JP5262679B2 - Method for evaluating solidification characteristics of steel slag and method for evaluating anti-caking agent of steel slag - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for evaluating solidification properties of steel slag even in one test piece and in one test accurately with sufficient repeatability and almost no dispersion, and a method for evaluating solidification properties with sufficient repeatability even when adding an anti-consolidating agent and also the performance of the anti-consolidating agent. <P>SOLUTION: In the method for evaluating the solidification properties of steel slag, a steel slag molding molded using the steel slag to be evaluated is used as a sample, and a propagation time of elastic wave propagated between two positions in the sample is continuously measured to evaluate the solidification properties of the steel slag from changes with the lapse of the propagation time. Further, the anti-consolidating performance of the anti-consolidating agent is evaluated from the evaluated result of the solidification properties of the steel slag in the steel slag molding to which the anti-consolidating agent is added. The solidification properties and the effect of the anti-consolidating agent in optional conditions are estimated using a parameter indicating the solidification properties of the slag obtained from the evaluated result, and a parameter indicating the anti-consolidating performance. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a method for evaluating solidification characteristics of a steel slag having a property of solidifying in a moisture environment, and a method for evaluating an anti-caking agent for steel slag. In particular, the present invention relates to a method for quickly and accurately evaluating the solidification characteristics of blast furnace granulated slag and a method for evaluating an anti-caking agent for blast furnace granulated slag.

  Steel slag has the property of solidifying in an environment where moisture exists. The degree of solidification varies depending on the type of slag and the environment. This property is preferable when slag is used as a cement raw material or concrete aggregate, but when it is solidified before being used as a raw material or aggregate, or when slag is treated as a granular material such as sand or gravel. It is not preferable because it forms a lump. Therefore, it is necessary to control the solidification characteristics according to the application.

  Steel slag mainly includes blast furnace slag and steelmaking slag. Steelmaking slag is often used with a relatively large particle size, and solidification becomes a problem, and although there are relatively few applications that actively use its own solidification characteristics, it solidifies in the long term in an underwater environment. Sometimes.

  On the other hand, blast furnace slag, especially granulated blast furnace slag, is used as a raw material for cement by making use of its latent hydraulic properties, and its use as a fine aggregate for concrete is also expanding. However, due to the latent hydraulic properties, there is a problem of solidifying during the storage period until it is used. For this reason, many techniques for preventing caking have been proposed.

  As described above, in order to evaluate the solidification characteristics of steel slag that has essentially solidified properties and to determine the effect of technology to prevent solidification or consolidation, the timing of solidification and the degree of solidification Must be evaluated accurately.

  In the case of granulated blast furnace slag, the method of directly evaluating the progress of consolidation of slag loaded in the field (field test) is, for example, the time-dependent change in penetration resistance when a rod is pushed into a pile loaded with slag. There are known a method of measuring the electric field and a method of monitoring electric capacity and electric conduction by embedding an electrode in a slag mountain. Furthermore, slag granules may be sampled from the piled up over time, and changes over time such as specific surface area, water absorption rate, density, performance rate, etc. of the sampled slag granules may be measured.

  However, such a field test is often performed as a final confirmation test because there are many influencing factors such as weather, and the evaluation of solidification characteristics is generally performed by a test under a certain condition in a room. There are many. As a method of evaluating the consolidation of granulated blast furnace slag indoors, slag granules solidify in a lump, so the slag after granulation is filled into a container as it is, cured at a constant temperature, and consolidated. A method for evaluating the strength of the sheet is generally used.

  In addition, as a method for evaluating the solidification characteristics in a room used in the conventional anti-caking technique, for example, in Patent Document 1, a cylindrical container is filled with a blast furnace slag fine aggregate having a particle diameter of less than 5 mm, and is kept at a constant temperature. Cured, removed after a suitable period of time, measured for particle size, and evaluated the degree of consolidation from the production rate of particle size of 5 mm or more. In Patent Document 2, blast furnace slag fine aggregate was put on the bag. After sealing and isothermal curing, the specific surface area is measured after an appropriate period of time, and the degree of consolidation is evaluated from the change in the specific surface area.

Since these methods for evaluating solidification characteristics in a room described in the patent document are generally performed under accelerated conditions, that is, test conditions that shorten the time until solidification, the time until solidification does not match the direct evaluation method in the field test. The comparative evaluation test was stopped.
Japanese Patent Laid-Open No. 2003-160364 JP 2005-82427 A

  By the way, since the conventional indoor evaluation methods as seen in the above-mentioned patent documents have constant conditions, the reproducibility of the evaluation results is better than the field test, but the solidification characteristics are determined from the measured values of strength and particle size. In order to evaluate, the variation of the evaluation result is large, and in order to further increase the reliability, it is necessary to increase the amount of samples and the number of measurements. Furthermore, in the case of an unknown steel slag that has not been tested, or a steel slag that is difficult to predict the progress of solidification due to the addition of a new anti-caking agent, it may be necessary to repeat trial and error. There was a problem that several samples were required.

  Therefore, the present invention has an object to provide a method for evaluating solidification characteristics of steel slag that can evaluate the solidification characteristics even with a single test body, and can evaluate the solidification characteristics with little reproducibility even in a single test. To do. It is another object of the present invention to provide a method capable of evaluating the solidification characteristics with good reproducibility even when an anti-caking agent is added, and also evaluating the performance of the anti-caking agent.

In order to solve the above-described problems, the present invention provides the following methods for evaluating solidification characteristics of steel slag and methods for evaluating an anti-caking agent for steel slag.
(1) Using a steel slag compact formed using the steel slag to be evaluated as a sample, continuously measuring the propagation time of the elastic wave propagating between two positions in the sample, It is a method for evaluating the solidification characteristics of the steel slag from the change, and the propagation time of the elastic wave is measured under the conditions of two or more kinds of test temperatures T (T1, T2,. T1, T2, ...) are continuously measured until the propagation time converges to the same constant value, and the initial propagation time (tmax) of the steel slag compact in the time-dependent change of the measured propagation time and the A predetermined propagation time (tx) is arbitrarily determined between the convergence propagation time (tmin) when converged to a constant value, and each test temperature T (T1, T1, T2) until the predetermined propagation time (tx) is reached. The curing time at T2, ...) reaches this predetermined propagation time (tx) Calculated as the solid sintering time d ₀ to the test temperature T (T1, T2, ......) relationship to the following equation and the consolidation time d ₀ (1) (where, in the formula, R is a gas constant .) To obtain constants A and E, and reach a predetermined propagation time (tx) at the environmental temperature Tx at the time of solidification characteristic evaluation from the formula (1) in which the values of the obtained constants A and E are introduced. caking time d ₀ estimated up, evaluating solidification characteristics of steel slag from the estimated consolidated time d ₀ to the ambient temperature Tx of the solidification characteristics evaluation reaches a predetermined propagation time (tx) Of solidification characteristics of steel slag characterized by

  (2) The method for evaluating solidification characteristics of steel slag according to (1), wherein an anti-caking agent is added to the steel slag compact.

  (3) The method for evaluating solidification characteristics of steel slag according to (1) or (2), wherein the steel slag is blast furnace granulated slag.

  (4) The sample is a cylindrical steel slag molded body having two planes, and the propagation time of the elastic wave from the time when the elastic wave is input from one plane of the molded body to the other plane The method for evaluating solidification characteristics of steel slag as set forth in any one of (1) to (3), wherein the solidification characteristics of the steel slag are evaluated from changes over time in the propagation time. .

( 5 ) The predetermined propagation time (tx) defined between the initial propagation time (tmax) and the convergence propagation time (tmin) of the steel slag compact is equal to the initial propagation time (tmax) and the convergence time. The method for evaluating solidification characteristics of steel slag according to any one of (1) to (4), characterized in that it is an intermediate value (t ₅₀ ) in a logarithmic value with respect to propagation time (tmin).

( 6 ) An anti-caking agent evaluation method using the method for evaluating solidification characteristics of steel slag according to any one of (2) to ( 5 ), wherein the anti-caking agent is added. wherein the temporal change of the propagation time in the slag formed body to evaluate the solidification characteristics of the steel slag, a method of assessing the anti-caking performance of the anti-caking agent from the solidified characterization results of this steel slag, the steel As samples of the slag molded body, samples with no anti-caking additive added (0) and two or more samples with different caking inhibitor addition amounts m (m1, m2,...) Were used. The elastic wave propagation time is continuously measured until the propagation time converges to the same constant value, and the initial propagation time (tmax) of the steel slag formed body in the time-dependent change of the measured propagation time and the constant value Between convergence time (tmin) when converged to In, arbitrarily determine a predetermined propagation time (tx), determine the curing time in each sample until reaching the predetermined propagation time (tx) as the consolidation time to reach this predetermined propagation time (tx), anti-caking agents without the addition (0) caking time of the sample and d ₀ of, also, anti-caking agent addition amount m (m1, m @ 2, ......) caking time each sample d _r of (m1) , d _r (m @ 2), and ..., the caking time d ₀ and the anti-caking agent addition amount m and consolidation time _{d r (m1), d r} (m2), the relationship between ...... follows Applying to the formula (2), the constants a and n are obtained, and the predetermined propagation at the anti-caking additive addition amount mx at the time of solidification characteristic evaluation from the formula (2) in which the values of the obtained constants a and n are introduced. estimating caking time d _r to reach time (tx), the solidification time d _r to the anticaking agent amount mx during the solidification characterization reaches a predetermined propagation time (tx) An evaluation method for an anti-caking agent for steel slag, characterized by evaluating solidification characteristics of the steel slag.

( 7 ) The predetermined propagation time (tx) defined between the initial propagation time (tmax) and the convergence propagation time (tmin) is the initial propagation time (tmax) and the convergence propagation time (tmin). The method for evaluating an anti-caking agent for steel slag as described in ( 6 ), which is an intermediate value (t ₅₀ ) in the logarithmic value of.

  According to the present invention, it is possible to quickly and accurately evaluate the solidification characteristics of steel slag. In addition, the performance evaluation of the anti-caking agent can be performed quickly and accurately, and can be used for appropriate solidification control measures for steel slag.

  In the method for evaluating solidification characteristics of steel slag according to the present invention, a steel slag molded body formed using the steel slag to be evaluated is used as a sample, and the propagation of elastic waves propagating between two positions in this steel slag molded sample. The time is continuously measured, and the solidification characteristics of the steel slag are evaluated by the change over time of the measured value. Here, the two positions in the sample for measuring the propagation time of the elastic wave are from an arbitrary position to another arbitrary position in the propagation path of the elastic wave propagating from one of the steel slag compacts to the other. However, it is preferable that two positions from the position of the surface of the molded body where the elastic wave is input into the steel slag molded body to another position on the surface of the molded body that receives the elastic wave are preferable. One position is recommended. These two positions may be points or planes.

  A steel slag compact as a sample used in the method for evaluating solidification characteristics of steel slag according to the present invention is formed by compression-molding steel slag containing moisture. The sample for evaluation only needs to be compression-molded with powder or particles, and the shape is maintained, and the particle size of the powder or particles, the amount of water added as necessary for molding, and the compression load are also particularly limited. It is not a thing.

  However, in order to relatively compare the solidification characteristics of various slags, it is preferable that the steel slag compacts are molded under uniform molding conditions. As for the particle size, in the case of blast furnace granulated slag, the particle size of slag fine powder for cement raw material of JIS A6206 is easy to handle, and the reproducibility of test results is particularly good. In the case of other slags, if they are evaluated by pulverizing to this particle size, a relative comparison becomes easy. If it is about several mm or less, it can be used as it is. In the case of blast furnace granulated slag, since it is a particle of several mm or less at the time of manufacture, it can be directly squeezed into a container and used as a sample.

  Although the embodiment about the case where powder slag is used is described below, the case of granular slag can be basically applied by the same method.

  Regarding the water content, for example, in the case of blast furnace granulated slag, the water content when this blast furnace granulated slag is stacked in the field is about 5 to 10% by mass. It is preferable to use about%. However, for relative comparison, it is more desirable to unify the test conditions, and it is preferably about 10% by mass from the viewpoint of easy handling and molding of the sample. This is because when the particle size is about the same as slag fine powder for cement raw material of JIS A6206, it is easy to handle when the water content is 10% by mass.

  The compressive load may be any load as long as the sample does not collapse. When 10% by mass of water is added to the JIS blast furnace slag fine powder, it is easy to mold when about 30 MPa is used. was gotten. However, it is desirable to unify the test conditions for relative comparison. If the pressure is 15 MPa or less, the sample is easily broken by the contact pressure at the time of measurement, so a certain molding pressure is required.

  As for the sample shape, it is only necessary to extract elastic waves propagating through the sample at positions separated from each other by a predetermined distance, but it is preferable that the measurement is easy, or a contact point that can input and output elastic waves to the sample or There should be a contact surface, and there are no restrictions on the other shapes. In the case of uniaxial compression molding, such as molding into a cylindrical shape, since parallel planes are formed, it is most preferable because elastic waves can be input from one plane and received from the other plane, making measurement easier. However, even a sample formed into a spherical shape can be measured if there are two contact points. When the JIS blast furnace slag fine powder is used, the length through which the elastic wave passes, that is, the thickness of the sample is preferably about 20 mm in consideration of the elastic modulus and density of the slag. Further, the cross-sectional dimension of the sample is easy to handle when it is about φ20 mm when the shape of the molded body is cylindrical.

  In the present invention, an elastic wave is input from an arbitrary position (one point or one surface) to a compression-molded sample, and the propagation time of the elastic wave reaching a different arbitrary position (one point or one surface) is measured. However, it is preferable to measure the propagation time of elastic waves between two points or two surfaces that are easy to measure. For example, in a cylindrical molded body, an elastic wave is input from one flat surface and the other. It is desirable to measure the propagation time between the two surfaces by receiving the elastic wave on the flat surface.

  Here, an example of the solidification characteristic evaluation apparatus which implements the measuring method using the uniaxial compression molding which has a parallel plane as a sample is shown in FIG. The elastic wave transmitting element 1 and the elastic wave receiving element 2 are sufficiently brought into contact with the molded end surface of the sample 3 so that the elastic wave can be easily transmitted. Since the contact pressure at this time affects the propagation time, it is necessary to keep it constant. If the contact pressure is low, the elastic wave is difficult to transmit and the propagation time varies depending on the contact state, but if the pressure exceeds a certain pressure, the propagation time becomes stable. What is necessary is just to measure with the contact pressure of the grade which the sample does not collapse.

  The elastic wave transmission / reception elements 1 and 2 may be transmitted by the elastic wave transmission / reception elements 1 and 2, and the received elastic wave may propagate through the slag sample 3, and the material and performance are not particularly limited. Examples of versatile and easy to handle include lead zirconate titanate piezoelectric elements.

  The frequency that can be used is any elastic wave that propagates with less attenuation in the sample 3. For example, when JIS blast furnace slag fine powder is used, a piezoelectric element having good sensitivity at a resonance frequency of 160 to 260 kHz may be used.

  The elastic wave excited by the electric signal from the pulsar 4 is output from the elastic wave transmitting element 1 and input to the sample 3. The elastic wave propagating through the sample 3 is received by the elastic wave receiving element 2 and converted again into an electric signal. The electric signal is amplified by the signal amplifier 5, and the amplified electric signal is used as a measurement electric signal for the oscilloscope 6. To enter. On the other hand, an electrical signal is transmitted from the pulsar 4 to the elastic wave transmitting element 1 as described above, and at the same time, the electrical signal from the pulsar 4 is input to the oscilloscope 6 as a trigger signal. The oscilloscope 6 measures the arrival time difference between the trigger signal and the measurement electric signal that has reached through the sample 3.

  In the present invention, it is important that the propagation time of the elastic wave in the sample can be measured. As the measurement method, an elastic wave element (piezoelectric element) capable of mutually converting pressure and voltage is used and measurement is performed by measuring an electric signal. In this case, the arrival time difference of the electric signal is important. The oscilloscope can perform waveform analysis and the like, but any device can be used as long as it can measure the arrival time difference of electrical signals. The pulsar 4 preferably has a trigger function. However, if the trigger signal can be synchronized with the elastic wave excitation electric signal to the elastic wave transmitting element 1, a trigger device is used separately from the pulsar 4. You can also.

  The elastic wave transmitted through the sample 3 generally includes a longitudinal wave and a transverse wave. However, in the present invention, it is difficult to input a transverse wave, and therefore a longitudinal wave is recommended. In the powder compact before being solidified, there is a considerable amount of elastic wave attenuation, but the longitudinal wave has less attenuation and is easier to detect and measure. On the other hand, the elastic wave transmitting element 1 and the elastic wave receiving element 2 are brought into direct contact to measure the signal delay time in the measuring device. The propagation time of the elastic wave in the sample 3 is obtained from the difference between the arrival time when the sample 3 is used and the signal delay time in the device. If the signal delay time in the measuring instrument is negligibly small compared to the propagation time in the sample, it is possible to make a relative comparison only with the propagation time in the sample without strictly obtaining the time difference.

  In the present invention, the timely propagation time is continuously measured after the sample is formed, and the solidified state is grasped from the change over time. Immediately after the compression molding, the slag particles in the sample are only in contact with each other, and the elastic wave has a large delay when passing through the contact point between the slag particles, and the propagation time in the sample becomes long.

  Solidification of slag is considered to be a phenomenon in which, after calcium, silicate ions, etc. are eluted from slag, they are again deposited between slag particles by a hydration reaction, and the slag particles gradually bond to each other. In the initial stage after molding, the slag particles are still weakly bonded due to solidification, and almost no change from the propagation time immediately after molding is observed. Thereafter, as the solidification progresses and the bond between the slag grains becomes stronger, the propagation time begins to shorten. This time can be used as an index for the start of solidification.

  However, the solidification start index is not limited to this propagation time lowering start point, and an arbitrary propagation time is determined below the propagation time at the time of compression molding, and the elapsed time until the propagation time is decreased is an index. It is also possible to make a relative evaluation of the solidification characteristics.

  In this way, by continuously measuring the propagation time of the elastic wave in the steel slag molded body, it is possible to grasp the change with time of the solidified state, and evaluate the solidification characteristics by using, for example, the solidification start time as an index. be able to.

  The measurement of the propagation time of the elastic wave in the present invention is reliable without being overlooked if it is started immediately after molding, but it is not necessary to start immediately after molding if at least a change in propagation time can be measured.

  In the method of the present invention, the effect of the temperature and the anti-caking agent on the solidification characteristics can be accurately evaluated, and these influences appear in the time when the propagation time starts to decrease and the rate of change of the propagation time thereafter, so the measurement starts. When it cannot be predicted at the time, it is preferable to start measurement immediately after molding.

  The present invention is particularly effective when applied to blast furnace granulated slag among steel slags. Blast furnace granulated slag is most concerned with solidification and needs the most evaluation of solidification characteristics.

  Furthermore, as a technique for preventing caking of blast furnace granulated slag, a method of adding an anti-caking agent is widely used, but in the present invention, even blast furnace granulated slag to which an anti-caking agent has been added is used. Similarly, the solidification characteristics can be evaluated.

  Furthermore, the performance of the anti-caking agent can be accurately evaluated according to the present invention. The method for evaluating the performance of the anti-caking agent is the same as the method for evaluating the solidification characteristics of steel slag described above, except that an aqueous solution of the anti-caking agent is added to the steel slag before forming and sufficiently mixed. Decide an arbitrary propagation time, and use the elapsed time until the propagation time is reduced as an index to prevent solidification, and evaluate that the longer the elapsed time until the propagation time decreases, the higher the anti-caking effect. Can do.

  In the present invention, in order to qualitatively evaluate the solidification characteristics, it is sufficient to use the time when the propagation time suddenly decreases as described above as an index of the solidification characteristics. However, the solidification characteristics can be quantitatively evaluated by the following method.

  The inventor examined in detail the influence of temperature on solidification characteristics using fine powder of granulated blast furnace slag, and obtained the relationship shown in the schematic diagram of FIG. Then, when the measured values of the propagation times at the different temperatures T1 and T2 with respect to the test temperature T are smoothly connected, an inverted S-shaped curve in FIG. 3 is obtained and the solidification behavior is different.

Here, it is clear that the initial propagation time of the sample molded under the same conditions is almost equal since it is not yet affected by the temperature change and the presence or absence of the anti-caking agent. This initial propagation time was defined as tmax. In addition, in the experiments by the inventors, it has been found that the propagation time of the sample cured for a long time after molding converges to a substantially constant value regardless of the history of changes in temperature and the presence or absence of an anti-caking agent. This convergence time is defined as tmin. Then, the intermediate value in the logarithmic value of the above tmax and tmin is defined as t _50, and further, the curing time until the propagation time reaches t ₅₀ is used as a solidification characteristic index 50% consolidation time d ₀ (day ).

In FIG. 3, the 50% consolidation time d ₀ is different at temperatures T 1 and T 2, and d ₀ (T 1) and d ₀ (T 2), respectively.
Here, the inventor obtained the tangent at the point of the 50% consolidation time d ₀ with respect to the inverted S-shaped solidification curve of FIG. 3, and the tangent to each temperature T1, T2 is on the propagation time axis. It was discovered that they would meet at The propagation time at this intersection was defined as t ₀ . As a result, the relationship of the following formula (1) was obtained for the 50% consolidation time d ₀ and the temperature T.

Where A is a constant (1 / day), E is the activation energy (J / mol) related to the solidification reaction, T is the test temperature (K), and R is the gas constant. 314 J / mol / K.
In this relational expression (1), if A and E which are solidification characteristic values of slag are experimentally obtained in advance, by using the expression (1), 50% at an arbitrary environmental temperature Tx at the time of solidification characteristic evaluation. The consolidation time d ₀ can be estimated.

  Although the above method can be used for estimation under a constant temperature environment as in a laboratory experiment, the temperature varies in a field where blast furnace granulated slag is actually stored. In the present invention, estimation in an environment with temperature fluctuation is performed as follows. The right side of the following formula (1-2) obtained by transforming the formula (1) is equal to the reciprocal of the solidification characteristic value A of the blast furnace granulated slag, and is a constant value that includes a function of temperature but is not related to temperature. . Therefore, when temperature variation is taken into consideration, the temperature T is considered as a function of time T (t) as shown in Expression (1-3).

Here, t in the formula (1-3) means a curing time, dt is a differential display thereof, and is distinguished from the propagation time t and the meaning d of the consolidation time. That is, it means that exp (-E / RT) is integrated in the range of curing time t = ₀ to d0. This integrated value was defined as the integrated temperature. Then, using E obtained in advance, for example, when T (t) is the temperature change and the integrated temperature up to an arbitrary time t is determined, the integrated temperature is the reciprocal of the solidification characteristic value A of the blast furnace granulated slag. Is estimated to be 50% consolidation time d _{0 of the} granulated blast furnace slag in the environment of temperature T (t).

The temperature T calculated by applying the 50% setting time d ₀ obtained by the above method to the equation (1-2) is the solidification state when cured to d _{0 in the} environment of temperature fluctuation T (t). It can be considered as a constant curing temperature that is equivalent.

Furthermore, the inventor also examined in detail the relationship between the amount of anti-caking agent added and the caking delay time.
Even when an anti-caking agent is added, as shown in the schematic diagram of FIG. 4, the solidification behavior becomes an inverted S-shaped curve, and different anti-caking agent addition amounts m (m1, m2,...) It was found that the solidification behavior was different. In the same concept as above, a 50% consolidation time upon addition of anti-caking agent was defined as d _r.
4, unlike anti-caking agent addition amount m1, m2 50% consolidation time d _r, d _r (m1) each, respectively, was d _r (m2).

The inventor used 50% caking time d ₀ blast furnace granulated slag as a caking inhibitor, using sodium gluconate as a caking agent, and adding 50% to the mass m (mass%) of the caking inhibitor added to the unit slag mass. It was to investigate the relationship between the consolidation time d _r. When the temperature was constant, the slope of the tangent line hardly changed and the tangent intercept t ₀ was different. That is, it was found that the tangent moves in the curing time axis direction along with the added amount. As a result of further intensive investigation including temperature dependence, the relationship of the following formula (2) was found.

Here, a and n were considered to be constants depending on the performance of the anti-caking agent. Therefore, by experimentally determining a and n, which are indicators of the performance of the anti-caking agent, the anti-caking agent is added to the blast furnace granulated slag having a 50% caking time d ₀ at the time of solidification characteristics evaluation. 50% consolidation time d _r when added at a ratio (mass%), so that can be estimated by the formula (2).

Prediction of the setting time in an environment with temperature fluctuations of the slag to which the anti-caking agent is added is also possible by the equation (2). Although a and n indicating the performance of the anti-caking agent had almost no temperature dependence, the 50% caking time d ₀ of the granulated blast furnace slag depends on the temperature. If d ₀ taking into account temperature fluctuations by the above method is predicted by the formula (1-3), 50% consolidation time in an environment with temperature fluctuations when m (mass%) anti-caking agent is added. d _r can be estimated by applying this d ₀ to equation (2).

In the present invention, in order to evaluate the solidification characteristics more quantitatively, as an index of the solidified property, it is preferable to use a 50% consolidation time d ₀ or d _r as defined above. In the time-dependent change in the propagation time measured by the method according to the present invention, the period with the largest change is the initial propagation time tmax with no initial change and the convergence propagation time tmin when no change is recognized in the long term. between, in the middle of the time expressed in logarithmic value, because most small error when determining the consolidation time d _0, d _r. However, it is also possible to use a curing time until a propagation time arbitrarily determined between tmax and tmin is reached. At this time, when obtaining the constants of equations (1) and (2) and estimating the consolidation time therefrom, it is necessary to consistently use the same propagation time that is arbitrarily determined between tmax and tmin.

[ Reference Examples 1-8 and Comparative Examples 1-5]
Table 1 shows the test conditions and results of the reference example of the present invention, and Table 2 shows the test conditions and results of the comparative example. The steel slag used for the reference examples is three types of blast furnace granulated slag and steelmaking slag with different vitrification rates due to differences in production methods. The vitrification rates of the granulated blast furnace slags 1, 2, and 3 were 98%, 72%, and 97%, respectively.

A sample of a reference example was prepared by the following method. First, the dried steel slag was pulverized to a maximum particle size of 0.1 mm or less by a vibration mill, and 1 ml of pure water was added to 10 g of the obtained powder to be well adapted. Next, the hydrous powder was filled into a cylindrical mold having a diameter of 20 mm and compression-molded with a load of 1000 kg (31 MPa). The obtained steel slag compact had a diameter of 20 mm and a thickness of about 18.7 mm having a circular parallel plane. The steel slag compact was sealed with a plastic bag so as not to dry, and then cured at about 20 ° C. to prepare a sample.

  The obtained sample was set in the solidification characteristic evaluation apparatus shown in FIG. 1 using the circular parallel plane as a contact surface, and the propagation time was measured once a day continuously under the condition of a contact pressure of 0.15 MPa.

All the slags used in the reference examples of the present invention were pulverized for the same time using the same vibration mill. In addition, since the signal delay time in the measuring instrument used was about 1/1000 of the propagation time in the sample, relative evaluation was performed using the propagation time in the sample as it is. Samples having the same curing temperature conditions were cured together in the same curing tank.

FIG. 2 shows an example of change over time in propagation time measured in Reference Example 1 and Reference Example 4 of the present invention.
The legendary blast furnace granulated slag + anti-caking agent is a sample prepared by adding an aqueous solution containing an anti-caking agent to blast furnace granulated slag powder. The anti-caking agent used is sodium gluconate.

In the case of granulated blast furnace slag, it is confirmed that the propagation time has suddenly shortened after about 5 days, and in the case of granulated blast furnace slag + anti-caking agent after about 9 days. did. The rapid change time was regarded as the solidification start time, and the solidification characteristics of the samples were compared. Table 1 of the reference example describes the solidification start time according to the above definition. The compressive strength was obtained by measuring the maximum load when a compressive strength test apparatus was used to compress the sample after propagation time measurement by applying a compressive force perpendicular to the parallel plane.

In Reference Examples 1 to 3, the difference in solidification characteristics of blast furnace granulated slag with different production conditions was clearly shown by the difference in solidification start time. In Reference Example 1, since N = 3 measurements were almost the same result, evaluation was performed with the result of N = 1 in other Reference Examples.

In Reference Examples 4 and 5, anti-caking agents were added to the blast furnace granulated slag 1 in proportions of 0.0025% and 0.005%, respectively. The anti-caking agent used is sodium gluconate. By comparing with the reference example 1 using the same granulated blast furnace slag 1, the relationship between the addition amount of the anti-caking agent and the anti-caking effect could be clarified.

Reference Example 6 was an example in which the solidification characteristics of steelmaking slag alone were evaluated, and it was found that it solidifies more rapidly than blast furnace granulated slag.

Reference Example 7 is an example in which 10% of steelmaking slag was added to the blast furnace granulated slag 1, and it can be seen that solidification of the blast furnace granulated slag was accelerated by the steelmaking slag.

Reference Example 8 is an example in which 0.005% sodium polyacrylate was added as an anti-caking agent to the granulated blast furnace slag 1, and the caking start time was compared with that in Reference Example 5 to cause caking. The performance difference of the inhibitor could be clarified.

  Comparative Example 1 is a blast furnace granulated slag 1 having a particle size of 5 mm or less, which was evaluated for solidification characteristics by a method according to Patent Document 1. Curing at 40 ° C. began to produce a lump of 5 mm or more. It is an example which made the curing time of time the solidification start time. N = 3 test was conducted, but the solidification start time varied about 4 days.

  In Comparative Example 2, solidification characteristics were evaluated by using a blast furnace granulated slag 3 having a particle size of 5 mm or less according to a method according to Patent Document 1, and curing at 40 ° C. started to produce a lump of 5 mm or more. It is an example which made the curing time of time the solidification start time. As in Comparative Example 1, an N = 3 test was performed, but the solidification start time varied by about 4 days.

Since the curing temperature of the above comparative example does not use powder, it was set to a higher temperature than the reference example in order to accelerate solidification. Therefore, it is not possible to evaluate the solidification start time compared directly with the case of the embodiment, the evaluation method of the traditional has a large variation.

Comparative Example 3 and Comparative Example 4 were performed in parallel with Reference Example 1. A number of samples having the same conditions were prepared, one of which was used exclusively for the measurement of the propagation time in Reference Example 1, and the remaining samples were measured for the propagation time and at the same time, one sample per day, first as Comparative Example 4. The compressive strength was measured, and then the crushed sample as Comparative Example 3 was dried at 110 ° C., and the specific surface area was measured according to the method of Patent Document 2.

  Comparative Example 3 is an example in which the time at which a large change began in the specific surface area was set as the solidification start time. Although the variation was small, the change in the specific surface area at the start of solidification was small, and as a result, the solidification start time was evaluated to be longer.

Comparative Example 4 is an example in which the time at which a large change in the compressive strength began occurs was set as the solidification start time. As for the solidification start time, the same result as in Reference Example 1 was obtained. However, in order to destroy the sample for each test, a large number of samples were required so that the test could be performed until the solidification start time or longer.

Comparative Example 5 is an example in which an anti-caking agent was added and the same evaluation as Comparative Example 4 was performed. Although the same results as Reference Example 4 were obtained, many samples were required as in Comparative Example 4.

  In each of Comparative Examples 1 to 5, since the sample was destroyed every test, it was necessary to prepare a large number of samples so that the test could be performed until the solidification start time or longer.

From the results of Reference Examples and Comparative Examples, it can also evaluate the solidification characteristics by a single specimen, and it was found that variations in a single test can evaluate the little good reproducibility solidification characteristics. Further, it was found that the solidification characteristics can be evaluated with good reproducibility even when the anti-caking agent is added, and the effect of the anti-caking agent can be evaluated accurately and very efficiently.

[Example 9]
Next, Example 9 is an example of a solidification characteristic evaluation method in which the consolidation time is estimated using the above-described equation (1).
In Example 9, blast furnace granulated slag 4 manufactured under the same conditions as blast furnace granulated slag 1 (vitrification rate: 98%, maximum particle size: 0.1 mm, and addition amount of anti-caking agent: 0) %) And three samples were prepared in the same manner as in Reference Example 1. The curing temperature was fixed at 22.1 ° C., 26.3 ° C., and 30.5 ° C., respectively, and the change over time in the propagation time was measured.
The obtained results are shown in FIG.

From the results shown in FIG. 5, the initial propagation time tmax = 36 and the convergence propagation time tmin = 9, and a predetermined propagation time (tx) as an intermediate value in the logarithmic values of these tmax and tmin ( Table 3 shows the 50% setting time d ₀ obtained by employing t ₅₀ ).

The results of Table 3 were applied to formula (1), and values of A = 2.6 × 10 ¹⁵ (1 / day) and E = 92 kJ / mol were obtained. The consolidation time at other temperatures of the granulated blast furnace slag 4 can be estimated from equation (1) using the values of A and E. For example, the 50% consolidation time at 25 ° C. is estimated to be about 5.4 days. It was done.

[Example 10]
Example 10 is an example in which the consolidation time is estimated using the above-described equation (1), as in Example 9. In Example 9, the curing time until reaching the middle between tmax and tmin, that is, a predetermined value is used. In this example, the 50% setting time d ₀ obtained by adopting the intermediate value (t ₅₀ ) in the logarithmic value of tmax and tmin as the propagation time (tx) of the sample was used as an indicator of the solidification characteristics. 10, the curing time from tmax to tmin of 20%, that is, ln t ₂₀ = (0.8 × ln tmax + 0.2 × ln tmin) was considered as 20% consolidation time d ₀ .
Table 4 shows the results of the 20% consolidation time d ₀ obtained from the analysis shown in FIG.

The results of Table 4 were applied to equation (1), and values of A = 7 × 10 ¹⁵ (1 / day) and E = 93 kJ / mol were obtained. The activation energy E was almost the same value as in Example 9. The other temperature of the blast furnace granulated slag 4, for example, a 20% consolidation time at 25 ° C. was estimated to be about 3 days from the formula (1) in which the values of A and E were introduced.

[Example 11]
Example 11 is an example of an evaluation method for an anti-caking agent that estimates the caking time when the anti-caking agent is added using the above-described formula (2).
Blast furnace granulated slag 4 manufactured under the same conditions as granulated blast furnace slag 1 (vitrification rate: 98%, maximum particle size: 0.1 mm), sodium gluconate (Na gluconate) as an anti-caking agent Was added at a ratio of 0.0025 mass%, 0.005 mass%, 0.0075 mass%, and 0.01 mass%, and a sample was prepared in the same manner as in Reference Example 4 or 5. The time course of propagation time was measured at a curing temperature of 22.1 ° C.
The obtained results are shown in FIG.

From the results of FIG. 7, the initial propagation time tmax = 36 and the convergence propagation time tmin = 9, and an arbitrarily determined predetermined propagation time (tx) is an intermediate value in the logarithmic value of these tmax and tmin ( t ₅₀₎ shown in Table 5 50% consolidation time d _r calculated adopted.

When the d _r when the Na Gluconate amount of 0% to apply the formula (2) as d _0, the value of a = 758, n = 0.74 is obtained. When an indication of the performance of these anti-caking agent is applied to the equation (2), for example, the caking times of granulated blast furnace slag 4 in order to delay the d _r / d ₀ = 3 times, about gluconate Na 0 It was estimated that it was necessary to add at a ratio of 012%.

[Field test]
About the slag manufactured on the conditions similar to the blast furnace granulated slag used for the said test, the following field tests were done using the commercially available anti-caking agent (main component: about 35% of gluconate Na).
About 300 t of a test material to which 0.03% (about 0.01% as Na gluconate) of an anti-caking agent was added to the slag and a comparative material to which no anti-caking agent was added were produced and stored in a pile in the field. As a result of examining the consolidated state of the slag over time, the comparative material was confirmed to solidify after 3 weeks, but the test material to which the anti-caking agent was added showed no consolidation at the 7th week and 8 weeks. It was confirmed in the eyes.
On the other hand, according to the formula (2), it is estimated that the delay is about 2.5 times. When the comparison material is 3 weeks, the delay is 7.5 weeks. However, it was found that almost as expected results were obtained.

[Example 12]
Example 12 is an example under a temperature fluctuation environment. A sample prepared under the same conditions as in Example 9 was sealed in a container, and the change over time in the propagation time was measured while curing at a place where the temperature was changed.
The obtained result is shown in FIG. FIG. 8 shows the result of Example 9 with the result of Example 12 added to FIG. 5, and Example 12 shows the curing temperature of 19 ° C. in the legend.

The temperature at this time fluctuated as shown in FIG. Using E = 92 kJ / mol obtained in Example 9, the integrated temperature obtained by numerical integration according to this temperature fluctuation increased almost linearly as shown in FIG. The reciprocal of the consolidation characteristic value A of the blast furnace granulated slag 4 obtained in Example 9 was about 3.9 × 10 ⁻¹⁶ . The curing time required to reach this integrated temperature was determined from FIG. 9 and was about 12.5 days as indicated by the arrow.

Returning to FIG. 8, when the 50% consolidation time d ₀ of this example was determined in the same manner as the analysis performed in Example 9, it was about 12.5 days. The caking time estimated from the temperature fluctuation almost coincides with the measured value, and it has been found that the caulking time can be estimated by the present invention even when there is a temperature fluctuation.

[Example 13]
In Example 13, the sample having the sodium gluconate addition amount of 0.01% by mass of Example 11 was further carried out at curing temperatures of 30.5 ° C and 26.3 ° C. The change in propagation time is shown in FIG. 10 in comparison with Example 11 at a curing temperature of 22.1 ° C.
Was determined 50% consolidation time d _r at each curing temperature, the results in Table 6 were obtained.

D _{0 at} each curing temperature of the granulated blast furnace slag obtained in Example 9, a, n, and an added amount m = 0.01, which are indicators of the performance of the anti-caking agent obtained in Example 11. 50% consolidation time d _r estimated by applying the equation (2) well agreed with the results in Table 6.
Accordingly, the temperature dependence of the caking time when the anti-caking agent is added may be determined by considering the temperature dependence of d ₀ , and the caking time at an arbitrary temperature can be estimated. Then, it is considered that the consolidation time under temperature fluctuation can be estimated by the same method as in Example 12.

FIG. 1 is an explanatory diagram showing an example of a method and apparatus for measuring elastic wave propagation time. FIG. 2 is a graph showing the change over time in propagation time measured in Reference Example 1 and Reference Example 4 of the present invention.

FIG. 3 is a diagram showing a method for analyzing the temperature dependence of the solidification behavior. FIG. 4 is a diagram illustrating a method for analyzing the relationship between the amount of anti-caking additive added and the solidification behavior.

FIG. 5 is a graph showing the time-dependent change and analysis of the propagation time measured in Example 9. FIG. 6 is a graph showing the temporal change in propagation time measured in Example 9 and the analysis in Example 10.

FIG. 7 is a graph showing the temporal change and analysis of the propagation time measured in Example 11. FIG. 8 is a graph showing an analysis in which the result of Example 12 is added to FIG.

FIG. 9 is a diagram illustrating a method of estimating the consolidation time from the variation in the temperature at which Example 12 was implemented and the accumulated temperature. FIG. 10 is a graph showing the temporal change and analysis of the propagation time in Example 13.

Explanation of symbols

  1: Elastic wave transmitting element, 2: Elastic wave receiving element, 3: Sample, 4: Pulser, 5: Signal amplifier, 6: Oscilloscope.

Claims (7)

Using the steel slag molded body formed using the steel slag to be evaluated as a sample, the propagation time of the elastic wave propagating between two positions in the sample is continuously measured. A method for evaluating the solidification characteristics of steel slag ,
The propagation time of the elastic wave is a constant value with the same propagation time at each test temperature T (T1, T2,...) Under the condition of two or more test temperatures T (T1, T2,...). Until the time of convergence, the initial propagation time (tmax) of the steel slag compact in the time-dependent change of the measured propagation time and the convergence time (tmin) when converged to the constant value A predetermined propagation time (tx) is arbitrarily determined in between, and the curing time at each test temperature T (T1, T2,...) Until the predetermined propagation time (tx) is reached is defined as the predetermined propagation time ( calculated as the solid sintering time d ₀ to reach tx), the test temperature T (T1, T2, the relationship of the following formula ...) and the consolidation time d ₀ (1) (in the formula, R represents The constants A and E are applied to the gas constant, and the solidification characteristics are obtained from the formula (1) in which the values of the obtained constants A and E are introduced. Estimating the consolidation time d ₀ until reaching a predetermined propagation time (tx) at the environmental temperature Tx at the time of property evaluation, and estimating until the predetermined propagation time (tx) is reached at the environmental temperature Tx at the time of this solidification characteristic evaluation A method for evaluating solidification characteristics of steel slag, wherein the solidification characteristics of steel slag is evaluated from the set time d ₀ .

  The method for evaluating solidification characteristics of steel slag according to claim 1, wherein an anti-caking agent is added to the steel slag compact.   The method for evaluating solidification characteristics of steel slag according to claim 1 or 2, wherein the steel slag is granulated blast furnace slag.   The sample is a cylindrical steel slag molded body having two planes. The elastic wave is input from one plane of the molded body, and the propagation time of the elastic wave until reaching the other plane is continued. The solidification characteristic evaluation method of the steel slag according to any one of claims 1 to 3, wherein the solidification characteristic of the steel slag is evaluated from a change with time of the propagation time. The predetermined propagation time (tx) defined between the initial propagation time (tmax) and the convergence propagation time (tmin) of the steel slag compact is the initial propagation time (tmax) and the convergence propagation time ( solidifying characterization method of steel slag according to claim 1, characterized in that the logarithm of the tmin) is an intermediate value (t _50). A claim 2-5 any one solidifying properties evaluation method evaluation method of anti-caking agent using steel slag according to the, the iron and steel slag molded body wherein the anti-caking agent is added It is a method for evaluating the solidification characteristics of the steel slag from the change over time of the propagation time, and evaluating the anti-caking performance of the anti-caking agent from the solidification characteristic evaluation results of the steel slag ,
As samples of the steel slag compacts, samples with no anti-caking additive added (0) and two or more samples with different anti-caking additive added m (m1, m2,...) Were used. In the above, the propagation time of the elastic wave is continuously measured until the propagation time converges to the same constant value, and the initial propagation time (tmax) of the steel slag compact in the time-dependent change of the measured propagation time and the A predetermined propagation time (tx) is arbitrarily determined between the convergence time (tmin) when converging to a certain value, and the curing time for each sample until the predetermined propagation time (tx) is reached. Obtained as the setting time until the predetermined propagation time (tx) is reached, the setting time of the sample without addition of anti-caking agent (0) as d _0, and addition amount m (m1, m2 of anti-caking agent) , ……) are set to d _r (m1), d _r (m2), …… The relationship between the consolidation time d ₀ and the addition amount m of the anti-caking agent and the consolidation time _dr (m1), _dr (m2),. , N, and solidification until reaching a predetermined propagation time (tx) at the addition amount mx of the anti-caking agent at the time of solidification characteristic evaluation from the formula (2) in which the values of the obtained constants a and n are introduced estimating a time d _r, and wherein evaluating the solidification characteristics of the steel slag in the anticaking agent amount mx of the solidification characteristics during voted caking time d _r to reach a predetermined propagation time (tx) To evaluate anti-caking agent for steel slag.

A predetermined propagation time (tx) defined between the initial propagation time (tmax) and the convergence propagation time (tmin) is a pair of the initial propagation time (tmax) and the convergence propagation time (tmin). The method for evaluating an anti-caking agent for steel slag according to claim 6 , wherein the evaluation value is an intermediate value (t ₅₀ ).

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