag is not as dense as natural stone and is in a porous state like pumice, rainwater or snowmelt water penetrates into the steelmaking slag more easily, and the reaction interface area We thought that we could secure.

Here, the density of the steelmaking slag generated in a general refining process is about 2 g / cm ³ , and the apparent porosity existing in the slag is about 5 to 10%. However, under certain operating conditions in the refining process, steelmaking slag in a so-called “forming” state, in which a large amount of fine gas is present in the molten steelmaking slag, may be generated. When is rapidly cooled, as a result of the gas remaining inside the steelmaking slag, a very porous pumice-like one can be obtained.

  When the apparent porosity of these porous steelmaking slags is measured, some of them are found to be approximately 10% or more, and in some cases about 50%. If these steelmaking slags are used, they are necessary for the neutralization reaction treatment. It has been found that it is possible to increase the reaction interfacial area easily. Here, as a method for measuring the apparent porosity of this steelmaking slag, for example, “Measurement method of apparent porosity / water absorption / specific gravity of JIS R2205 refractory brick” may be used.

From the above, the second invention, in the first invention, in order to increase the efficiency of the neutralization reaction treatment, the apparent porosity of the steelmaking slag was defined as 10% or more.

Example 1
An experiment using the method according to the present invention was performed by using a part of a gutter line (U-shaped groove) for draining rainwater on the side of the road in the steelworks. The steelmaking slag used for the neutralization reaction process is defined from the representative of steelmaking slag converter slag, without almost atmospheric aging for stabilization, in "JIS A5015 for roads Slag" The maximum particle size of 40 mm or less meeting the standard of “Crusheran Iron and Steel Slag CS-40 for Subbase Material for Lower Layers” was prepared by adjusting the particle size by crushing and classification. Table 1 shows an example of analysis results of chemical components of this steelmaking slag.

  A plurality of slag grains having an arbitrary particle size were collected from the steelmaking slag, and the apparent porosity was measured by “Measurement method of apparent porosity / water absorption / specific gravity of JIS R2205 refractory brick”. The average density was about 7%, which was confirmed to be a general dense state.

  In addition, when the water immersion expansion ratio of this steelmaking slag was measured based on the “method of water immersion expansion test of steel slag” defined in Annex 2 of “JIS A5015 road steel slag”, 2.5. % Was confirmed to be a large number.

As shown in FIG. 1, a steelmaking slag 2 prepared as described above is placed in a wire mesh cage 1 having a width of 0.3 m, a height of 0.2 m, and a length of 0.3 m. those filled while creating an appropriate space to be approximately m ³ to create five, as in the interval of the cage with each other is 0.3 m, as flowing water direction 3 inside the above U-shaped groove I set it.

  In this state, rainwater accompanying the rain gathers in the U-shaped groove, and when the rainwater begins to pass through the cage filled with steelmaking slag, the upstream and downstream of the group of cages filled with steelmaking slag for a certain period of time. A certain amount of rainwater was collected every time and the pH of each was measured. In addition, the average hourly rainfall during the rainfall period in which the experiment was conducted this time was 5 mm.

  The pH value of the rainwater thus measured is a value of 4.8 to 5.2 on the downstream side of the cage after the neutralization reaction treatment, whereas the pH value of the upstream side of the cage is 4.3 to 4.7. It was confirmed that the acidification was improved. The pH was measured using a commercially available portable pH meter.

  Similarly, when the trace component analysis of the collected water upstream and downstream of the car group was performed, minerals such as iron, silicon, and phosphoric acid, which were hardly detected on the upstream side, were detected slightly on the downstream side.

  The cages containing the steelmaking slag are left undisturbed for 6 months in a natural rain condition and then taken out, and the steelmaking slag in the “steel slag for steel road slag” defined in Annex 2 of “JIS A5015 road steel slag” Based on the water immersion expansion test method for slag, the water expansion ratio was measured, and the numerical value was improved to 0.4%. This steelmaking slag is the “crusheran steel slag CS for roadbed materials for lower layers”. It was found that it can be used sufficiently for -40 ".

(Example 2)
When an experiment using the method according to the present invention shown in Example 1 was performed, the same steelmaking slag as that previously shown in Table 1 was further classified and sized so that the maximum particle size would be 10 mm. I prepared what I did.

Also the same manner as in Example 1, in a wire mesh basket width 0.3 m × height 0.2 m × length 0.3 m, the steel slag about 20 kg, with a bulk density 1.2 ton / ^{m 3} In order to obtain a suitable level, five pieces were filled while creating a suitable space, and set inside the U-shaped groove on the opposite side of the road so that the distance between the cages was 0.3 m.

  In this state, rainwater accompanying the rain gathers in the U-shaped groove, and when the rainwater begins to pass through the cage filled with steelmaking slag, the upstream and downstream of the group of cages filled with steelmaking slag for a certain period of time. A certain amount of rainwater was collected every time, and each pH was measured using the same commercially available portable pH meter as in Example 1. The average hourly rainfall during the rainy period in which the experiment was conducted was 5 mm.

  When the amount of rainfall increased and the amount of water in the U-shaped groove increased, water was occasionally collected on the upstream side of the car, but the measured rainwater pH value was 4.3 on the upstream side of the car. With respect to the value of ˜4.7, the downstream side of the cage after the neutralization reaction treatment has a value of 5.2 to 5.8, and it was confirmed that the acidification was further improved compared to Example 1. .

  In addition, as in Example 1, the mineral content of rainwater on the downstream side of the cage increased with a slight amount.

(Example 3)
From the experimental results of applying the method according to the present invention shown in Example 2, when the steelmaking slag grain to be used is made finer, when the amount of water in the U-shaped groove increases with the increase in rainfall, the upstream side of the car In this case, an experiment using porous steelmaking slag was conducted.

That is, steelmaking slag used for the neutralization reaction process, from among the representative of steelmaking slag converter slag was quenched ones "forming" shape with fine gas is present in large amounts in slag in a molten state, Visually apparent porous pumice-like steelmaking / converter slag is selected and classified and adjusted so that the maximum particle size becomes 10 mm as in Example 2, without air aging treatment for stabilization. Prepared a grain. Table 2 shows an example of the analysis results of the chemical components of this steelmaking slag.

  A plurality of slag grains having an arbitrary particle diameter were sampled from the steelmaking slag, and the apparent porosity was measured in the same manner as “Measurement method of apparent porosity / water absorption / specific gravity of JIS R2205 refractory brick”. % Was obtained, and it was confirmed that the porous state was about 25% on average.

  In addition, when the water immersion expansion ratio of this steelmaking slag was measured based on the “Method of water immersion expansion test of steel slag” defined in Annex 2 of “JIS A5015 road steel slag”, 2.0. %.

About 20 kg of this steelmaking slag is placed in a bulk density of 1 in a cage made of wire mesh of the same width 0.3 m × height 0.2 m × length 0.3 m as used in Example 1 and Example 2. Five items were prepared while creating an appropriate space so as to be about 0.0 ton / m ³ , and set inside the U-shaped groove so that the distance between the cages was 0.3 m.

  In this state, rainwater accompanying the rain gathers in the U-shaped groove, and when the rainwater begins to pass through the cage filled with steelmaking slag, the upstream and downstream of the group of cages filled with steelmaking slag for a certain period of time. A fixed amount of rainwater was collected every time, and the pH of each was measured with the same commercially available portable pH meter as in Examples 1 and 2. In addition, the average hourly rainfall during the rainfall period in which the experiment was conducted this time was 6 mm.

  The pH value of the rainwater thus measured is a value of 5.3 to 5.9 on the downstream side of the cage after the neutralization reaction treatment, whereas the pH value of the upstream side of the cage is 4.4 to 4.9. The improvement of acidification to the same extent as in Example 2 has been made. Furthermore, even if the amount of rainfall increases and the amount of water in the U-shaped groove increases, there is no state in which rainwater accumulates on the upstream side of the cage. Not observed.

  In addition, as in Examples 1 and 2, the mineral content of the rainwater on the downstream side of the car increased in a trace amount.

  The cages containing the steelmaking slag are left undisturbed for 6 months in a natural rain condition and then taken out, and the steelmaking slag in the “steel slag for steel road slag” defined in Annex 2 of “JIS A5015 road steel slag” Based on the “water immersion expansion test method for slag”, the water expansion ratio was measured, and the numerical value was improved to 0.5%. This steelmaking slag is also used in the “crusheran steel slag CS for roadbed materials for lower layers”. It was found to be usable for “-20”.

Was charged with steelmaking slag is a diagram showing a wire mesh-like special container.

Explanation of symbols

1 wire mesh-like basket container 2 made of steel slag 3 flowing water direction

Claims (3)

Rainwater or snow melting water treatment method of rainwater or meltwater by steelmaking slag, wherein the Neutralization reaction treatment to Turkey with steelmaking slag to be reused in the neutralization reaction treatment after undercoating roadbeds. Processing method rainwater or meltwater by steelmaking slag according to claim 1, wherein the apparent porosity of the manufactured steel slag is 10% or more. The manufactured steel slag filler wire mesh shaped container, according to claim 1, the container after the filling, is placed in the flow path of rainwater or snow melting water, or, characterized in that immersion in reservoirs rainwater or meltwater or treatment method of rainwater or meltwater by steelmaking slag described.

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