JP5549375B2 - Desulfurization slag treatment method, desulfurization flux manufacturing method, desulfurization slag continuous use method, and desulfurization slag treatment apparatus - Google Patents

Description

  The present invention relates to a method for treating desulfurization slag generated in the process of hot metal pretreatment, a method for producing a flux for deflowing, a method for continuously using desulfurization slag, and a treatment device for desulfurization slag.

  As the required level of steel quality increases, there is a strong demand for reducing the concentration of sulfur contained in steel. In general, when desulfurization is performed in a converter, the amount of flux used is increased and productivity is lowered. Therefore, pre-treatment is performed on the outside of the furnace using a flux such as calcium oxide. These fluxes react with the sulfur content in the hot metal and are discharged as desulfurized slag, and are recycled for civil engineering and cement raw materials.

  Recycling of desulfurized slag into raw materials for earthwork has problems such as high processing costs and a shortage of recycling destinations due to an increase in slag processing volume. After removal, it is desired to reuse the desulfurized slag as a flux.

  In such a situation, a method for removing sulfur from used slag that can be reused as a desulfurization material in a steelmaking process by heating the desulfurization slag to 900 ° C. or higher under a carbon dioxide gas atmosphere is disclosed (for example, Patent Document 1).

  Moreover, the processing method of the reduced slag which reduces a sulfur content by making hot water or water vapor | steam contact a reduced slag and hydrolyzing the sulfur content in reduced slag is disclosed (for example, refer patent document 2).

  Furthermore, a method for producing desulfurized slag having a low sulfur concentration is disclosed in which a gas of 70 ° C. or higher containing 15 to 50% by volume of water vapor is blown at a flow rate of 0.03 m / min to 30 m / min (see, for example, Patent Document 3). .

Furthermore, after supplying pressurized steam to a pressure vessel charged with steelmaking slag and discharging condensed hot water and steam mixed with air, the steelmaking slag is hydrated in a saturated steam atmosphere of ² to 10 kg / cm ² G. An aging method of steelmaking slag to be reacted is disclosed (for example, see Patent Documents 4 and 5).

  Moreover, the method of oxidizing and removing the sulfur in molten slag by spraying the gas containing oxygen to molten slag is disclosed (for example, refer patent documents 6-8).

JP 2008-308754 A JP 2008-163391 A Japanese Patent No. 3193869 JP-A-9-118549 JP-A-9-118550 JP-A-55-97408 JP-A-53-90193 JP 59-125386 A

  However, the method described in Patent Document 1 requires heating the slag to about 900 to 1000 ° C., which increases the energy cost.

  In addition, the methods described in Patent Documents 2 and 3 are preferable because the hydrolysis and oxidation treatment of the sulfur content in the slag requires several days, and the generated harmful hydrogen sulfide and SOx are released into the atmosphere. Absent.

  The methods described in Patent Documents 4 and 5 are aging methods aiming at hydration of free calcium oxide (free lime) in steelmaking slag, and do not describe any possibility of sulfur removal in steelmaking slag. It is not clear whether slag desulfurized by this method can be used as a flux.

  Moreover, the method of patent documents 6-8 is a desulfurization method about the sulfur contained in the molten slag, and there existed a problem that it was not applicable to the already cooled slag.

  The present invention has been devised in view of the above circumstances, and by treating desulfurized slag with high-temperature and high-pressure water, the sulfur content can be removed without releasing harmful substances such as hydrogen sulfide and SOx into the atmosphere or the ground. Method for treating desulfurized slag extracted and removed as high-temperature, high-pressure water as sulfide ions, method for producing desulfurization flux from desulfurized slag treated by the method, method for continuously using desulfurized slag, and desulfurized slag treatment apparatus The purpose is to provide.

  In order to achieve the above object, the method for treating desulfurized slag of the present invention is a method for treating desulfurized slag and water in a pressure-resistant container, and then heating the pressure-resistant container to heat the stored water at a high temperature and high pressure of 150 to 300 ° C. An extraction step of extracting the sulfur content in the desulfurized slag into the high-temperature high-pressure water by contacting the generated high-temperature high-pressure water and the desulfurized slag, and maintaining the high-temperature and high-pressure state after the extraction step is completed. And a discharging step of discharging the high-temperature and high-pressure water in the pressure vessel.

  Further, the desulfurization slag treatment method of the present invention is the above-described invention, wherein after the discharging step, water is supplied into the pressure vessel to extract a sulfur content remaining in the desulfurization slag, and the extracted water is discharged. An extraction step is included.

  In the desulfurization slag treatment method of the present invention, in the above invention, the re-extraction step supplies water into the pressure vessel and extracts a sulfur content remaining in the desulfurization slag, and then into the pressure vessel. It is characterized by blowing carbon dioxide.

  The desulfurization slag treatment method of the present invention is characterized in that, in the above invention, the desulfurization slag is heated to 500 ° C. or higher after the discharge step or after the re-extraction step.

  The desulfurization slag treatment method of the present invention is characterized in that, in the above invention, the mass ratio of desulfurization slag used in the extraction step and water is 1: 5 or more.

  The desulfurization slag treatment method of the present invention is the above-described invention, wherein the extraction step includes supplying a predetermined amount of high-temperature high-pressure water adjusted to a predetermined temperature to the pressure-resistant vessel containing the desulfurization slag, While maintaining the high temperature and high pressure state, the high temperature and high pressure water is continuously supplied into the pressure vessel and discharged to extract the sulfur content in the desulfurized slag into the high temperature and high pressure water.

  Moreover, the manufacturing method of the flux for desulfurization of hot metal of the present invention uses the desulfurization slag processed by the processing method described above to manufacture a flux to be added to remove sulfur content in hot metal. Features.

  Moreover, the continuous use method of the desulfurization slag of the present invention includes a desulfurization step of adding flux to the hot metal and removing sulfur in the added hot metal, and a separation step of separating the desulfurization slag generated in the desulfurization step from the hot metal. The desulfurized slag and water taken out in the separation step are stored in a pressure vessel, and then the water stored by heating the pressure vessel is high-temperature high-pressure water, and the generated high-temperature high-pressure water and the desulfurized slag An extraction step of extracting the sulfur content in the desulfurized slag into the high-temperature high-pressure water by contact; and a discharge step of discharging the high-temperature high-pressure water in the pressure-resistant vessel while maintaining a high-temperature high-pressure state after the extraction step is completed; The desulfurized slag from which the contained sulfur is removed is used as it is or after being mixed with a flux at a predetermined ratio, and then used as a flux in the desulfurization step.

  Moreover, the continuous use method of the desulfurization slag of this invention is the said invention. WHEREIN: The said extraction process produces | generates 150-300 degreeC high temperature high pressure water, The said high temperature high pressure water and the said desulfurization slag are contacted, and the said desulfurization is carried out. The sulfur content in the slag is extracted into the high-temperature high-pressure water.

  Moreover, the continuous use method of the desulfurization slag of this invention is the said invention. WHEREIN: After the said discharge process, water is supplied in the said pressure | voltage resistant container, the sulfur content which remains in the said desulfurization slag is extracted, and the extracted water is discharged | emitted. A re-extraction step is included.

  Further, the continuous use method of the desulfurization slag of the present invention is the above invention, wherein the re-extraction step supplies water into the pressure vessel and extracts a sulfur content remaining in the desulfurization slag, It is characterized by blowing carbon dioxide into.

  Moreover, the continuous use method of the desulfurization slag of this invention is characterized by including the process of heating the said desulfurization slag to 500 degreeC or more after the said discharge process or the said re-extraction process in the said invention.

  Moreover, the continuous use method of the desulfurization slag of this invention WHEREIN: The mass ratio of desulfurization slag used for the said extraction process and water is set to 1: 5 or more in the said invention.

  Further, the continuous use method of the desulfurized slag according to the present invention is the above invention, wherein the extraction step supplies a predetermined amount of high-temperature high-pressure water adjusted to a predetermined temperature to the pressure-resistant vessel containing the desulfurized slag, The high-temperature and high-pressure water is continuously supplied into the pressure-resistant vessel and discharged while the high-temperature and high-pressure state is maintained, and the sulfur content in the desulfurized slag is extracted into the high-temperature and high-pressure water.

  The desulfurization slag treatment apparatus of the present invention includes a pressure vessel containing desulfurization slag, a supply means for supplying water to the pressure vessel, and the water in the pressure vessel by heating the pressure vessel 150 to 150- Sulfur content in the desulfurized slag is obtained by contacting the high-temperature high-pressure water and the desulfurized slag for a predetermined time by heating means for forming high-temperature high-pressure water at 300 ° C., discharge means for discharging the high-temperature high-pressure water in the pressure-resistant vessel. And control means for controlling the high temperature and high pressure water to be discharged from the discharge means while maintaining the high temperature and high pressure state in the pressure vessel after extraction into the high temperature and high pressure water.

  The desulfurization slag treatment apparatus of the present invention is the carbon dioxide supply means for blowing carbon dioxide into the pressure vessel, and the carbon dioxide discharge means for discharging the carbon dioxide supplied by the carbon dioxide supply means. It is characterized by providing.

  In the desulfurization slag treatment apparatus of the present invention, in the above invention, the supply means includes heating means for generating high-temperature high-pressure water at 150 to 300 ° C., and the control means supplies the supply to the pressure-resistant vessel. After supplying a predetermined amount of the high-temperature and high-pressure water from the means, the high-temperature and high-pressure water is continuously supplied into the pressure-resistant container by the supply means and the drainage means while maintaining the high-temperature and high-pressure state in the pressure-resistant container. The discharge control is performed.

  According to the present invention, the sulfur content in the desulfurized slag can be extracted and removed into the high-temperature and high-pressure water only by treating the desulfurized slag generated in the hot metal pretreatment process with the high-temperature and high-pressure water for a short time. In addition, it can be used continuously as a flux of toxic substances, and furthermore, it can prevent harmful substances such as hydrogen sulfide and SOx from being released into the atmosphere, or the elution of sulfates, sulfites, etc. into the ground can be prevented. Can be small.

FIG. 1 is a cross-sectional view of a processing apparatus according to Embodiment 1 of the present invention. FIG. 2 is a flowchart of the continuous use processing of desulfurized slag according to Embodiment 1 of the present invention. FIG. 3 is a diagram showing the relationship between water temperature and saturated water vapor pressure. FIG. 4 is a cross-sectional view of the processing apparatus according to Embodiment 2 of the present invention. FIG. 5 is a flowchart of the continuous use processing of desulfurized slag according to Embodiment 2 of the present invention. FIG. 6 is a flowchart of the continuous use processing of desulfurized slag according to Embodiment 3 of the present invention. FIG. 7 is a cross-sectional view of a processing apparatus according to Embodiment 4 of the present invention. FIG. 8 is a flowchart of the continuous use processing of desulfurized slag according to Embodiment 4 of the present invention. FIG. 9 is a diagram showing the relationship between the amount of elution water and the integrated elution rate of sulfur when the high temperature and high pressure water flow treatment is performed.

  Hereinafter, preferred embodiments of a method for continuously using desulfurized slag and a processing apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

  It is well known that when water is in a liquid state at a high temperature and a high pressure, that is, a so-called subcritical state, the ionic product increases and has a large hydrolysis action. On the other hand, the desulfurized slag generated in the hot metal pretreatment includes sulfur such as sulfur, sulfite and pyrosulfate in addition to calcium sulfide taken in by the calcium compound of the flux. And it can be expected that these sulfur components are hydrolyzed by contact with the high-temperature and high-pressure water, and can be extracted into the high-temperature and high-pressure water mainly as sulfate or sulfite.

  The present invention allows high-temperature and high-pressure water to act on the desulfurized slag generated in the hot metal pretreatment, thereby quickly extracting the sulfur contained in the desulfurized slag with high-temperature and high-pressure water and discharging it without precipitation. As a result, it was considered that the sulfur content in the desulfurization slag can be removed and used as a desulfurization material for hot metal, and the present invention has been devised.

(Embodiment 1)
FIG. 1 is a cross-sectional view of a desulfurization slag treatment apparatus 100 according to Embodiment 1 of the present invention. The processing apparatus 100 accommodates desulfurized slag and serves as a reaction vessel that serves as a reaction tank that is brought into contact with high-temperature and high-pressure water, a hot water supply line system 5 that supplies hot water to the pressure-resistant sealed vessel 3, and a pressure-resistant sealed vessel 3. , A heater 4 for heating the internal water to high-temperature / high-pressure water, a treated water discharge line system 6 for discharging the high-temperature / high-pressure water in the pressure-resistant sealed container 3 after the high-temperature / high-pressure treatment, and a control unit for controlling each part 12.

  The pressure-resistant airtight container 3 has an openable / closable lid 15 for accommodating the desulfurized slag in the container. In order to perform the high-temperature high-pressure water treatment according to the first embodiment, the pressure-resistant sealed container 3 has a structure that can withstand a pressure of about 0.5 to 30 Mpa. Furthermore, it has the structure sealed so that the pressure added to the accommodated high temperature / high pressure water is not missed. The pressure-resistant sealed container 3 is placed on a container moving carriage 2 that can freely move on the container moving rail 1. The container moving rail 1 is laid so as to connect the desulfurization slag placement / cooling place and the heating heater 4 of the heat-resistant sealed container 3, and the desulfurization slag is placed in the heat-resistant sealed container at the place where the desulfurization slag is placed / cooling. 3, the heat-resistant airtight container 3 is conveyed into the heater 4 by moving the container moving carriage 2 on the container moving rail 1.

  The hot water supply line system 5 includes a hot water tank 9 for storing hot water to be supplied to the pressure-resistant sealed container 3, a heater 7 for heating the hot water in the hot water tank 9, and a temperature for detecting the temperature of the hot water in the hot water tank 9. A sensor 8, a liquid feed pump 10 for feeding hot water in the hot water tank 9 to the pressure-resistant airtight container 3, and a pressure adjusting valve 11 for adjusting the opening / closing and supply amount of the hot water supply line system 5 are provided. In the present embodiment, the hot water supply line system 5 is used to reduce the heating load of the heater 4, but the heater 7 may not be provided and water may be supplied to the heat-resistant airtight container 3.

  The amount ratio between desulfurized slag and water supplied to the pressure-resistant airtight container 3 is that the compound eluted into the high-temperature and high-pressure water by treating the desulfurized slag with the high-temperature and high-pressure water is deposited in the pipe after treatment, for example, during discharge of the treated water Therefore, it is preferable to supply water at least five times the amount of desulfurized slag so as not to cause piping clogging. Further, in order to reliably immerse desulfurized slag in high-temperature and high-pressure water and perform high-temperature and high-pressure treatment, the total charged amount (total amount of desulfurized slag and water) is set to 5% or more of the volume of the pressure-resistant sealed container 3. In order to increase the processing amount per time, it is preferable to set it to 50% or more.

  The heating heater 4 includes an openable / closable lid 16 for housing the pressure-resistant sealed container 3 and a temperature sensor 13 for detecting the temperature in the heating heater 4. The heating heater 4 heats the pressure-resistant airtight container 3 to a predetermined temperature, for example, 150 to 300 ° C., in order to use hot water supplied from the hot water supply line system 5 in the pressure-resistant airtight container 3 as high-temperature high-pressure water. The heating heater 4 according to Embodiment 1 has a structure that accommodates the heat-resistant airtight container 3, but if the water in the heat-resistant airtight container 3 can be high-temperature and high-pressure water at 150 to 300 ° C., the heat-resistant airtight container 3 is heat-resistant. It is good also as what added the heating means to airtight container 3 itself.

  The treated water discharge line system 6 includes a pressure regulating valve 14 that adjusts the opening and closing of the treated water discharge line system 6 and the discharge amount of high-temperature high-pressure water in the pressure-resistant sealed container 3.

  The control unit 12 is electrically connected to the above-described units and controls processing and operations of the units. The control unit 12 controls the heater 4 to purify the high-temperature and high-pressure water, and after contacting the desulfurized slag in the pressure-resistant sealed container 3 and the high-temperature and high-pressure water for a predetermined time, Is controlled so as to discharge the high-temperature and high-pressure water in the pressure-resistant airtight container 3. The discharge of the high-temperature and high-pressure water is performed while heating with the heater 4 so that the pressure and temperature in the pressure-tight airtight container 3 do not decrease due to the discharge of the high-temperature and high-pressure water while adjusting the discharge amount by the pressure regulating valve 14.

  As described above, the high-temperature and high-pressure water is preferably discharged while maintaining the high-temperature and high-pressure state in the heat-resistant airtight container 3, but the sulfur content such as sulfate remaining in the slag after the high-temperature and high-pressure water treatment is removed by water. In the case of re-extraction, the sulfur content remaining in the desulfurization slag can be reduced by re-extraction, so that the high-temperature high-pressure water may be discharged from the heat-resistant sealed container 3 as it is.

  Next, with reference to FIG. 2, the flow at the time of performing the continuous use process of desulfurization slag is demonstrated. FIG. 2 is a flowchart of the continuous use processing of desulfurized slag according to the first embodiment.

First, after adding a flux to pig iron manufactured in a blast furnace, the mixture is stirred and desulfurized (step S101). This desulfurization treatment (hot metal pretreatment) is performed for the purpose of removing sulfur contained in the pig iron, and is generally performed using a transport pot as a reaction vessel prior to the converter operation. Stirring is often performed by an impeller stirring method. As the flux, those conventionally used can be used as they are. Specifically, calcium oxide (also called quick lime) or a mixture of calcium oxide and aluminum cocoon is mainly used, but calcium compounds such as calcium oxide, calcium carbonate and calcium carbide, sodium carbonate, sodium hydroxide, hydroxide It is also possible to use an alkali compound such as potassium.
However, when the desulfurization process in step S101 is performed only with a new flux, a calcium compound is always included as a flux. On the other hand, in the desulfurization process of step S113 described later, when the desulfurized slag after treatment is not used as it is and is used together with a new flux, the desulfurized slag after treatment becomes a source of calcium compound, so that the new flux to be added is added. There is no need to use calcium compounds. That is, with respect to the flux used for the first flow for circulating the desulfurized slag, the flux used in combination with the desulfurized slag after treatment during the circulation may be another flux having a different ratio from the content of the mixture. Of course, it goes without saying that the present invention is effective even when the same flux having the same content and ratio is used.
In this desulfurization treatment, the sulfur content in the hot metal is taken in as calcium compounds such as CaS, CaSO3, and CaSO4, and also exists as sulfites and pyrosulfates. Most of it is estimated that calcium sulfide is taken into slag as shown by the following formula (1).

CaO + [S] = CaS + [O] (1)
Here, the desulfurized slag to be produced is composed of CaO (including hydroxide) of 40 to 50% by mass, Fe ₂ O ₃ , SiO ₂ , Al ₂ O _{3 and the} like, and S is 1 to 2 masses in terms of S. Contain about%.

  Subsequently, the desulfurization slag generated in the hot metal preliminary treatment is taken out from the transport pan and cooled (step S102).

  Thereafter, the cooled desulfurized slag is crushed (step S103). The smaller the particle size, the larger the contact area with the high-temperature and high-pressure water, and the uniform desulfurization is promoted. In order to shorten the treatment time and to uniformly desulfurize the slag, it is preferable to use one having a particle size of 10 mm or less.

  Subsequently, the crushed desulfurized slag is charged into the pressure-resistant sealed container 3 (step S104). The pressure-resistant sealed container 3 charged with desulfurization slag is moved on the container moving rail 1 by the container moving carriage 2 and accommodated in the heater 4 for heating, and then the hot water supply line system 5 and the treated water discharge line system. 6 is connected.

  After the connection, the control unit 12 opens the pressure regulating valve 11 and supplies a predetermined amount of hot water stored in the hot water tank 9 in the pressure-resistant airtight container 3 by the liquid feed pump 10 (step S105). It is desirable that the amount of supplied water be at least five times the amount of slag to be charged. In the present invention, the sulfur content contained in the desulfurized slag is extracted and removed to the treated water side by high-temperature and high-pressure water treatment. The amount of water supplied is at least 5 times the amount of slag so that the sulfur content in desulfurized slag hydrolyzed and oxidized by high-temperature and high-pressure water treatment can be eluted to the treated water side as much as possible without precipitating. .

  The control unit 12 closes the pressure regulating valve 10 of the hot water supply line system 5, then raises the temperature of the heater 4 for heating, and heats the water in the heat-resistant airtight container 3 to a high temperature and high pressure at a predetermined temperature of 150 to 300 ° C. The desulfurized slag is treated with high-temperature and high-pressure water after being kept for a certain time (step S106). Although the optimum treatment time varies depending on the particle size and sulfur content of the desulfurized slag, the treatment time is sufficient in about 2 to 3 hours in the high-temperature and high-pressure water treatment at 150 to 300 ° C. Further, the water pressure of the high-temperature high-pressure water is adjusted to be equal to or higher than the saturated vapor pressure of water at the predetermined temperature described above. In addition, what is necessary is just to use a well-known method and a value for the calculation method of the saturated vapor pressure of water in predetermined temperature. FIG. 3 is a diagram showing the relationship between the water temperature and the water vapor pressure calculated by the Wagner equation shown by the following equations (2) and (3). According to FIG. 3, the saturated water vapor pressure of water is, for example, 0.48 MPa at 150 ° C. and 8.6 MPa at 300 ° C. From this, the saturated vapor pressure or higher of water at the predetermined temperature is, for example, 0.48 MPa or higher at 150 ° C. and 8.6 MPa or higher at 300 ° C.

ln (p × [kPa] Pc) = (Aτ + Bτ ^1.5 + Cτ ³ + Dτ ⁶ ) / (T / Tc)
(2)
τ = 1−T [K] / Tc (3)
In the above formulas (2) and (3), A = −7.76451, B = 1.45838, C = −2.7758, D = −1.23303, Tc = 647.3K, Pc = 22120 kPA (use range) 275K to 647.3K).

The sulfur content in the desulfurized slag, mainly calcium sulfide, is converted into calcium sulfate by hydrolysis and oxidation treatment with high-temperature and high-pressure water as shown in the following formula (4), and then converted into calcium sulfate. Is estimated to be extracted. The solubility of calcium sulfate is at least 10 times that of calcium sulfide, and it is easily dissolved in water and easily removed from desulfurized slag by being converted to calcium sulfate by high-temperature and high-pressure treatment.
2CaS + 10H ₂ O → H ₂ SO ₄ + CaSO ₄ + Ca (OH) ₂ + 3H ₂ (4)
In the right side of the equation (4), the sulfur content in H ₂ SO ₄ and CaSO ₄ is extracted into high-temperature high-pressure water.

  After the high-temperature and high-pressure water treatment, the treated water is discharged from the pressure tight container 3 while maintaining the high-temperature and high-pressure state (step S107). The control unit 12 adjusts the pressure adjusting valve 14 to adjust the discharge amount of the high-temperature and high-pressure water, and controls the heating of the heater 4 so that the pressure and temperature in the pressure-resistant sealed container 3 do not decrease.

  After discharging the high-temperature and high-pressure water, the control unit 12 supplies cold water from a bypass line (not shown) of the hot water supply line system 5 (step S108), and again extracts sulfur content such as calcium sulfate remaining in the desulfurized slag into water. (Step S109). Calcium sulfate, which is estimated to be generated by high-temperature and high-pressure treatment, is eluted in a large amount of water in high-temperature and high-pressure conditions compared to normal temperature and normal pressure, but sulfur content such as calcium sulfate exceeding the saturation amount is precipitated as a solid. Will remain on the surface of the desulfurized slag. When used as a flux, the performance decreases if the total sulfur concentration is high regardless of the form. Therefore, reextraction of sulfur such as calcium sulfate with cold water of desulfurized slag reduces the residual sulfur concentration. This is preferable. The re-extraction process with water is a process for further improving the efficiency of desulfurization from desulfurized slag, and when the sulfur content can be removed in the processes up to step S107 (when the concentration of sulfur in the desulfurized slag is not large or This is not necessarily a necessary process when the initial water supply amount is increased.

  After the re-extraction step with water, the control unit 12 controls the pressure regulating valve 14 of the treated water discharge line system 6 to discharge water (step S110), and the heating is performed with the pressure regulating valve 14 opened. The heater 4 is heated to dry the treated desulfurized slag (step S111). Although the time required for drying can be shortened by heating and drying with the heater 4 for heating, it is not necessarily a necessary process and may be natural drying.

  After the desulfurization slag is dried, the hot water supply line system 5 and the treated water discharge line system 6 are disconnected, the pressure-resistant sealed container 3 is carried out of the heater 4 for heating, and the container moving rail 1 is moved by the container moving carriage 2. The top is transferred and transported to the hot metal pretreatment facility (step S112).

  In the hot metal pretreatment facility, the treated desulfurized slag can be used as it is or after being mixed with a new flux at a predetermined ratio and then added to the hot metal (step S113). In addition, what is necessary is just to determine suitably the mixing ratio of the desulfurization slag after a process, and a new flux according to the desulfurization amount which the desulfurization process currently performed requires.

  According to the continuous use method and treatment apparatus for desulfurized slag of the first embodiment, the sulfur content in the desulfurized slag can be extracted into water in a short time with high-temperature and high-pressure water having a high ionic product. Therefore, it can be recycled as a flux in the hot metal pretreatment.

(Embodiment 2)
The continuous use method and processing apparatus of desulfurization slag concerning this Embodiment 2 improves the performance as a flux by converting calcium hydroxide into calcium carbonate.

  FIG. 4 is a cross-sectional view of a desulfurization slag treatment apparatus 200 according to Embodiment 2 of the present invention. Hereinafter, only parts different from the processing apparatus 100 according to the first embodiment will be described with reference to FIG.

  As shown in FIG. 4, the processing apparatus 200 further includes a carbon dioxide supply line system 17 and a carbon dioxide discharge line system 18.

  The carbon dioxide supply line system 17 includes a pressure adjusting valve 19 that opens and closes the carbon dioxide supply line system 17 and adjusts the amount of carbon dioxide supplied into the pressure-resistant sealed container 3.

  The carbon dioxide discharge line system 18 includes a pressure regulating valve 20 that adjusts the opening / closing of the carbon dioxide supply line system 18 and the discharge amount of carbon dioxide from the pressure-resistant sealed container 3.

  The control unit 22 adjusts the pressure of the carbon dioxide supply line system 17 in the pressure tight sealed container 3 when performing re-extraction treatment of the desulfurized slag with cold water after the high temperature and high pressure treatment of the desulfurized slag in the pressure tight sealed container 3 is completed. The valve 19 is controlled to supply carbon dioxide, and excess carbon dioxide is discharged by controlling the pressure regulating valve 20 of the carbon dioxide discharge line system 18.

  Next, with reference to FIG. 5, the flow at the time of performing the continuous use process of the desulfurization slag concerning Embodiment 2 is demonstrated. FIG. 5 is a flowchart of the continuous use process of desulfurized slag according to the second embodiment.

  Steps S201 to S209 are performed in the same manner as steps S101 to S109 of the continuous use process of the first embodiment.

  After the re-extraction process with water (step S209), the control unit 22 controls the pressure regulating valve 19 of the carbon dioxide supply line system 17 to supply carbon dioxide into the pressure-resistant sealed container 3 (step S210). The supplied carbon dioxide and calcium hydroxide in the desulfurized slag can be reacted to form calcium carbonate with higher flux performance. In addition, calcium dissolved in water can be recovered as calcium carbonate by reacting with the supplied carbon dioxide. The controller 22 supplies an excessive amount of carbon dioxide, and the carbon dioxide that has not been used for the reaction is discharged from the pressure-resistant sealed container 3 by controlling the pressure regulating valve 20 of the carbon dioxide discharge line system 18. Instead of installing the carbon dioxide supply line system 17 and the carbon dioxide discharge line system 18, carbonated water is supplied from the hot water supply line system 5 to extract the remaining calcium sulfate and to treat the calcium hydroxide. May be performed simultaneously.

  After the carbonic acid treatment of calcium hydroxide, as in the first embodiment, the water in the pressure-resistant airtight container 3 is discharged (step S211), and the desulfurization slag is dried by raising the temperature of the heater 4 (step S212). After transporting to the pretreatment facility (step S213), the treated desulfurized slag can be used alone or after being mixed with a new flux at a predetermined ratio and then added to the hot metal (step S214). In addition, what is necessary is just to determine suitably the mixing ratio of the desulfurization slag after a process, and a new flux according to the desulfurization amount which the desulfurization process currently performed requires. In addition, the new flux mixed at this time does not need to contain a calcium compound, as in step S113 of the first embodiment described above.

(Embodiment 3)
The continuous use method and processing apparatus for desulfurized slag according to the third embodiment converts calcium hydroxide into calcium carbonate, and then converts the calcium carbonate or remaining calcium hydroxide into calcium oxide having higher desulfurization ability. , Improve the performance as a flux.

  The continuous use method and processing apparatus of desulfurized slag according to the third embodiment is obtained by oxidizing the calcium carbonate or the remaining calcium hydroxide after converting the calcium hydroxide into calcium carbonate by the method and apparatus according to the second embodiment. This is converted to calcium, and can be performed using the processing apparatus 200 of the second embodiment.

  With reference to FIG. 6, the flow at the time of performing the continuous use process of the desulfurization slag concerning Embodiment 3 is demonstrated. FIG. 6 is a flowchart of the continuous use process of desulfurized slag according to the third embodiment.

  Steps S301 to S311 are performed in the same manner as steps S201 to S211 of the continuous use process of the second embodiment.

  After the carbonic acid treatment of calcium hydroxide, the water in the pressure-resistant sealed container 3 is discharged (step S311), the heater 4 is heated, and the desulfurized slag is heated to 500 ° C. or higher (step S312). By heating to 500 ° C. or higher, residual moisture is removed, and decarboxylated and unreacted calcium hydroxide is dehydrated from the converted calcium carbonate to convert it into calcium oxide having higher desulfurization efficiency.

  After conversion to calcium oxide, the desulfurized slag is cooled and transported to the hot metal pretreatment facility (step S313), and the treated desulfurized slag is used alone or mixed with a new flux at a predetermined ratio and then added to the hot metal for use. (Step S314). In addition, what is necessary is just to determine suitably the mixing ratio of the desulfurization slag after a process, and a new flux according to the desulfurization amount which the desulfurization process currently performed requires. In addition, the new flux mixed at this time does not need to contain a calcium compound, as in the case of step S113 in the first embodiment and step S214 in the second embodiment.

  In this Embodiment 3, after converting calcium hydroxide into calcium carbonate, the calcium carbonate or remaining calcium hydroxide is converted into calcium oxide having a higher desulfurization capability. After supplying (step S308) and reextracting the remaining sulfur content such as calcium sulfate (step S309), the extracted water is discharged without supplying carbon dioxide (step S311), and the slag is dried at 500 ° C. or higher. By doing so (step S312), the calcium hydroxide may be directly dehydrated and converted to calcium oxide having higher desulfurization performance.

  Alternatively, after discharging water under high-temperature and high-pressure treatment without performing re-extraction treatment and carbonation treatment with water (step S307), the slag is dried at 500 ° C. or higher (step S312), and from calcium hydroxide. It is also possible to perform direct dehydration and convert to calcium oxide with higher desulfurization performance.

(Embodiment 4)
The continuous use method and processing apparatus for desulfurized slag according to the fourth embodiment includes a flow process of discharging the desulfurized slag and the high-temperature high-pressure water while continuously supplying the high-temperature high-pressure water directly to the pressure vessel. To do. In the fourth embodiment, since the supply ratio to the desulfurization slag of high-temperature and high-pressure water can be increased, it is possible to improve the extraction capacity of sulfur components such as generated calcium sulfate.

  FIG. 7 is a cross-sectional view of a desulfurization slag treatment apparatus 300 according to Embodiment 4 of the present invention. Hereinafter, only parts different from the processing apparatus 100 according to the first embodiment will be described with reference to FIG.

  The processing apparatus 300 includes a high-temperature and high-pressure water supply line system 30 instead of the hot water supply line system 5. The high-temperature high-pressure water supply line system 30 includes a water storage tank 31 that stores water, a coil 33 that converts supplied water into high-temperature high-pressure water, and a heater 4 that heats the coil 33 to generate high-temperature high-pressure water. And a liquid feed pump 32 for feeding high-temperature high-pressure water to the hermetic pressure vessel 3 through the coil 33.

  The coil 33 is accommodated in the heater 4 for heating the pressure-resistant airtight container 3, and the water fed by the liquid feed pump 32 is heated while circulating through the coil 33 and converted into high-temperature and high-pressure water. The In order to supply the desired high-temperature and high-pressure water into the pressure-resistant airtight container 3 via the coil 33, the liquid feed pump 32 uses a pump having a maximum working pressure that is equal to or higher than the desired pressure. In the fourth embodiment, the coil 33 and the pressure-resistant airtight container 3 are heated by one heating heater 4, but another heating source may be provided.

  The control unit 34 controls the processing and operation of each unit, and after supplying a predetermined amount of high-temperature and high-pressure water into the pressure-resistant sealed container 3 by the high-temperature and high-pressure water supply line system 30, holds the high-temperature and high-pressure state in the pressure-resistant sealed container 3 On the other hand, the high-temperature high-pressure water supply line system 30 and the treated water drainage line system 6 are controlled so that the high-temperature high-pressure water is continuously supplied into the pressure-resistant sealed container 3 and discharged.

  Next, with reference to FIG. 8, a flow when the desulfurization slag according to Embodiment 4 is continuously used with high-temperature and high-pressure water will be described. FIG. 8 is a flowchart of the continuous use treatment of the desulfurized slag according to the fourth embodiment with high-temperature and high-pressure water.

  Steps S401 to S404 are performed in the same manner as steps S101 to S104 of the continuous use process of the first embodiment.

  After the pressure-resistant airtight container 3 charged with desulfurized slag is accommodated in the heater 4 for heating, it is connected to the high-temperature high-pressure water supply line system 30 and the treated water discharge line system 6. After the connection, the control unit 34 adjusts the temperature of the pressure tight container 3 and the coil 33 to a predetermined temperature of 150 to 300 ° C. by the heater 4 (step S405).

  After adjusting the temperature of the pressure tight container 3 and the coil 33, a predetermined amount of high temperature and high pressure water is supplied into the pressure tight container 3 by the high temperature and high pressure water supply line system 30 (step S406). The water stored in the storage tank 31 is supplied to the coil 33 by the liquid supply pump 32 and is converted into high-temperature and high-pressure water by circulating through the coil 33 adjusted to a predetermined temperature. To be supplied.

  The controller 34 supplies a predetermined amount of high-temperature and high-pressure water into the pressure-resistant sealed container 3 through the high-temperature and high-pressure water supply line system 30, and then continuously supplies high-temperature and high-pressure water into the pressure-resistant sealed container 3 through the high-temperature and high-pressure water supply line system 30. At the same time, the pressure regulating valve 14 of the treated water drainage line system 6 is adjusted so as to be discharged from the pressure-resistant sealed container 3. The control unit 34 adjusts and controls the liquid feed pump 32 and the pressure regulating valve 14, thereby maintaining the pressure and temperature in the pressure-resistant airtight container 3 and subjecting the desulfurized slag to be stored to high-temperature and high-pressure processing (step S407). The treatment time varies depending on the particle size and sulfur content of the desulfurized slag, and the amount of high-temperature and high-pressure water to be supplied.

  After the high-temperature and high-pressure water treatment, the treated water is discharged from the pressure-resistant sealed container 3 (step S408). After stopping the liquid feed pump 32, the controller 34 controls the heating of the heater 4 so that the pressure and temperature in the pressure-resistant sealed container 3 do not decrease, while treating the high-temperature and high-pressure water in the pressure-resistant sealed container 3 with treated water. Discharge from the discharge line system 6. In the fourth embodiment, since the high-temperature high-pressure water is flow-processed to continuously supply / discharge the pressure-resistant sealed container 3, the sulfur extracted in the high-temperature high-pressure water continuously from the treated water discharge line system 6 together with the high-temperature high-pressure water. Are being discharged. For this reason, the sulfur content concentration in the discharged high-temperature and high-pressure water is a very small value as compared with the first embodiment. Therefore, after treatment with high-temperature and high-pressure water, even if the pressure drops to normal pressure before discharging the treated water, there is little reprecipitation of the sulfur content, and the post-treated water at normal pressure may be discharged.

  After the treated water is discharged, the control unit 34 raises the temperature of the heater 4 with the pressure regulating valve 14 of the waste water treatment line system 6 opened, and dries the treated desulfurized slag (step S409). After the slag is conveyed to the hot metal pretreatment facility (step S410), the treated desulfurized slag can be used alone or after being mixed with a new flux at a predetermined ratio and then added to the hot metal (step S411). . In addition, what is necessary is just to determine suitably the mixing ratio of the desulfurization slag after a process, and a new flux according to the desulfurization amount which the desulfurization process currently performed requires. In addition, the new flux mixed at this time does not need to contain a calcium compound, as in step S113 of the first embodiment described above.

  In the fourth embodiment, the supply amount of high-temperature high-pressure water can be set large by performing flow treatment by simultaneously supplying and discharging high-temperature high-pressure water, so that the initial desulfurization slag into the pressure-resistant sealed container 3 can be set. The charging amount can be set larger than that in the first embodiment, and the processing amount per time can be increased. Moreover, since it is easy to increase the high-temperature and high-pressure water ratio with respect to desulfurization slag, it becomes possible to remove sulfur content reliably and to reuse as a flux having excellent desulfurization performance.

  Further, the slag treated with the high-temperature and high-pressure water in the flow treatment of Embodiment 4 is further treated with carbon dioxide to be carbonated, or heated to 500 ° C. or higher to be dehydrated, so that it can be regenerated as a flux with excellent desulfurization performance. It can be used.

Example 1
Desulfurized slag (sulfur content: 1.79%) adjusted to a particle size of 2 mm or less in the pressure vessel and 5 times the amount of water as desulfurized slag are housed, and the pressure vessel is sealed, and then adjusted to 75 to 300 ° C. And kept in an air oven for 6 hours. After a predetermined time, the pressure vessel was taken out from the air oven and allowed to cool, and the water in the pressure vessel was filtered with 5B filter paper, and the slag was allowed to stand at room temperature and dried. About the slag after a high temperature / high pressure process, the content rate of a sulfur content was measured, and the ratio with respect to the sulfur content rate before a process was calculated | required as an extraction rate. The results are shown in Table 1.

  As shown in Table 1, the extraction rate increased as the heating temperature increased, and the extraction rate was 40% or higher at 150 ° C. or higher.

  The hydrolyzing action of high-temperature and high-pressure water is greatest at around 200 to 250 ° C. where the ionic product of water is maximized, and heat treatment significantly exceeding 250 ° C. places a burden on facilities and energy. There is a possibility that the solubility of sulfate that is considered to be generated by hydrolysis is lowered, and the amount of sulfate remaining in the slag is increased. In addition, when the water temperature exceeds 374 ° C., which is 22.1 Mpa, the dielectric constant of water is greatly reduced. Therefore, it is considered that ionic substances such as thiosulfate ions and orthosulfate ions, which are thought to be generated by hydrolysis, are used. It becomes difficult to dissolve sulfur oxide ions. Furthermore, as the pressure and temperature increase, equipment with a large apparatus configuration is required. Therefore, it is preferable that the treatment with high-temperature and high-pressure water at 300 ° C. or lower is practical.

(Example 2)
High-performance liquid chromatography was remodeled, and high-temperature and high-pressure water treatment of desulfurized slag was performed by flow treatment. The column portion of the high performance liquid chromatography apparatus was replaced with a stainless steel pressure vessel, and 10 g of desulfurized slag (sulfur content 1.79%) whose particle size was adjusted to 2 mm or less was filled in the pressure vessel. High-temperature and high-pressure water at 250 ° C. and 18 Mpa was continuously supplied to the pressure vessel (0.6 ml / hr, total supply amount 350 ml). The high-temperature and high-pressure water discharged from the pressure vessel was separated by cooling, and the elution amount of sulfur extracted in the water was analyzed. The results are shown in FIG.

  FIG. 9 is a diagram showing the relationship between the amount of elution water and the integrated elution rate of sulfur when the high temperature and high pressure water flow treatment is performed. As shown in FIG. 9, it can be seen that about 70% of sulfur content was extracted with 100 ml (10 times the amount of slag) and over 90% with 200 ml. Since high-temperature and high-pressure water has very high hydrolysis and oxidizing power, it is presumed that the sulfur content in slag is converted to sulfate or the like in a short time. When using desulfurized slag as a flux, the lower the total sulfur content (including sulfates), the better the desulfurization action. Therefore, increase the amount of water supplied to the desulfurized slag or re-extract with water after high-temperature and high-pressure water treatment. It is preferable to process.

  As described above, the desulfurization slag continuous use method and treatment apparatus of the present invention can be used in a steelmaking process, and is particularly suitable for use in the desulfurization process of pig iron in hot metal pretreatment.

DESCRIPTION OF SYMBOLS 1 Container moving rail 2 Container moving cart 3 Pressure-resistant airtight container 4, 7 Heating heater 5 Hot water supply line system 6 Treated water discharge line system 8, 13 Temperature sensor 9 Hot water tank 10, 32 Liquid feed pump 11, 14, 19 , 20 Pressure regulating valve 12, 22, 34 Control unit 15, 16 Lid 17 Carbon dioxide supply line system 18 Carbon dioxide discharge line system 30 High temperature / high pressure water supply line system 31 Water tank 33 Coil 100, 200, 300 Processing device

Claims (17)

An extraction step in which desulfurized slag is brought into contact with 150 to 300 ° C. high-temperature high-pressure water in a pressure-resistant container, and sulfur content in the desulfurized slag is extracted into the high-temperature high-pressure water by contact between the high-temperature high-pressure water and the desulfurized slag; ,
After the extraction step is completed, a discharge step of discharging the high-temperature high-pressure water in the pressure vessel while maintaining a high-temperature and high-pressure state;
A process for treating desulfurized slag, comprising:   2. The desulfurization process according to claim 1, further comprising a re-extraction step of supplying water into the pressure-resistant vessel after the discharging step, extracting a sulfur content remaining in the desulfurization slag, and discharging the extracted water. Slag processing method.   3. The desulfurization according to claim 2, wherein in the re-extraction step, carbon is blown into the pressure-resistant container after supplying water into the pressure-resistant container and extracting a sulfur content remaining in the desulfurization slag. Slag processing method.   The processing method of desulfurization slag as described in any one of Claims 1-3 including the process of heating the said desulfurization slag to 500 degreeC or more after the said discharge process or the said re-extraction process.   The desulfurization slag treatment method according to any one of claims 1 to 4, wherein a mass ratio of desulfurization slag and water used in the extraction step is 1: 5 or more.   In the extraction step, after supplying a predetermined amount of high-temperature and high-pressure water adjusted to a predetermined temperature to the pressure-resistant vessel containing desulfurized slag, the high-temperature and high-pressure water is supplied to the pressure-resistant vessel while maintaining the high-temperature and high-pressure state in the pressure-resistant vessel. The method for treating desulfurized slag according to claim 1, wherein the sulfur content in the desulfurized slag is extracted into the high-temperature and high-pressure water by being continuously supplied and discharged. . A desulfurization of hot metal, characterized by producing a flux to be added to remove sulfur content in hot metal using the desulfurization slag treated by the treatment method according to any one of claims 1 to 6. Of manufacturing flux. A desulfurization step of adding flux to the hot metal and removing sulfur content in the added hot metal;
A separation step of separating the desulfurized slag produced in the desulfurization step from the hot metal;
In the pressure vessel, the desulfurization slag taken out in the separation step is brought into contact with high-temperature high-pressure water at 150 to 300 ° C., and the sulfur content in the desulfurization slag is reduced by the contact between the high-temperature high-pressure water and the desulfurization slag. Extraction process to extract into,
After the extraction step is completed, a discharge step of discharging the high-temperature high-pressure water in the pressure vessel while maintaining a high-temperature and high-pressure state;
Including
A method for continuous use of desulfurized slag, wherein the desulfurized slag from which contained sulfur has been removed is used as a flux in the desulfurization step as it is or after being mixed with a flux at a predetermined ratio.   The extraction step generates high-temperature and high-pressure water at 150 to 300 ° C., and the sulfur content in the desulfurized slag is extracted into the high-temperature and high-pressure water by contact between the generated high-temperature and high-pressure water and the desulfurized slag. The continuous use method of the desulfurization slag of Claim 8.   10. The method according to claim 8, further comprising a re-extraction step of supplying water into the pressure-resistant vessel after the discharging step to extract a sulfur content remaining in the desulfurization slag and discharging the extracted water. Continuous use of desulfurized slag.   The desulfurization method according to claim 10, wherein the re-extraction step includes supplying water into the pressure vessel and extracting sulfur remaining in the desulfurization slag, and then blowing carbon dioxide into the pressure vessel. How to use slag continuously.   The method for continuously using desulfurized slag according to any one of claims 8 to 11, further comprising a step of heating the desulfurized slag to 500 ° C or higher after the discharging step or the re-extracting step.   The method for continuously using desulfurized slag according to any one of claims 8 to 12, wherein a mass ratio of desulfurized slag and water used in the extraction step is 1: 5 or more.   In the extraction step, after supplying a predetermined amount of high-temperature and high-pressure water adjusted to a predetermined temperature to the pressure-resistant vessel containing desulfurized slag, the high-temperature and high-pressure water is supplied to the pressure-resistant vessel while maintaining the high-temperature and high-pressure state in the pressure-resistant vessel. The continuous use of desulfurized slag according to any one of claims 8 to 12, wherein the sulfur content in the desulfurized slag is extracted into the high-temperature and high-pressure water by being continuously supplied and discharged. Method. A pressure vessel containing desulfurization slag ;
Discharging means for discharging high-temperature and high-pressure water in the pressure vessel;
After extracting the sulfur content in the desulfurized slag into the high-temperature and high-pressure water by bringing the high-temperature and high-pressure water at 150 to 300 ° C. into contact with the desulfurized slag for a predetermined time in the pressure-resistant vessel, the high-temperature and high-pressure state in the pressure-resistant vessel is changed. Control means for controlling to discharge the high-temperature high-pressure water from the discharge means while holding;
An apparatus for treating desulfurization slag, comprising: Carbon dioxide supply means for blowing carbon dioxide into the pressure vessel,
Carbon dioxide discharge means for discharging carbon dioxide supplied by the carbon dioxide supply means;
The processing apparatus of the desulfurization slag of Claim 15 characterized by the above-mentioned. Providing supply means for generating the high-temperature high-pressure water and supplying the generated high-temperature high-pressure water to the pressure vessel,
The control means supplies a predetermined amount of the high-temperature and high-pressure water from the supply means into the pressure-resistant container, and then maintains the high-temperature and high-pressure state in the pressure-resistant container while the high-temperature and high-pressure water is supplied by the supply means and the drainage means. The desulfurization slag treatment apparatus according to claim 15 or 16, wherein control is performed to continuously supply and discharge water into the pressure vessel.

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