JP2007022817A - Treating method of steelmaking slag - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a treating method of steelmaking slag enabling a highly productive stabilizing treatment of steelmaking slag at a low treating cost, and capable of reducing the amount of CO<SB>2</SB>emission. <P>SOLUTION: In a treating method of steelmaking slag in which CaO in the steelmaking slag is carbonated by supplying CO<SB>2</SB>gas while mechanically stirring the steelmaking slag, the steelmaking slag is stirred under a condition wherein particles having a diameter of 10-40 mm are contained in the slag, and the space filling rate η to the stirring vessel is set at 0.03-0.15 to achieve high productivity. Further, η, a vessel diameter D, a number of rotation ω, a water content M, a free lime concentration before the treatment, and a target free lime concentration after the treatment are specified. Further, it has become possible to specify the relation between D and ω, from a target value of the treatment productivity Q, a free lime concentration before the treatment, and a target free lime concentration after the treatment. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for processing steelmaking slag, and promotes the reuse and effective use of steelmaking slag, and contributes to the reduction of natural environment destruction by providing natural crushed stone and aggregate substitutes. The technology that contributes to the reduction of carbon dioxide emissions in the steelmaking process.

In the steelmaking process, lime source is added as a refining agent, and by increasing the mass concentration ratio of CaO and SiO ₂ (hereinafter abbreviated as basicity), impurities in steel such as phosphorus and sulfur are transferred to the slag side. Slag refining is performed to generate easy slag and remove it. In general, the slag refining capacity increases as the basicity increases. However, when a large amount of CaO is added to increase the basicity, CaO, which is a substance having a high melting point of 2500 ° C, is in an unmelted state, and SiO ₂ etc. It may remain unreacted with other slag components. Further, when the basicity is increased, if the CaO concentration reaches the solubility or higher, it remains in an unmelted state. Moreover, when processing is performed in a short time in order to increase productivity, it results in increasing the unreacted amount of CaO. Therefore, although in the slag after the treatment completion free of CaO remains, which, and water vapor in the atmosphere, react with water, the volume by the reaction of _{CaO + H 2 O → Ca (} OH) 2 is 2 Since it expands twice, when it is recycled as a civil engineering material, expansion and weathering become a problem. In addition, since Ca (OH) ₂ is a strong alkali, when it reacts with rainwater, it generates strong alkaline water, killing organisms, clouding the sea and lakes, and destroying the environment.

  Thus, steelmaking slag inevitably contains free CaO depending on the required function, and its stabilization is a problem. Conversely, if the free CaO content can be modified to a more stable compound, for example, it can be effectively used as a civil engineering and building material as an alternative to natural crushed stone, where collection sites have been depleted in recent years. The place that contributes to formation is also great.

The idea of stabilizing this free CaO content as a calcium carbonate (CaCO ₃ ) -based compound by carbonation treatment is inherently stable as a natural source of marble and limestone with CaCO ₃ as the main component. This is a very natural way of thinking. This method is also preferable for reducing the amount of CO ₂ emitted because it can fix CO ₂ in steelmaking and industrial exhaust gas.
Therefore, there have been many proposals for a slag processing method using this principle.

For example, in Patent Document 1, in order to use a converter slag for concrete aggregates or the like, a converter slag in a surface state from dry saturation to wet is in a range of -10 ° C to 220 ° C. Thus, a method is shown in which carbonation is performed by contacting with a gas mainly composed of air containing 10% or more of carbon dioxide under conditions of 20 to 100% humidity.
However, as will be described later, the reaction stops midway, and it is difficult to reduce the free lime concentration to 1% by mass or less.

Steelmaking slag is generated in large quantities, and it is necessary to make it a method that can cope with this and is sufficiently productive and industrially meaningful. Therefore, as an improvement of the method disclosed in Patent Document 1, it has been proposed to perform the reaction at a high temperature of 800 ° C. to 300 ° C. (see, for example, Patent Document 2).
However, as will be described later, even if the temperature is high between 800 ° C. and 300 ° C., the reaction stops midway, and it is difficult to reduce the free lime concentration to 1% by mass or less.

Further, for example, Patent Document 3 discloses a method of generating CaCO ₃ by causing a solid water particle assembly containing CaO or Ca (OH) ₂ to have an attached water film and performing a carbonation reaction with an exhaust gas containing CO _2. It is stated. Furthermore, a method is described in which the carbon dioxide in the exhaust gas is fixed thereby to reduce the discharged carbon dioxide. However, it has been shown that the process of producing a 1 m ³ slag mass takes a long time of 24 hours.
Moreover, in order to increase the reaction rate, it is stated that the target is essentially only small particles of 5 mm or less, preferably 1 mm or less, or that a new surface is generated by crushing in advance. . However, Patent Document 3 only discloses that the particle size is reduced in order to reduce the free lime concentration, and restricting the particle size requires further crushing and pulverization of the particles. It is necessary to add crushing and crushing equipment, and the processing cost is expensive, and it is not possible to use it when there is a standard particle size distribution like a roadbed material with only the powder content, and it is necessary to add crushed stone of a predetermined particle size etc. There was a problem that there was.
In addition, as will be described later, there is a problem that even if the crushing process is performed in advance, the reaction is stagnant and the reaction does not proceed any further.

  For example, Patent Document 4 discloses a method in which steelmaking slag is subjected to an aging treatment in a water vapor atmosphere under atmospheric pressure, and further maintained for 1 hour or longer in a mixed gas atmosphere of water vapor and CO2 gas. However, this method requires a new processing facility for steam aging. In general, steam aging also takes several days, and the productivity is low, so it can be applied only partially to slag generated in large quantities.

For example, Patent Document 5 discloses a method of reacting steelmaking slag with water vapor and CO ₂ under pressure. It is said that the hydration reaction (CaO + H ₂ O → Ca (OH) ₂ ) is promoted by the effect of pressurization, and the expansion of the slag particles progresses and the carbonation also proceeds.
However, this method requires a large pressure treatment facility, and enormous facility costs and running costs are required. Also, maintenance for maintaining the soundness of the equipment is not easy.
As described above, the conventional processing method has not succeeded in finding a method for obtaining sufficiently high productivity at low cost, and a method for stabilizing the total amount of steelmaking slag with high productivity has been found. Absent.
JP 50-41772 A JP 52-129672 A Japanese Patent No. 3248514 JP-A-8-269282 JP-A-6-158124

It is an object of the present invention to provide a method for carbonizing a steelmaking slag generated in a large amount with high productivity and stabilizing the expansion and elution pH at a low level. Also, as a side effect, the CO ₂ is immobilized, it is an object to reduce the emission amount of CO _2.

Processing method of steelmaking slag of this invention was made in order to solve the aforementioned problem, feed upon carbonating CaO content present in the steelmaking slag, while applying mechanical agitation to the steelmaking slag, a CO ₂ containing gas This is a steelmaking slag treatment method in which carbonation reaction is carried out, wherein the steelmaking slag is mechanically stirred in a state of containing 10 to 40 mm of granular materials.

  Moreover, when performing carbonation of steelmaking slag while performing mechanical stirring using a stirring vessel, it is preferable that the space filling ratio η occupied by the slag is 0.03 to 0.15 with respect to the internal volume of the stirring vessel.

(%f-CaO)i：処理前のフリーライム濃度(質量%)
(%f-CaO)f：処理後の目標フリーライム濃度(質量%)
t：処理時間(min)
η：空間充填率(-)
D：容器内径(m)
ω：容器回転数(rpm)
M：水分(質量%) Moreover, mechanical stirring is performed using a stirring vessel, and the processing time can be predicted using [Formula 1] to [Formula 5].

(% f-CaO) i: Free lime concentration before treatment (mass%)
(% f-CaO) f: Target free lime concentration after treatment (mass%)
t: Processing time (min)
η: Space filling rate (-)
D: Container inner diameter (m)
ω: Container rotation speed (rpm)
M: moisture (mass%)

Q_目標：目標の生産性（t/h)
η：空間充填率(-)
D：容器内径(m)
L：容器長さ(m)
ω：容器回転数(rpm)
M：水分(質量%)
ρ：製鋼スラグの嵩密度(t/m³)
(%f-CaO)_i：処理前のフリーライム濃度(質量%)
(%f-CaO)_f：処理後の目標フリーライム濃度(質量%) Further, mechanical stirring is performed using a stirring vessel, and the inner diameter D, length L, and rotational speed ω of the vessel are set to [Equation 1] to [Equation 3] and [Equation 6] so that the desired productivity Q can be obtained. It can be made to select according to.

Q _Goal: The goal of productivity (t / h)
η: Space filling rate (-)
D: Container inner diameter (m)
L: Container length (m)
ω: Container rotation speed (rpm)
M: moisture (mass%)
ρ: Bulk density of steelmaking slag (t / m ³ )
(% f-CaO) _i : Free lime concentration before treatment (mass%)
(% f-CaO) _f : Target free lime concentration after treatment (mass%)

The above is due to the fact that the inventors have determined what limits the limits of conventional carbonation treatment methods in the course of research leading to the present invention.
That is, steelmaking slag was filled in a filling tank, and carbonation of free CaO in the slag was attempted through CO ₂ gas or a mixed gas of argon gas and CO _{2 in} the slag in a stationary state. In this case, the proportion of free water, H in the gas, such as at a high temperature of 800 ° C. to 700 ° C., a high pressure of about 9 atm, a water vapor saturation condition of 70-80 ° C., at a room temperature where water coexists, and so on. Experiments were conducted under various conditions of ₂ O partial pressure, pressure, and temperature.

As a result, although the free lime concentration decreased in the reaction at the beginning of the treatment, it was found that the reaction substantially stopped when the free lime concentration decreased to 1 to 2% under any experimental conditions. This phenomenon is the same even when the CO ₂ partial pressure is increased as in Patent Document 5 or when the reaction is performed at a high temperature of 300 ° C. or higher as disclosed in Patent Document 2. Also, from the observation of the microstructure of the slag after treatment, the reason is that the CaCO ₃ layer becomes a strong film when the outer surface of the free CaO particles present in the slag particles is converted to CaCO ₃ to a thickness of about 50 μm. It was found that this was to inhibit the diffusion of _{2 into} the particle.
This is because the reaction, such CaO is imagined from the fact that the molar volume of approximately 2-fold changes in CaCO _3, since the closed pores present in the slag particles, more, of CO ₂ slag particles It can be understood that diffusion into the inside or penetration of water in which CO ₃ ^2- ions are dissolved does not occur.

On the other hand, the inventors of the present application have conceived that if a strong mechanical stirring is applied to some extent, the CaCO ₃ film is broken or cracks are generated, so that diffusion of CO ₂ is maintained. And conducted experimental research. As a result, under a certain degree of mechanical agitation, the reaction does not stop in a short time, and the free lime concentration can reach a low concentration of 1% or less without causing cloudiness when immersed in seawater. I understand. Moreover, since it is such a phenomenon, it is not necessary to grind slag or perform extra pretreatment in order to increase the specific surface area of the reaction.

On the other hand, claim 9 of the above-mentioned Patent Document 3 describes that the slag particles are crushed in advance, and this is considered to generate a new surface and facilitate reaction. However, CaO + CO ₂ → CaCO ₃ reaction causes CaO to be about twice the volume, so no matter how much the new surface is exposed in advance, the above mechanism, that is, a CaCO ₃ layer is formed on the surface, which is dense. Therefore, the reaction is still stopped by preventing the diffusion of CO ₂ . Therefore, the elution pH remains high because several percent of free CaO always remains.

In contrast, in the present invention, by performing CO ₂ conversion simultaneously with mechanical stirring, the CaCO ₃ film is always destroyed or cracked in the film, so the reaction proceeds faster to a lower concentration. Yes, it is possible to reduce the free lime concentration of slag with high productivity, which is unprecedented.

That is, as the conventional knowledge, slag CO ₂ gas or the like is supplied attempt to carbonation of CaO in the slag in the way the film of CaCO ₃ layers also CaO carbonation reaction of quiescent insufficient Become. The present invention is to supply such CO ₂ gas while mechanically stirring the slag to be treated, not in a state where the slag to be treated is stationary, but to identify the optimum conditions for mechanical stirring. Thus, the conventional problems are solved all at once.

In general, when processing slag, the slag to be processed is performed in a stationary state in consideration of the ease of processing, etc., but the present invention is greatly different in its concept from moving the slag as mechanical agitation. When processing in a specific state, it is based on a very novel technical idea that not only mechanical stirring but also mechanical stirring under specific conditions.
That is, as will be described later, the present inventors have found that there is an optimum value for the space filling rate to be filled in the stirring vessel in order to maximize productivity. Furthermore, the effects of the filling rate, the inner diameter of the stirring vessel, the rotation speed, and the moisture on the reaction rate were quantified. As a result, the processing time required when using a certain stirring vessel can be predicted, and processing is not wasted. Alternatively, the container inner diameter, rotation speed, and length necessary to obtain a certain processing productivity can be selected, that is, the apparatus can be designed.

  In general, steelmaking slag is not composed of particles of a single size, but when used for road roadbed materials or the like, a standard particle size distribution is determined, and it is desirable to have a certain particle size distribution. On the other hand, according to this method, it is not necessary to process only those of 5 mm or less or 1 mm or less as shown in Patent Document 3. This is because in this method, mechanical stirring is performed in a state of containing 10 to 40 mm of particulate matter together with several millimeters of fine powder, and carbonation proceeds to the inside of particles of 10 mm or more, and free lime is reduced. is there. In the case of a slag containing a large amount of 10 mm or more, this facilitates the role of the ball of the ball mill, that is, the crushing action. On the other hand, when only small-diameter particles are included, it is preferable to intentionally include, for example, iron ball particles that are hard and have a certain mass. In the case of an iron ball, it is advantageous because magnetic separation can be performed later. If magnetically-granulated iron obtained in the magnetic separation process is used instead of the iron ball, it is not necessary to purchase a new one, and it is inexpensive and convenient.

Further, Patent Document 3, as a method of reducing exhaust carbon dioxide, CaO and / or Ca (OH) ₂ is brought into contact with exhaust gas containing CO ₂ into aggregates of solid particles comprising the, the CO ₂ in the exhaust gas solid Although a method of reducing the CO ₂ concentration in the exhaust gas by fixing it as CaCO _{3 to the} particles is disclosed, it is a filling tank type form in which the stationary slag is reacted with the CO ₂ -containing gas, so the reaction rate is There is a problem that it is small and productivity is low, and if the amount of CO ₂ emitted per unit time is large, such as in a steel plant, a large number of carbonation facilities are required to obtain the reduction effect. Is not realistic. On the other hand, since the reaction rate is high in the present invention, a large reduction effect can be obtained even with a small number of facilities.

  Furthermore, by treating slag with a wide particle size distribution as the object of processing, those with a large particle size are greatly affected by the impact energy that accompanies the drop applied to other particles as it falls in the rotating container, and the reaction rate is reduced. It has been found convenient to maintain. Furthermore, in the present invention, it has been found that it is desirable to include particles of 10 to 40 mm in the particles constituting the steelmaking slag. That is, if it is less than 10 mm, the impact energy accompanying the drop is small, and the effect is not remarkable. On the other hand, if it is larger than 40 mm, the slag after treatment exceeds the upper limit of the roadbed material standard, which is inconvenient. Therefore, the diameter of the granular material is in the range of 10 mm to 40 mm.

K：フリーライム低下反応速度の容量係数(1/min)
(%f-CaO)_i：処理前のフリーライム濃度(質量%)
(%f-CaO)_f’：処理後のフリーライム濃度(質量%)
t：処理時間(min) In addition, the inventors of the present application derived an equation that can predict the reaction rate as an empirical rule. According to this, it was found that the course of the initial free lime concentration shows a so-called primary reaction behavior that becomes a straight line when logarithmically plotted against time. This suggests that the reaction rate is limited by the collision process of the free lime particles with the other particles. The magnitude of the reaction rate is the slope of the logarithmic plot, that is, the K value of the following [Equation 7]. Clarified that it can be evaluated.

K: Capacity coefficient of free lime lowering reaction rate (1 / min)
(% f-CaO) _i : Free lime concentration before treatment (mass%)
(% f-CaO) _f ': Free lime concentration after treatment (mass%)
t: Processing time (min)

Furthermore, the inventors of the present application conduct experiments using reaction vessels of various sizes, and finally, [Expression 4] is established as a relational expression between the capacity coefficient K of the free lime reduction reaction rate and the processing conditions. I found.
[Equation 4]
K = 0.00215 (1-η) ^11.88 D ^0.56 ω ^1.04 M ^0.23
K: Capacity coefficient of free lime lowering reaction rate (1 / min)
η: Space filling rate (-)
D: Container inner diameter (m)
ω: Container rotation speed (rpm)
M: moisture (mass%)

  Further, the K value shown in [Equation 4] has a maximum K value within a range of η from 0.03 to 0.15 under certain conditions of D, ω, and M. That is, as shown in FIG. 2, the maximum productivity can be obtained with a given stirring device when η = 0.078. Actually, the upper limit of η is 0.15. Then, the decline in productivity is within 30%, and high productivity can be maintained. On the other hand, if the lower limit of η is 0.03, the decrease in productivity with respect to the maximum value will be 30%. However, as shown in FIG. 2, if η deviates slightly in this region, the productivity suddenly decreases. Therefore, it is reasonable to set it to 0.04 or higher.

Thus, since the relationship between the various conditions during stirring and the reaction rate was obtained, the free lime concentration of slag was reduced from a certain initial value to 1% or less of the target from the inner diameter, length, and rotation speed of the apparatus. Can be estimated. Thereby, the productivity of the processing apparatus can be estimated.
Furthermore, if this is used in reverse, as shown in the following [Equation 8], it is possible to determine the specifications such as the inner diameter, length and rotational speed of the apparatus for a certain required processing capacity, that is, design of the equipment. Is possible.

［数4］式から、処理時間tが、下記の［数5］式で求められる。
t=ln[(%f-CaO)_i/(%f-CaO)_f]/K
［数5］式に［数4］式を代入して整理すると、処理の生産性を表す［数10］の次式を得る。

On the other hand, the internal volume of the container is πD ² L / 4, and W is expressed by the formula [9] using the filling rate η and the bulk density ρ.

From the formula [4], the processing time t is obtained by the following formula [5].
t = ln [(% f-CaO) _i / (% f-CaO) _f ] / K
Substituting [Equation 4] into [Equation 5] and rearranging results in the following [Equation 10] representing the productivity of processing.

  As shown in FIG. 2, the [Equation 10] expression becomes maximum when η = 0.078. In addition, in actual production equipment, it is natural to aim for maximum productivity in order to maximize the effect of capital investment. From Fig. 2, in order to secure 70% or more of MAX productivity, As described in [0027], η = 0.03 to 0.15.

Furthermore, when this idea is expanded and the conditions of the continuous reactor are determined, the inner diameter D that satisfies the equation [6] for the required processing productivity Q _target and the free lime concentration before and after the processing is satisfied. The combination of the length L and the rotational speed ω is obtained. Also, η is preferably 0.03 to 0.15 for the above reason. Further, regarding M, 5 to 20% by mass may be secured. It is less than 5 wt%, the diffusion to the reaction site via a water CO _2, i.e. CO ₃ are for insufficient diffusion effect by ^2-ion, also this becomes the order dust becomes severe or less It is. On the other hand, if moisture exceeding 20% by mass is applied, the mass increases and extra stirring power is required.
Further, when the reaction time is long and the water content falls below this range, water vapor may be included in the supplied CO ₂ -containing gas in order to appropriately add or suppress evaporation.
The stirring vessel is not limited to a cylindrical shape having the same inner diameter, and may be a cone or a funnel shape. The vessel inner diameter D is calculated from the internal volume and length. The effective diameter may be used as D.

ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to stabilize the steelmaking slag with high productivity at low processing costs, that is, the slag that does not cause white turbidity even when immersed in seawater. In addition, CO ₂ emissions can be reduced.

FIG. 1 is a conceptual diagram of an example of equipment suitable for carrying out the present invention.
A container for mechanical stirring includes a rotating drum 1 and a stirring blade 2 inside, and is composed of an inlet for raw materials such as slag and a gas supply facility 3. The raw material slag is charged into the drum 1, the drum 1 is rotated, and processing is performed by supplying a CO ₂ -containing gas while applying mechanical stirring. After processing for a predetermined time, slag is discharged from the discharge hole.
Moreover, the processing method of this invention may be a continuous processing process of taking out continuously from a discharge hole, for example, supplying a raw material continuously from an inlet. To make the effect of mechanical stirring effective, a stirring blade 2 is installed. The number of stirring blades 2 may be as required.

A mixer truck can also be used as a container for mechanical stirring.
In this case, the steelmaking slag generated at the steel works is put into the rotating drum of the mixer truck, and the carbonation reaction is performed by mechanical stirring while supplying, for example, lime kiln exhaust gas. After that, the mixer truck can be used for direct use at the site. In addition, it is possible to carry out the carbonation reaction by mechanical stirring while supplying the CO ₂ -containing gas there after going straight to the site.

The desiliconization and phosphorus removal treatment of the gun was performed using a converter reactor. The slag composition and particle size distribution at this time are those in Table 1. This slag 3.2t was filled into a cylindrical stirring vessel, and with 9.6% by mass of water, stirring was applied at a rotation speed of 4 rpm, and the exhaust gas from the lime firing kettle generated in the steel works was 120 Nm ₃ from the charging hole. It was supplied at a flow rate of / h. The content concentration of CO ₂ was 14 to 26 mol%. After 8 hours, the free lime concentration was less than 1.0% by mass, and no white turbidity occurred even when poured into seawater.
On the other hand, when only 5 mm under of the same slag was used, the free lime reached value was 2.1% by mass under almost the same processing conditions (Comparative Example 1).

Hot metal desiliconization dephosphorization slag was charged into a concrete mixer truck and processed. The filling rate was 0.095, and after 4 hours of treatment, the initial free lime concentration of 8.1% by mass decreased to 0.88% by mass and below 1.0% by mass.
On the other hand, when the filling rate was 0.3 and excessive, the other conditions were the same, but decreased only to 6.22% by mass (Comparative Example 2).

The desiliconized and dephosphorized slag was processed under the conditions shown in Table 3. In this case, 2.3 t of slag having a free lime concentration of 4.08% by mass was treated. The exhaust gas from the calcining lime generated in the steel works was supplied at a flow rate of 120 Nm ³ / h. The content concentration of CO ₂ was 17 to 20 mol%. The free lime concentration after the treatment decreased to 0.95% by mass.

Continuous treatment was carried out under the conditions shown in Table 4. Using a cylindrical reactor having an inner diameter of 3.1 m and a length of 36 m, the sample was passed at a speed of 21 t / h. The combustion exhaust gas flowed 4000 Nm ³ / h into the reactor. The CO ₂ concentration in the gas was 18-27 mol%. The free lime concentration, which was 4.18% by mass at the entrance, decreased to 0.97% by mass.
On the other hand, in Comparative Example 4, the inner diameter was 2.1 m, and the other conditions were the same as in Example 4. However, the free lime concentration was reduced to 1.50% by mass, and the target was 1.0% by mass or less. Did not reach.

It is a general-view figure which shows a suitable apparatus for implementing this invention. It is a graph which shows the relationship between processing productivity and a filling rate. It is a graph which shows the cumulative particle size distribution of slag.

Explanation of symbols

1 Rotating drum 2 Stirring blade 3 Gas introduction pipe

Claims (4)

A method for treating steelmaking slag in which carbonation is carried out by supplying a CO ₂ -containing gas while giving mechanical stirring to the steelmaking slag when carbonating the CaO content present in the steelmaking slag. A method for treating steelmaking slag characterized by mechanically stirring in a state containing 10 to 40 mm of granular material.   The space filling factor η occupied by the slag is 0.03 to 0.15 with respect to the inner volume of the stirring vessel when performing carbonation treatment of the steelmaking slag while performing mechanical stirring using the stirring vessel. Of steelmaking slag. The processing method of the steelmaking slag of Claim 1 or 2 which performed mechanical stirring using the stirring container and predicted processing time using [Equation 1]-[Equation 5].

(% f-CaO) i: Free lime concentration before treatment (mass%)
(% f-CaO) f: Target free lime concentration after treatment (mass%)
t: Processing time (min)
η: Space filling rate (-)
D: Container inner diameter (m)
ω: Container rotation speed (rpm)
M: moisture (mass%) The inner diameter D, length L, and rotation speed ω of the container are selected according to [Equation 1] to [Equation 3] and [Equation 6] so that the desired productivity Q can be obtained by performing mechanical stirring using the stirring vessel. The method for processing steelmaking slag according to claim 1, 2, or 3.

Q _Goal: The goal of productivity (t / h)
η: Space filling rate (-)
D: Container inner diameter (m)
L: Container length (m)
ω: Container rotation speed (rpm)
M: moisture (mass%)
ρ: Bulk density of steelmaking slag (t / m ³ )
(% f-CaO) _i : Free lime concentration before treatment (mass%)
(% f-CaO) _f : Target free lime concentration after treatment (mass%)

Images