JP5664087B2 - Method for predicting OH-load of seawater by slag injection and method for preparing or selecting slag for seawater input - Google Patents

Description

A method for predicting the amount of OH ^- load that slag gives to seawater in the sea surface to the visible water depth region when slag is introduced into the sea as marine civil engineering materials, etc., and using this prediction method, the sea surface to the visible water depth region The present invention relates to a method for preparing or selecting a slag for seawater input that does not cause white turbidity in seawater.

  In the metal refining and smelting processes, various types of slag are generated in order to obtain high-quality, high-quality metals, and even in steelworks, blast furnace slag, hot metal pretreatment slag, converter decarburization slag, ladle slag Various slags having different compositions are generated. These slags are not only roadbed materials, soil improvement materials, ground improvement materials, cement and concrete aggregates, stones, but also submarine materials in the ocean, lining materials, backfill materials, surfacing materials, sand compaction, SCP sand It is used as marine civil engineering materials such as mats and shallow-place construction materials.

Among these slags, many steelmaking slags (for example, hot metal pretreatment slag, converter decarburization slag, ladle slag, etc.) contain a relatively large amount of free CaO. When seawater is constructed (introduced) into the sea area, free CaO in the slag is eluted into the seawater, and the pH of the seawater rises, resulting in a clouding phenomenon of seawater. This clouding phenomenon is considered to occur by the following mechanism. That is, free CaO is eluted from the slag into the seawater to produce Ca (OH) ₂ , thereby increasing the pH of the seawater. Due to this increase in pH, Mg ²⁺ dissolved in seawater is precipitated as Mg (OH) _2, and the white turbidity of seawater occurs due to this precipitate.

Although Mg (OH) ₂ itself, which causes white turbidity, is harmless, the white turbidity phenomenon during construction may be an obstacle to advancing harbor construction due to problems in appearance. Also, white turbidity occurs, pH rise of sea water due to the free CaO (OH ^- loading of increase) suggesting must be noted on the environment.
In the recent steelmaking process, efficient division of each step of de-Si treatment, de-S treatment, de-P treatment and de-C treatment, optimization of the order has progressed, and a wide variety of steelmaking slag has occurred, Its shape and structure are diverse, and the dissolution behavior of free CaO in slag is also complicated. In constructing steelmaking slag in the sea area, a method of selecting a slag that does not generate a white turbidity phenomenon from such various steelmaking slags or a method of processing into a slag that does not generate a white turbidity phenomenon has been proposed.

For example, Patent Document 1 discloses a steelmaking slag having a free CaO content of 0 to 10.0 mass% and a sulfur content of 0 to 1.0 mass%, and immersed in seawater having a mass ratio of 2 times for 3 hours. A steelmaking slag for harbor construction in which the pH of seawater at the time when it has passed is 10.5 or less has been proposed. In Patent Document 1, if the pH of seawater is 10.5 or less when it is immersed in seawater having a mass ratio twice that of steelmaking slag for 3 hours, the amount of Ca ²⁺ elution from the steelmaking slag is small, It is said that it can prevent cloudiness when constructed in the sea area. In Patent Document 1, free CaO is 0 to 10.0% by mass, sulfur content is 0 to 1.0% by mass, and the ratio of particles having a particle size of less than 10 mm is 25% by mass or less. It is said that cloudiness is suppressed.

Further, in Patent Document 2, when steelmaking slag with a large amount of fine particles of 0.075 mm or less is immersed in seawater, a large amount of Ca ²⁺ is eluted from the fine particles and a white turbidity phenomenon occurs. A granulated product formed using powdered steel slag containing at least mass%, blast furnace slag fine powder, and water has been proposed. Patent Document 2 states that even steel-making slag with a large amount of fine particles is granulated and coarsened, whereby elution of Ca ²⁺ is suppressed and white turbidity can be prevented.

On the other hand, Patent Document 3 describes Patent Documents 1 and 2 as follows. First, regarding Patent Document 1, it is said that white turbidity can be prevented if the pH of seawater is 10.5 or lower when slag is immersed. It is said that it is insufficient as an evaluation method for preventing white turbidity. Moreover, although patent document 2 can prevent white turbidity, it is said that a granulation process is newly required and the processing cost of slag is increased significantly. For such a problem, Patent Method 3 proposes the following seawater pH increase prediction method. In this method, the amount of Ca ²⁺ eluted when slag is immersed in pure water 1000 times or more of the slag mass is measured, and the relationship between the amount of Ca ²⁺ eluted and the specific surface area of the slag is determined in advance. Based on the particle size distribution of the slag, the amount of Ca ²⁺ eluted from the slag into the sea water at a predetermined depth when the slag is introduced into the sea water is determined, and the amount of Mg ²⁺ present in the sea water is determined from the amount of Ca ²⁺ eluted. It takes into account the buffering effect and predicts the pH of seawater.

JP 2003-26456 A JP 2005-314155 A JP 2009-204272 A

However, the above prior art has the following problems.
As described in Patent Document 3, in Patent Document 1, it is said that white turbidity can be prevented if the pH of seawater is 10.5 or less when slag is immersed, but Mg (OH) which is the main cause of white turbidity. ₂ can occur in the range of pH ≧ 9.5 to 9.8, and since white turbidity is actually generated in seawater exceeding pH 10, Patent Document 1 is considered to be insufficient as an evaluation method for white turbidity prevention. It is done.
Similarly, as described in Patent Document 3, although Patent Document 2 can prevent white turbidity, a new granulation process is required, which causes a problem of greatly increasing the cost of processing slag.

On the other hand, although it is the patent document 3 proposed based on the problems of the patent documents 1 and 2 as described above, the method of this document requires a large amount of pure water more than 1000 times the slag. As it is not convenient. Moreover, in patent document 3, pure water is used as a solvent and the elution amount of Ca ^<2+> ion is converted from a pH measurement result. Next, when estimating the situation when slag is added to seawater, the pH is calculated by converting the elution amount of Ca ²⁺ ions into the OH ⁻ elution amount. Further, after the pH reaches 9.8, all Mg ²⁺ ions in the sea react with OH ⁻ eluted from the slag to precipitate Mg (OH) ₂ and completely deposit Mg (OH) _2. Assuming that the pH rises again, the buffering effect of seawater (the effect of suppressing the increase in pH) is reproduced. However, this derivation has a problem that only Mg (OH) ₂ precipitation is considered as a buffering action of seawater.

Here, the pH value when 5 ml of Ca (OH) ₂ saturated solution (pH 12.5 was confirmed by measurement in advance) was put in 2 L of pure water and seawater was measured. On top of that, the calculated pH when assuming that seawater does not have a buffering effect as well as pure water (that is, only a Ca (OH) ₂ saturated solution having a pH of 12.5 is diluted) is plotted on the horizontal axis and the vertical axis. A plot of the measured pH is shown in FIG. According to FIG. 1, when seawater is used as the solvent, the pH is 9.5 to 9.8 or less, which acts as a buffer effect due to Mg (OH) ₂ precipitation, and therefore, even in this low pH region, the buffer effect. It is clear that is working. This is considered to be due to a buffering action due to CaCO ₃ precipitation represented by the following formula (1).
Ca (OH) ₂ + H ₂ CO ₃ → CaCO ₃ + 2H ₂ O (1)

Free CaO of slag becomes Ca (OH) _{2 and the} eluted Ca ²⁺ ions form carbonate ions and calcium carbonate generated from carbonate H ₂ CO ₃ , and OH ⁻ from the slag counteracts H ⁺ generated from carbonate. As a result, an increase in pH is suppressed.
From the above points, the use of pure water as the solvent for the dissolution test as in Patent Document 3 is a considerable overestimation and a severe condition in reproducing the OH ⁻ concentration increase of seawater due to the influence of slag. it is conceivable that.

The object of the present invention is to solve the above-mentioned problems of the prior art, and to accurately and easily determine the amount of OH ^- load (the amount of increase in seawater pH) given to seawater from the sea surface to the visible water depth when slag is introduced into the sea. It is to provide a method that can be predicted.
Another object of the present invention is to provide a method capable of preparing or selecting a slag for charging into the sea area that does not cause white turbidity in seawater from the sea surface to the visible water depth region using the prediction method.

The gist of the present invention for solving the above problems is as follows.
[1] A method for predicting the amount of OH ^- load that slag gives to seawater from the sea surface to the visible depth region when any arbitrary slag A is introduced into the sea area,
The particle size distribution of the slag A is divided into a plurality of particle size bands g, and the slag of each particle size band g is obtained with a specific surface area s and a settling time t from the sea surface to the visible water depth when thrown into the sea area. The unit slag mass from the slag in the sea surface to the visible water depth region when any one particle size zone g _x is selected from g and slag A is thrown into the sea according to the procedures (i) to (iii) below A method for predicting the OH ^- loading amount of seawater by introducing slag , wherein the OH ^- elution amount D per hit is obtained.
(I) Tsubudotai g _x slag was subjected to dissolution test with specimens, based on pH measurements when immersed slag seawater, seawater per unit slag weight of slag Tsubudotai g _x OH ^- concentration An increase rate v _x is obtained.
(Ii) Tsubudotai g specific surface area _x of slag s _x and per unit slag weight OH ^- based on the concentration increased speed v _x, OH per unit specific surface area of slag A ^- determine the concentration increasing speed amount, the unit ratio OH per surface area ^- the density increasing speed component, by multiplying the specific surface area s of each slug of all other Tsubudotai g except Tsubudotai g _x, of Tsubudotai g _x other than all other Tsubudotai g The OH ^- concentration increase rate v per unit slag mass of each slag is obtained.
(Iii) For slag of each particle size zone g, [OH ^- concentration increasing speed v] × [sedimentation time t from the sea surface to visible water depth] × [ mass ratio w in slag A] = OH ^— elution amount d is obtained. The total of OH ^- elution amount d of slag in all the particle size bands g is obtained as OH ^- elution amount D per unit slag mass .

[2] The prediction method of [1 ] above, wherein the slag of the particle size zone g _x has a specific surface area of 0.5 m ² / kg or more, and the prediction method of OH ^- load amount of seawater by slag injection .
[3] In the prediction method of [1] or [2 ] above, in an elution test using a slag having a particle size band g _{x as} a specimen, the slag is immersed in seawater having a mass of 3 to 20 times the slag mass. A method for predicting OH ^- loading amount of seawater by adding slag, wherein pH is measured while applying stirring at a rotational speed of 300 rpm, and an OH ^- concentration increasing rate is obtained from this pH change .
[4] In the prediction method of any one of [1] to [3] above , based on the OH ^- elution amount D per unit slag mass , [OH-elution amount D] × [slag injection rate into the sea area] = A method for predicting the OH ^- load amount of seawater by introducing slag, wherein the actual OH ^- load amount F is obtained .

[5] a [1] to [3] or a method for the preparation of waters introduced for slag using a prediction method, a sea-on, characterized in that performing particle size control of slag proceed as follows (a) A method for preparing slag.
(A) per unit slag weight OH ^- for the elution amount D, sets the reference value D ₀ that does not cause turbidity in sea surface to visible depth region upon slag charged, OH per unit slag weight calculated ^- elution volume D are formed so that the reference value D ₀ following, the particle size adjustment of the slag.
[6] [1] ~ is any method of selecting the waters turned for slag using a prediction method of [3], waters charged for slag and performing selection of slag proceed as follows (a) Selection method.
(A) per unit slag weight OH ^- for the elution amount D, sets the reference value D ₀ that does not cause turbidity in sea surface to visible depth region upon slag charged, OH per unit slag weight calculated ^- elution volume D is selected the reference value D ₀ following slug.
[7] A method for preparing a slag for seawater input, which is a method for preparing a slag for seawater input using the prediction method of [4] above, wherein the particle size of the slag is adjusted according to the following (b).
(B) For the actual OH ^- load amount F, when a slag is introduced, a reference value F ₀ that does not cause white turbidity in the sea surface to visible water depth region is set, and the calculated actual OH ^- load amount F is less than the reference value F ₀ The slag particle size is adjusted so that
[8] A method for selecting a slag for entering the sea using the prediction method of [4] above, wherein the slag is selected according to (b) below.
(B) For the actual OH ^- load amount F, when the slag is introduced, a reference value F ₀ that does not cause white turbidity in the sea surface to visible water depth region is set, and the calculated actual OH ^- load amount F is less than the reference value F ₀ Select slag.

According to the seawater OH ^- load amount prediction method of the present invention, a simple dissolution test that can be performed using a relatively small amount of seawater as a solvent is performed on slag in some of the particle size zones of the target slag. It may be carried out by, moreover OH by using a pure water as a solvent ^- it is possible to prevent also overestimate the increase in concentration, giving slag seawater sea to visible depth region when charged with slag waters OH ^- The amount of load (the amount of seawater pH increase) can be predicted accurately and simply.
In addition, according to the method for preparing or selecting a slag for sea area input according to the present invention, by using the prediction method, a slag for sea area input that does not cause white turbidity in seawater from the sea surface to the visible water depth region can be accurately and simply prepared. Can be selected.

Graph showing measured pH when ₂ mL of Ca (OH) ₂ saturated solution is added to ₂ L of pure water and seawater Graph showing the transition of pH when leaching tests were conducted using seawater as a solvent for slag of specific particle size bands (slags of three particle size bands) extracted from steelmaking slag Graph showing the pH in FIG. 2 in terms of OH ^- concentration FIG. 3 is a graph showing the OH ^- concentration increasing rate of seawater per unit time and unit slag amount as a result of FIG. 3 in relation to the specific surface area of slag. Graph showing the particle size distribution (level a, b) of any two steelmaking slags Sedimentation time and depth of OH ^- concentration increase up to 5 m depth by slag particle size zone, and mass ratio of slag by particle size zone in steelmaking slag shown in FIG. Graph showing OH ^- elution amount by particle size band FIG. 5 is a graph showing the calculated amount of OH ^- elution in the region from the sea surface to the visible water depth (water depth 5 m) for steelmaking slag having a particle size distribution of levels a and b in FIG.

There is no special restriction on the slag that is the subject of the present invention. Typical examples of slag include steel slag (slag generated in the steel manufacturing process), but the slag is not limited to this. For example, slag of metals other than steel or smelting slag, waste gas It may be a molten slag, a waste incineration ash molten slag, or the like.
Examples of steel slag include blast furnace slag, steelmaking slag, ore smelting reduction slag, and examples of steelmaking slag include hot metal pretreatment slag (dephosphorization slag, desiliconization slag, desulfurization slag, etc.), converter desorption. Examples include charcoal slag, cast slag, and electric furnace slag. Among these, steelmaking slag has a relatively high free CaO content, and on the other hand, sea area utilization is increasing. Therefore, the method of the present invention is particularly useful as a method for predicting OH ^- load when steelmaking slag is used in the sea area. It can be said that it is useful.

In order to expand the use of slag such as steelmaking slag containing free CaO in the sea area while ensuring safety, the inventors have determined what pH of the seawater is. The possibility of increasing the degree and the occurrence of white turbidity due to the increase was examined.
First, the calculation method of the OH ^- load amount (the amount of increase in seawater pH) given to seawater when slag was introduced into the sea area was examined.
The increase in pH of seawater due to slag injection can be expressed by the following equation (2).
CaO + H ₂ O → Ca (OH) ₂ → Ca ²⁺ + 2OH ⁻ (2)
That is, CaO (calcium oxide) in the slag reacts with moisture to change to Ca (OH) ₂ (calcium hydroxide), and this Ca (OH) ₂ dissolves in seawater to cause Ca ²⁺ (calcium ions) and OH. ^- by generating (hydroxide ion), and alkaline.

The dissolution test for measuring the pH increase of seawater due to slag shown below was based on JIS-K-0058-1: 2005 “Testing method for chemical substances of slags—Part 1: Elution test method”. In this dissolution test, a solvent (seawater) equivalent to 10 times the mass of the target slag is used, and the pH is measured while stirring at 200 rpm is maintained. By using seawater as the solvent, it is possible to accurately reproduce the pH increase of seawater when slag is introduced into the actual sea area.
The steelmaking slag previously crushed is air-dried in an environment of 20 ° C. and a relative humidity of 50%, and the steelmaking slag is sieved to a size of 2 mm to 4.75 mm or less, 9.5 mm to 13.2 mm or less, 30 mm to 50 mm or less. Three types of particle size slag were taken out, and pH was measured for each slag of each particle size zone.

In the dissolution test, 200 g of slag was collected from the slag of each particle size zone, this slag was immersed in 2 L of seawater contained in a beaker, and stirred at a rotational speed of 200 rpm with a rotary blade stirrer, a pH meter Was used to measure the pH of the solvent. FIG. 2 shows the pH measurement results of the slag in each particle size band, and it can be seen that there is a difference in pH change depending on the difference in the slag particle size. That is, it can be seen that the finer the slag particle size, the greater the change in pH and the higher the final pH value. FIG. 3 shows the pH of FIG. 2 converted to OH ⁻ concentration. From Figures 2 and 3, pH ≦ 9.5 ^-: linearly OH respect (OH concentration of about 3.2 × ^{10 -5} mol / L) to the time ^- that concentration increases, and the straight line It can be seen that the inclination is larger as the slag particle size is smaller. The slope of this straight line corresponds to the OH ^- concentration increase rate of seawater per unit slag amount.

FIG. 4 shows the OH ^- concentration increase rate of seawater per unit time and unit slag amount as a result of FIG. 3 in relation to the specific surface area of slag. Here, in determining the specific surface area of the slag in each particle size zone, the shape of the slag was assumed to be a sphere, and the slag density was the true specific gravity (3.5 t / m ³ ) of the slag alone. Moreover, the average particle size (average value of particle size zone upper limit value and lower limit value) of each particle size zone was used as the slag particle size.
According to FIG. 4, it can be seen that the specific surface area of slag and the OH ^- concentration increasing rate are in a proportional relationship. That is, it is concluded that the OH ⁻ concentration increase rate of seawater per unit time and unit slag specific surface area is substantially constant, and the specific surface area increases as the slag particle size becomes finer, so that the OH ⁻ concentration increase rate increases.

From the above points, the amount of OH ⁻ eluted from the target slag A into the seawater can be predicted as follows. That is, the slag of a certain particle size band g _x extracted by sieving the target slag A is subjected to the above elution test using seawater as a solvent to measure the pH, and from this pH measurement result Then, the OH ^- concentration increase rate v _x of the slag in the particle size zone g _x is obtained. The specific surface area and OH slag ^- for concentration increase rate is proportional to (4), Tsubudotai specific surface area of g _x slag s _x and OH ^- from the density increase rate v _x, per unit specific surface area of slag A The OH ^- concentration increase rate can be determined. Then, per the unit specific surface area OH ^- concentration increased speed amount, by multiplying the specific surface area s of each slug other granularity band g other than the particle size range g _x of slag A, Tsubudotai g _x other than the other The OH ⁻ concentration increase rate v of each slag in the particle size zone g can be obtained, and the OH ⁻ elution amount from the slag A to the seawater can be obtained from the OH ⁻ concentration increase rate v of each particle size zone g.
As described above, by performing a pH measurement test of slag using seawater as a solvent, it is possible to accurately and quickly measure the OH ^- concentration increase rate from the measured pH value of the solvent, and the obtained OH ^- concentration increase From the speed and the specific surface area of the slag (that is, the particle size distribution of the slag), it was found that the OH ^- elution amount (OH ^- concentration increase amount) when the slag was introduced into the sea area could be predicted.

Next, the pH change of seawater when slag was introduced into the sea area was examined from the viewpoint of slag particle size.
First, the sedimentation behavior of slag particles when put into seawater was examined. This is because the slag with a smaller particle size has a higher OH ^- concentration increase rate in seawater, which can be the main cause of white turbidity. Therefore, when seeking an increase in seawater pH due to slag injection, slag with a small particle size that affects white turbidity. This is in order to understand how much time is drifting near the sea surface. Here, since a region deeper than the visible water depth in the sea cannot be visually confirmed from above the sea surface, the region from the sea surface to the visible water depth may be considered as a clouding phenomenon that becomes a problem immediately after the construction of the slag. In a normal sea area, the visible water depth in the sea is about 5 m. Here, the water depth up to 5 m is defined as the visible water depth. Therefore, it is presumed that slag with a high sedimentation velocity immediately sinks to a depth of 5 m or more, so that the influence on the pH increase near the sea surface will be small.

The sedimentation behavior of slag particles was determined using Stokes' formula, Allen's formula, and Newton's formula widely used for sedimentation of fine particles. The following equation (3) shows the Stokes equation, equation (4) shows the Allen equation, and equation (5) shows the Newton equation. Here, the Stokes equation is applied when the number of ray nozzles <1, the Allen equation is applied when 1 ≦ the number of ray nozzles ≦ 500, and the Newton equation is applied when the number of ray nozzles> 500.
Vt = (ρs−ρ) × g × (D2 / 18μ) (3)
Vt = [4/225 × (ρs−ρ) 2 × g2 / ρμ] 1/3 × D2 (4)
Vt = [3 × (ρs−ρ) × g × (D / ρ)] 1/2 (5)
Where Vt: particle end velocity (cm / s)
ρs: density of particles (g / cm ³ )
ρ: Density of liquid (g / cm ³ )
μ: Viscosity coefficient of liquid (g / cm · s)
D: Particle size (cm)
g: Gravity acceleration (cm / s ² )
Table 1 shows the result of dividing the particle size distribution of the steelmaking slag into a plurality of particle size bands and calculating the slag sedimentation rate in each particle size band. Here, the density of the steelmaking slag was calculated as 3.5 t / m ³ (3.5 g / cm ³ ). Moreover, the average particle size (average value of particle size zone upper limit value and lower limit value) of each particle size zone was used as the slag particle size.

As shown in Table 1, it can be seen that the smaller the slag particle size, the longer the time required for sedimentation to a depth of 5 m. Here, about the slag of each particle size zone of Table 1, the OH ^- concentration increase speed is multiplied by the sedimentation time to the water depth of 5 m (visible water depth), so that the slag sea surface to the water depth of 5 m (visible water depth) of each particle size zone. The amount of increase in OH ^- concentration at can be determined.
Therefore, regarding the slag of each particle size zone of the target slag A, each “OH ^— concentration increase rate v” includes “sedimentation time t from the sea surface to visible water depth (5 m depth)” and “mass ratio in the slag A” By multiplying "w" and calculating the sum of all the particle size bands of the value, the amount of OH ^- concentration increase from the sea surface to the visible water depth (5 m depth) of slag A, that is, the amount of OH ^- elution into seawater can be determined. .

Therefore, in the present invention, when an arbitrary slag A is introduced into the sea area, the OH ^- load amount that the slag A gives to the seawater in the sea surface to the visible water depth region is predicted as follows. Hereinafter, this will be described with reference to FIGS. FIG. 5 shows the particle size distribution (level a, b) of any two steelmaking slags corresponding to slag A. Level a is a slag selected using a sieve of 13 mm below and 85 mm as the sieve mesh, and level b is a slag selected using a sieve of 30 mm below and 85 mm as the sieve mesh. FIG. 6 shows the sedimentation time and the OH ^- concentration increase rate to a depth of 5 m for each slag particle size band, and the mass ratio of slag by particle size band in the steelmaking slag shown in FIG. Mass ratio) and OH ^- elution amount by particle size band.

In the present invention, first, the particle size distribution of the target slag A is divided into a plurality of particle size bands g. In the example shown in FIG. 6, steelmaking slag having the particle size distribution of levels a and b in FIG. 5 is divided into 12 particle size bands g (0.075 mm or less, 0.075 mm to 0.15 mm or less, 0.15 mm to 0.3 mm or less, 0.3 mm). Ultra-0.6mm or less, 0.6mm or more-1.18mm or less, 1.18mm or more -2.36mm or less, 2.36mm or more -4.75mm or less, 4.75mm or more -9.5mm or less, 9.5mm or more -13.2mm or less, 13.2mm or more- 19mm or less, more than 19mm -26.5mm or less, more than 26.5mm -85mm or less).
And about the slag of each particle size zone g, the specific surface area s (m < ² > / kg) and the sedimentation time t (minute) from the sea surface at the time of throwing into a sea area to visible water depth are calculated | required. Usually, in the calculation of the specific surface area s of the slag of each particle size zone g, the shape of the slag is assumed to be a sphere, and the slag density is the true specific gravity (3.5 t / m ³ ) of the slag alone. Moreover, what is necessary is just to use the average particle diameter (Average value of a particle size zone | band upper limit value and a lower limit) for each slag particle size.
Moreover, the sedimentation time t from the sea surface of the slag of each particle size zone g to the visible water depth (for example, 5 m water depth) is shown in Table 1 and FIG. 6 (A) according to the Stokes equation, Allen equation and Newton equation mentioned above. ).
Here, the method of determining the “visible water depth” of the sea area may be a method of measuring seawater transparency using a commonly used transparency plate, lowering the transparency plate into the sea, and obtaining a water depth at which the transparency plate can be seen from above the sea surface.

OH from slag in the sea surface to visible water depth region when arbitrary sizing zone g _x is selected from a plurality of sizing zones g and slag A is thrown into the sea area according to the following procedures (i) to (iii) ^- obtaining the elution amount D.
(I) An elution test using a slag having a particle size band g _{x as} a specimen is performed, and an OH ^- concentration increase rate v _x of seawater is obtained based on a pH measurement result when the slag is immersed in seawater.
Based on the concentration increasing rate _{v x,} OH per unit specific surface area of slag A ^{- -} (ii) Tsubudotai _g specific surface area _{s x} and OH slug _x determine the concentration increasing speed amount, OH per the unit specific surface area ^- the concentration rate of increase amount, Tsubudotai g _x other than that multiplied with the specific surface area s of each slug other granularity band g, Tsubudotai g OH of each slug other granularity band g other than _x ^- concentration increased velocity v Ask for.
(Iii) For the slag of each particle size band g, [OH ^- concentration increasing speed v] × [sedimentation time t from the sea surface to visible water depth] × [proportion w in slag A] = OH ^— elution amount d OH slag of all particle size band g ^- obtained as elution D ^- the sum of the elution amounts d OH.

In the present invention, only the slag of one particle size zone g _x of the slag A is subjected to a dissolution test to perform pH measurement. The selected particle size band g _x may be any of a plurality of particle size bands g, and in the case of FIG. 6, it may be any of the 12 particle size bands g. However, in the present invention, the specific surface area s _x slug Tsubudotai g _x, OH seawater based on pH measurements ^- Higher levels velocity v _x, per unit specific surface area in the "slug A OH ^- concentration increasing rate min ”(Corresponding to the slope of the straight line X (= passing through the origin) shown in FIG. 4), it is more difficult to select a particle size zone made of slag with a large specific surface area as the particle size zone g _x. Is preferable from the viewpoint of reducing the size. Specifically, the slag of the selected particle size band g _x preferably has a specific surface area of 0.5 m ² / kg or more.

In the elution test (tank leaching test) using the slag of the particle size zone g _x in the above (i) as a specimen, the slag is immersed in seawater having a mass 3 to 20 times the slag mass, and a rotary blade stirrer is used. It is preferable to measure the pH with stirring. If the mass of seawater used as a solvent is less than 3 times the mass of slag, the pH immediately increases to 9.5 after the start of the dissolution test, which may hinder measurement. On the other hand, if it exceeds 20 times, the scale of the apparatus becomes large and it is not easy as a test method. From such a viewpoint, the more preferable amount of seawater is about 5 to 10 times the slag mass. In addition, stirring is desirably performed at a rotational speed of about 50 to 300 rpm, preferably about 100 to 200 rpm, in the sense that the turbulent state of the ocean current occurring in the actual sea area is also reproduced in the dissolution test. The other test conditions for the dissolution test are preferably based on JIS-K-0058-1: 2005 “Testing methods for chemical substances of slags—Part 1: Dissolution test method”.
The pH value of the slag measured particle size range g _x In this dissolution test OH ^- in terms of concentration, OH seawater as shown in Figure 3 ^- to determine the concentration increasing speed.

Figure 4 on the specific surface area s and OH slag as shown ^- concentration increased velocity v is proportional, time unit, seawater OH per unit slag specific surface area ^- concentration rate of increase is substantially constant. In the above (ii), Tsubudotai g specific surface area of _x slag s _x and OH ^- expressed in ^- "concentration rate of increase amount OH per unit specific surface area of slag A" (Fig. 4 from the density increase rate v _x, The straight line X (corresponding to the inclination of the passing through the origin) is obtained. Then, by multiplying this “OH ^- concentration increasing rate per unit specific surface area in slag A” by the specific surface area s of each slag other than the particle size band g _x of slag A, the particle size band g The OH ^- concentration increase rate v of each slag in the particle size band g other than _x is obtained.

And in said (iii), about the slag of each particle size zone g, [OH ^- concentration increase speed v (mol / min * slag 1kg)] x [sedimentation time t (min) from the sea surface to visible water depth] x [ percentage slag a w (weight%)] = OH ^- determined quantity eluted d, OH slug of all particle size band g ^- obtained as elution D ^- the sum of the elution amounts d OH.
In FIG. 6, the [OH ^- concentration increase rate v (mol / min · slag 1 kg)] of each slag g is shown in FIG. 6 (a), and the slag of each slag g [from sea level to visible water depth] The settling time t (min)] is FIG. 6 (a), and the [ratio w (mass%) in the slag A] of the slag of each particle size band g is FIG. 6 (c). About slag, by multiplying those values, OH ^- elution amount d from slag of each particle size zone g from the sea surface to the visible water depth region when slag A is introduced into the sea area, that is, FIG. I want. And the sum of OH ^- elution amount d from slag in each particle size zone g (= Σ (v × t × w)) is OH from slag in the sea surface to visible water depth region when slag A is introduced into the sea area. ^- it comes to elution D.
In the present invention, this OH ^- elution amount D is regarded as the OH ^- load amount that slag gives to seawater in the sea surface to the visible water depth region when slag A is introduced into the sea region, for example, the occurrence of cloudiness in the sea surface to visible water depth region It is used as an index for determining the presence or absence of the.

FIG. 7 shows the sum of OH ^- elution amount d from the slag of each particle size zone g shown in FIG. 6D for the steelmaking slag of the levels a and b of FIGS. 5 (a) and 5 (a). The OH ^- elution amount D from the slag from the sea surface to the visible water depth region when the is introduced into the sea area. According to this, since the ratio of fine slag particles having a large OH ^- concentration increasing rate and settling time is smaller in the level b slag than the level a slag, the OH ^- elution amount D is the level a. It is about 1/5 of slag.

In addition, as will be described later, whether or not white turbidity occurs from the sea surface to the visible water depth region when slag is actually added depends on the OH ^- elution amount D predicted by the present invention and the slag injection rate (t / hr), based on the calculated OH ^- elution amount D (mol / slag 1 kg) and a predetermined slag charging rate (t / hr), further [OH ^- elution amount D (mol / slag 1 kg) ] × [slag injection speed into sea area (t / hr)] = actual OH ⁻ load amount F (mol / hr) may be obtained, and this actual OH ⁻ load amount F is determined, for example, from the sea surface to the visible water depth region. It may be used as an index for determining whether or not white turbidity occurs.

Next, the preparation method or selection method of the slag for sea area input by this invention is demonstrated. In this method for preparing or selecting a slag for use in the sea area, the prediction method of the present invention as described above is used, and the OH ^- elution amount D or [OH ^- elution amount D] calculated by this prediction method × [ Slag injection speed] = actual OH ⁻ load amount F is used to prepare or select slag.
As one method, for the OH ^- elution amount D, a reference value D ₀ that does not cause white turbidity from the sea surface to the visible water depth region when slag is introduced is set. In this case, the process for the preparation of waters introduced for slag, the OH is calculated by the prediction method ^- as elution amount D becomes the reference value D ₀ following, the particle size adjustment of the slag. Usually, in this particle size adjustment, slag is sieved to remove fine slag particles. Further, in the method of selecting the waters turned for slag, OH is calculated by the prediction method ^- selecting the elution amount D is the reference value D ₀ following slag as slag suitable for waters on.

Here, whether or not white turbidity is generated from the sea surface to the visible water depth when slag is actually added is determined by the OH ^- elution amount D predicted by the present invention and the slag injection speed (t / hr). . Taking the steelmaking slag of level a and b shown in FIG. 7 as an example, the OH ^- elution amount D of the slag of level a is 1.04 × 10 ⁻³ mol / kg of slag, and the OH ^- elution amount of slag of level b. D is 1.98 × 10 ⁻⁴ mol / kg of slag, but if the slag of level a is charged at a charging speed of 200 t / hr, it is assumed that white turbidity does not occur from the sea surface to the visible water depth region. Of slag (OH ^- elution amount D is about 1/5 of level a slag) at about 3 times the input speed (600 t / hr) will not cause white turbidity in the sea surface to visible water depth region. . Therefore, the reference value D ₀ is preferably determined by considering the actual input rate of the slag.

For example, when a certain steelmaking slag has an OH ^- elution amount D determined by the prediction method of the present invention is α (mol / slag 1 kg), and this steelmaking slag is thrown into the sea area at a feed rate β (t / hr) When no turbidity in sea surface to visible depth region, it is possible to set the reference value D ₀ as follows.
-Slag charging speed: When β (t / hr) or less, standard value D ₀ : α (mol / slag 1 kg)
・ Slag charging speed: When β exceeds (t / hr), 2 × β (t / hr) or less, reference value D ₀ : 0.5 × α (mol / slag 1 kg)
・ Slag charging speed: In the case of more than 2 × β (t / hr) and 3 × β (t / hr) or less, the reference value D ₀ : 0.33 × α (mol / slag 1 kg)

As another method, [OH ^- elution amount D (mol / slag 1 kg)] × [slag injection speed (t / hr) into sea area] = actual OH ^- load amount F (mol / hr), slag the reference value F ₀ that does not cause turbidity in sea surface to visible depth region when the charged may be set. In this case, in the method for preparing the slag for charging the sea area, the actual OH ^- load amount F obtained from the OH ^- eluting amount D (mol / slag 1 kg) and a predetermined slag charging speed (t / hr) is the reference value F _0. The particle size of the slag is adjusted so as to be as follows. Usually, in this particle size adjustment, slag is sieved to remove fine slag particles. Further, in the method of selecting the waters turned for slag, real OH ^- selecting as slag load F is suitable for the reference value F ₀ following slag waters on.
For example, when a steelmaking slag has an OH ^- elution amount D determined by the prediction method of the present invention is α (mol / slag 1 kg), and the steelmaking slag is charged at a charging speed β (t / hr), the sea level Assuming that white turbidity does not occur in the visible water depth region, α (mol / slag 1 kg) × β (t / hr) = α × β (mol / hr) can be set as the reference value F ₀ .

Claims (8)

A method for predicting the amount of OH ^- load that slag gives to seawater from the sea surface to the visible water depth when any arbitrary slag A is introduced into the sea area,
The particle size distribution of the slag A is divided into a plurality of particle size bands g, and the slag of each particle size band g is obtained with a specific surface area s and a settling time t from the sea surface to the visible water depth when thrown into the sea area. The unit slag mass from the slag in the sea surface to the visible water depth region when any one particle size zone g _x is selected from g and slag A is thrown into the sea according to the procedures (i) to (iii) below A method for predicting the OH ^- loading amount of seawater by introducing slag , wherein the OH ^- elution amount D per hit is obtained.
(I) Tsubudotai g _x slag was subjected to dissolution test with specimens, based on pH measurements when immersed slag seawater, seawater per unit slag weight of slag Tsubudotai g _x OH ^- concentration An increase rate v _x is obtained.
(Ii) Tsubudotai g specific surface area _x of slag s _x and per unit slag weight OH ^- based on the concentration increased speed v _x, OH per unit specific surface area of slag A ^- determine the concentration increasing speed amount, the unit ratio OH per surface area ^- the density increasing speed component, by multiplying the specific surface area s of each slug of all other Tsubudotai g except Tsubudotai g _x, of Tsubudotai g _x other than all other Tsubudotai g The OH ^- concentration increase rate v per unit slag mass of each slag is obtained.
(Iii) For slag of each particle size zone g, [OH ^- concentration increasing speed v] × [sedimentation time t from the sea surface to visible water depth] × [ mass ratio w in slag A] = OH ^— elution amount d is obtained. The total of OH ^- elution amount d of slag in all the particle size bands g is obtained as OH ^- elution amount D per unit slag mass . Slag Tsubudotai _{g x} is characterized by a specific surface area of 0.5 m ² / kg or more, the sea water by the slag on of claim 1 OH ^- load prediction method. In the dissolution test using slag of the particle size band g _{x as} a specimen, slag is immersed in seawater having a mass 3 to 20 times the slag mass, and the pH is measured while stirring at a rotational speed of 50 to 300 rpm. The method for predicting the OH ^- load amount of seawater by introducing slag according to claim 1, wherein an OH ^- concentration increase rate is obtained from a change . OH per unit slag mass ⁻ Based on the dissolution amount D, [OH-elution amount D] × [slag injection speed into the sea area] = actual OH ⁻ The load amount F is obtained, and OH of seawater by slag injection according to any one of claims 1 to 3, ⁻ How to predict the load. Claim 1 is a method for the preparation of waters introduced for slag using a prediction method according to any one of 3, the following (a) to follow the waters turned for slag and performing particle size control of the slag Preparation method.
(A) per unit slag weight OH ^- for the elution amount D, sets the reference value D ₀ that does not cause turbidity in sea surface to visible depth region upon slag charged, OH per unit slag weight calculated ^- elution volume D are formed so that the reference value D ₀ following, the particle size adjustment of the slag. A claim 1-3 any one Selection waters turned for slag using a prediction method according to the selection of waters introduced for slag and performing selection of slag proceed as follows (a) Method.
(A) per unit slag weight OH ^- for the elution amount D, sets the reference value D ₀ that does not cause turbidity in sea surface to visible depth region upon slag charged, OH per unit slag weight calculated ^- elution volume D is selected the reference value D ₀ following slug. It is a preparation method of the slag for sea area input using the prediction method of Claim 4, Comprising: The particle size adjustment of slag is performed according to following (b), The preparation method of the slag for sea area input is characterized by the above-mentioned.
(B) Real OH ⁻ Regarding load F, reference value F that does not cause white turbidity from the sea surface to the visible water depth when slag is introduced ₀ To calculate the actual OH ⁻ Load amount F is reference value F ₀ The particle size of the slag is adjusted so as to be as follows. A method for selecting a slag for sea area input, which is a method for selecting a slag for sea area input using the prediction method according to claim 4, wherein the slag is selected according to the following (b).
(B) Real OH ⁻ Regarding load F, reference value F that does not cause white turbidity from the sea surface to the visible water depth when slag is introduced ₀ To calculate the actual OH ⁻ Load amount F is reference value F ₀ Select the following slag.

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