JP5089341B2 - Slag separation method - Google Patents

Description

  The present invention relates to a slag separation method for separating slag into a high-concentration slag in which the limiting component restricted to be contained in the slag exceeds an allowable value and a low-concentration slag in which the limiting component is less than the allowable value. Is.

  As a technique for separating and collecting slag generated in each process of steel refining, a slag separation and collection method is known.

  This type of separation and recovery method involves recycling slag that has been collected in order to recycle the slag whose content is restricted according to its use, slag that exceeds the allowable value (high concentration slag), and slag that is less than the allowable value (low concentration slag) And then collected (see, for example, Patent Document 1).

  The above fraction collection method was obtained by determining the content of the limiting component whose content is limited in the slag generated in each step based on the refining history and / or the elimination history up to the step. The determination value is compared with the allowable value of the limit component content set according to the use, and it is determined whether the determination value exceeds the allowable value.

  Specifically, in the case of separation focusing on fluorine as a limiting component, for example, a preliminary experiment is performed in advance, desiliconization and phosphorous removal treatment is performed using a flux containing fluorite, and then 70% of slag is discharged and then discharged. A sample is taken from the slag and the fluorine content is measured.

  Next, desiliconization and phosphorus removal treatment is repeated using a flux not containing fluorine. Each time, 70% or more of slag is discharged and a sample is taken from the slag remaining in the torpedo car, and the transition of the fluorine elution amount is examined. When the amount of fluorine elution was reduced below the soil environmental standard value, how many times the cumulative number of times a was desiliconized and dephosphorized using a flux not containing fluorine and the number of times b the slag was discharged 70% or more And the accumulated value is used as a threshold value.

When the threshold value obtained in this way is used and the cumulative number a + b of the number of times of desiliconization and dephosphorization using a flux not containing fluorine and the number of times of discharging slag b is less than 6, high concentration It is regarded as slag, and when a + b is 6 or more, it is regarded as low concentration slag, and slag is collected separately.
Japanese Patent No. 3711925

  However, the amount of fluorine discharged together with the slag during slag discharge is not constant, and if the amount of fluorine remaining on the furnace wall is large, the fluorine elution amount of the sample collected decreases.

  Thus, in actual operation, the fluorine elution amount varies for each charge in the transition of the fluorine elution amount. Therefore, in the above-described conventional method in which slag is separately collected based on the excretion history, it may be determined that the slag is high-concentration slag even though it is originally low-concentration slag, and vice versa. It was difficult to accurately separate the slag.

  The present invention has been made in consideration of the problems in the conventional slag separation and recovery method as described above, and a high-concentration slag in which limiting components contained in the slag exceed an allowable value, and a low-concentration slag that is less than the allowable value. In addition, the present invention provides a slag separation method capable of accurately separating slag.

The present invention, after throwing and processing the limiting component whose content is limited into the slag, collects the slag for the next charge that does not input the same limiting component,
Crushing the slag so that at least 95% or more of the collected slag has a sphere equivalent diameter of 50 μm or less,
By pressing at a pressure of 30 t / cm ² or more and 20 seconds or more, a sample having a thickness of 2 to 4 mm and an unevenness of the analysis surface of 0.05 mm or less is formed,
With respect to the analysis surface, X-rays with a voltage of 30 kV to 40 kV and a current of 50 to 70 mA are irradiated to analyze the limiting component content,
The limit component content I obtained by the analysis is compared with a preset limit component allowable value P. When I> P, the limit component high concentration containing slag is obtained, and when P ≧ I, the limit component is low. This is a slag separation method for separation as a concentration-containing slag.

In addition, the slag fractionation method of the present invention obtains the transition of the limiting component content I in each charge for a charge that is repeatedly performed after the limiting component is charged and the same limiting component is not charged,
The difference between the first charge limit component content I ₁ and the second charge limit component content I ₂ when the limit component is less than the limit component allowable value P at the second charge after the input of the limit component is calculated. Add to the limit component allowable value P to obtain the comparison value R,
When the limiting component content I ₁ analyzed in the slag collection at the first charge after the charging of the limiting component is R ≧ I ₁ > P, the first charge has a high concentration of the limiting component and the two charges The gist is to separate the first and subsequent portions as slag containing a low concentration of the limiting component.

  An example of the limiting component in the slag fractionation method of the present invention is fluorine.

  When the limiting component is fluorine, the critical fluorine-containing concentration is obtained from the correlation equation between the fluorine-containing concentration contained in the slag and the fluorine-eluting concentration eluted from the slag into the soil, and this critical fluorine-containing concentration is calculated. The limit component allowable value can be set.

  In the slag fractionation method of the present invention, it is preferable to mold the sample without using a binder.

  As said slag in the slag classification method of this invention, refined slag can be illustrated.

  ADVANTAGE OF THE INVENTION According to this invention, slag can be correctly fractionated into the high concentration slag in which the limiting component contained in slag exceeds an allowable value, and the low concentration slag which is below an allowable value.

  Hereinafter, the present invention will be described in detail based on the embodiments shown in the drawings.

  In the present embodiment, the case where the refining slag is separated will be described as an example, but the limiting component whose content is limited is fluorine.

  The slag whose fluorine exceeds the permissible value is classified as high-concentration slag, and the slag that is less than the permissible value is classified as low-concentration slag.

  FIG. 1 shows a converter slag sampling method.

In the figure, the operation of the converter, blowing oxygen in an upright position the converter 1 from an oxygen blowing lance 2, blowing inert gas or the like from the furnace bottom, performs blowing with stirring bath.

When the blowing is completed, the furnace body of the converter 1 is tilted and molten steel is poured into the ladle 3 from the steel outlet 1a.

  At this time, the sampler 4 is inserted into the slag layer S in the converter 1, and the slag adhered to the sampler 4 and solidified is collected as a sample.

  The collected slag was pulverized using a mill (manufactured by Shimadzu, Automatic Disc Mill OD-10A type) so that 95% or more of the slag had a sphere equivalent diameter of 50 μm or less.

  Fluorine changes to a substance that volatilizes or is easily volatilized by heating. In sample preparation using glass beads that have been performed so far, when the collected slag is heated and melted, the fluorine contained in the slag is volatilized and it is difficult to accurately analyze the fluorine concentration.

  For analysis of such volatile trace elements, a briquette method for producing a sample without heating and melting is effective, but on the other hand, it is difficult to make the sample surface as smooth as a glass bead.

  In order to make the sample surface as smooth as possible when pulverizing slag as briquettes, first, as described above, the slag pulverization conditions require that 95% or more of the slag be 50 μm or less in terms of a sphere. is there.

  Furthermore, it is necessary not to add a binder to the pulverized slag. This is because if the binder is added, an error occurs in the analysis value.

Next, 60 to 70 g of the pulverized slag is weighed, and the weighed slag is filled into a steel cylinder for sample preparation. The cylinder has a diameter of 35 mm, a height of 10 mm, a thickness of 0.5 mm, and a slag filling density of about 2.8 g / cm ³ .

  Next, the cylinder filled with the slag is compressed in the cylinder axis direction using a hydraulic press device (manufactured by Shimadzu, automatic sampler SPA-10 type).

The press conditions are such that a pressure of 30 t / cm ² or more is applied for 20 seconds or more, and the obtained sample thickness is formed to 2 to 4 mm.

If an excessive pressure is applied, the sample thickness is less than 2 mm, and a flat sample surface cannot be obtained. Therefore, the pressure is preferably 40 t / cm ² or less.

  In addition, even if it takes too much press time, the sample thickness is similarly less than 2 mm, and a flat sample surface cannot be obtained.

  If the sample is prepared according to the above pulverization conditions and press conditions, the unevenness of the sample surface can be made flat, specifically 0.05 mm or less.

  FIG. 2 is a principle diagram of an apparatus for measuring unevenness of a sample surface by a light cutting method.

  In the figure, reference numeral 10 denotes a laser pointer that emits spot light. The emitted spot light is reflected by the sample surface 11 and passes through a lens 12 to form an image on a PSD (Position Sensitive Detector) 13. ing.

  Spot light reflected at point A is imaged at point A ′ of PSD 13, spot light reflected at point B is also imaged at point B ′, and when reflected at point C, it is also imaged at point C ′. Is done.

  The PSD 13 generates a voltage corresponding to the amount of light when it hits the spot light, and the potential at a point away from the spot position is lowered by the resistance of the film material. Therefore, based on the ratio of the voltages generated at both ends of the PSD 13, the imaging point Position information can be obtained.

  If the point to be measured is point A, the height of point A on the sample surface 11 can be obtained using the principle of triangulation.

  In preparing the unevenness of the sample surface to 0.05 mm, the grinding time was set to 200 seconds as the grinding conditions, and the ratio of slag having a spherical equivalent diameter of 50 μm or less after grinding was 95% or more.

  Moreover, the voltage in X-ray irradiation conditions was set to 40-50 kV, and the electric current was set to 40-50 mA.

  Fluorine fluorescent X-ray analysis was performed according to each of the above conditions. In order to confirm the effectiveness of the analysis results, a fluorine chemical analysis was performed. The results are shown in Tables 1 and 2. However, Table 2 is continuous with Table 1.

  In Tables 1 and 2, no. No. 1 indicates a charge using fluorine. No. 2 shows the first charge after using fluorine (no fluorine). 3 is the second charge, no. 4 is the third charge, no. Similarly, 5 indicates the fourth charge.

  No. 6, 11, 16, 21, 26, 31, 36, 41, and 46 indicate charges using fluorine, and from the first charge to the fourth charge, as described above, each time fluorine charge is performed. A fluorine-free charge is performed.

  For example, no. Since the fluorine charge of 1 uses fluorine, the value of fluorine concentration by fluorine fluorescent X-ray analysis is 6.343%, which is naturally a high value.

  When the fluorine-free charge is repeatedly executed after the use of fluorine (No. 2 to No. 5), the value of the fluorine fluorescent X-ray analysis value decreases step by step, and the No. 3 which is the third charge without fluorine. In No. 4, the X-ray fluorescence analysis value decreased to 0.072. 5 further decreases to 0.051. These No. 4 and no. 5, it is determined that the limiting component contained in the slag is the low-concentration slag B that is equal to or less than the allowable value.

  The allowable value (limit component allowable value) P, which is a criterion for determining the high-concentration slag and the low-concentration slag, is 0.1 wt%, and the allowable value P will be described with reference to the graph of FIG.

  There is a correlation between the fluorine-containing concentration (horizontal axis) and the fluorine elution concentration (vertical axis) based on chemical analysis, and a linear regression equation y = 5.74x can be drawn.

  Since the regulation value of the fluorine elution concentration according to the soil environment standard is 0.8 ppm, a horizontal line S is drawn from 0.8 ppm on the y-axis, and the horizontal line S intersects the point X where the linear regression equation y = 5.74x intersects. When the corresponding critical fluorine-containing concentration is determined, 0.14 wt% is obtained.

  When the limiting component contained in the slag is fluorine, the allowable value P is 0.10 wt% in which the safety factor is expected to be 0.14 wt%.

  FIG. 4 is a graph showing the relationship between the number of charges and the fluorine concentration in the slag.

  As shown in the graph, the horizontal axis shows the fluorine charge, the first charge, the second charge, the third charge, and the fourth charge after the fluorine charge, and the vertical axis shows the fluorine-containing concentration in the slag. ing. In addition, No in a graph respond | corresponds with No of Table 1 and Table 2, for example, No .. 1 to 5 are No. 1 in Table 1. It corresponds to 1-5.

  In the fluorine-free charge that is repeatedly executed after the fluorine charging and that does not charge the same limiting component, the fluorine-containing concentration gradually decreases, but the fluorine-containing concentration can be decreased. Therefore, it is difficult to determine whether the portion indicated by D in the figure is a high concentration slag or a low concentration slag by the conventional determination method.

  On the other hand, in the present invention, the allowable value P of the limiting component is set and the X-ray fluorescence analysis is performed from the actually collected sample to analyze the fluorine concentration (limiting component content) I in a short time. By comparing the result with the allowable value P, it is determined whether the slag in the charge after the fluorine charging is high concentration slag or low concentration slag. It is possible to accurately determine the charge of the portion.

Further, after the fluorine charging, the difference between the first charge limiting component content I ₁ and the second charge limiting component content I ₂ when the value falls below the allowable value P at the second charge is obtained, and this difference is determined as the above limit. The comparison value R is added to the component allowable value P.

However, the comparison value R 1 of the difference between the charge-th limit ingredient content I ₁ and second charge-th limit ingredient content I _2, it is assumed to select the smallest value.

  This comparison value R is used for the determination of high-concentration slag and low-concentration slag after the second charge described later.

  FIG. 5 shows a procedure for determining the high concentration slag and the low concentration slag.

  In the figure, the fluorine concentration I in the collected slag is analyzed by the method described above for the charge next to the fluorine input charge (step S1).

  Next, it is determined whether or not the fluorine concentration I obtained by the analysis is P ≧ I, that is, whether the allowable value P is 0.10 wt% or less (step S2).

  If the determination result is YES, it is determined that the slag after the next charge of the fluorine input charge (for example, No. 7 to 10 in Table 1 corresponds to this) is a low concentration slag (step S3).

In step S2, it is determined NO, and furthermore, the fluorine concentration _{I 1} that is analyzed in 1 charge th slag collection are, whether R ≧ _I 1> P, i.e., the fluorine concentration I is 0.10wt It is judged whether it is more than% and it is 0.30 wt% or less (step S4).

  If the determination result is YES, the slag of the next charge (for example, No. 22 charge in Table 1) of the fluorine input charge is determined to be a high concentration slag, and further, the subsequent charge (No. 23-25 charge). ) Is determined to be low-concentration slag (step S5).

  If it is determined as NO in step S4 (for example, No. 2 charge in Table 1), it is determined whether or not the fluorine concentration I exceeds 0.30% (step S6).

  If the determination result is YES, the next charge of the fluorine input charge and the next charge are determined to be high-concentration slag (No. 2 and No. 3 charges in Table 1), and further after the next charge ( About No. 4 and No. 5 charge of Table 1, it determines with low concentration slag (step S7).

  If the determination is made by analyzing the fluorine concentration for the next charge of the fluorine input charge by the above procedure and comparing it with the allowable value, No. For each charge of 1 to 50, the slag can be accurately classified into the high concentration slag A and the low concentration slag B.

  Further, comparing the determination result according to the conventional classification method and the determination result according to the present invention, it is determined that “with fluorine” in the conventional classification method, but “without fluorine” in the determination result according to the present invention. It can be seen that there are many things to be judged. Specifically, the charge No. 7, 8, 12, 13, 23, 27, 28, 38, 48.

  Conventionally, these were shipped as limited to applications where high-concentration slag was judged to be high-concentration slag, but in fact, it can be used as a low-concentration slag for a wide range of applications such as earthwork and roadbed materials. It was possible.

  FIG. 6 is a graph showing how much the fluorine-containing slag amount changes between the conventional determination method and the determination method according to the present invention.

  As shown in the graph, according to the determination method of the present invention, the amount of slag whose shipping destination is limited as high-concentration slag (this is assumed to be 1) can be reduced to the conventional 0.6. become.

  If chemical analysis is performed, highly accurate slag analysis is possible, but the analysis requires about 2 hours, and it is difficult to feed back the analysis results to the refining operation.

  On the other hand, according to the slab fractionation method of the present invention, the slag component can be analyzed in a short time to determine the slag component of the next charge after the fluorine charging, so that the slag is fed back to the refining operation. Can be used for management.

It is explanatory drawing which shows the sampling method of the converter slag which concerns on this invention. It is a principle figure of the apparatus which measures the unevenness | corrugation of the sample surface concerning this invention. It is a graph explaining the tolerance value used as the criterion of the classification method of the present invention. It is the graph which showed the relationship between the frequency | count of charge and a fluorine-containing density | concentration. It is a flowchart which shows the determination procedure of a fluorine concentration. It is the graph which compared the fluorine-containing slag amount by the conventional determination method and the determination method of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Converter 1a Steel outlet 2 Oxygen blowing lance 3 Ladle 4 Sampler 10 Laser pointer 11 Sample surface 12 Lens 13 PSD

Claims (4)

After processing the fluorine with limited content in the slag, collect the slag for the next charge without adding fluorine ,
Crushing the slag so that at least 95% or more of the collected slag has a sphere equivalent diameter of 50 μm or less,
By pressing at a pressure of 30 t / cm ² or more and 20 seconds or more, a sample having a thickness of 2 to 4 mm and an unevenness of the analysis surface of 0.05 mm or less is formed without using a binder .
The analysis surface is irradiated with X-rays having a voltage of 30 kV to 40 kV and a current of 50 to 70 mA to analyze the fluorine content,
The fluorine content I obtained by the analysis is compared with a preset fluorine allowable value P. When I> P, the fluorine-containing high-concentration slag is used. When P ≧ I, the fluorine -containing low-concentration containing slag is used. A slag sorting method characterized by sorting. After the fluorine-up, is repeated, the charge is not fluorine were charged, calculated changes in the fluorine content I of each charge,
After the fluorine-up, when below the fluorine allowable value P 2 Charge th 1 calculates the difference between the charge-th fluorine content I ₁ and second charge th fluorine content I _2, adds this difference to the fluorine allowable value P And a comparison value R
When the fluorine content I ₁ analyzed in the slag collection at the first charge after the introduction of the fluorine content is R ≧ I ₁ > P, the high-concentration fluorine- containing slag in the first charge and the second and subsequent charges The slag fractionation method according to claim 1, wherein the slag is fractionated as a fluorine -containing low-concentration slag. A critical fluorine-containing concentration is determined from a correlation equation between a fluorine-containing concentration contained in slag and a fluorine-eluting concentration eluted from the slag into the soil, and the critical fluorine-containing concentration is defined as the fluorine tolerance P. The slag separation method according to 1 or 2 . The slag separation method according to any one of claims 1 to 3 , wherein the slag is refined slag.

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