JPH07110774B2 - Method and apparatus for treating molten slag - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a method for treating desulfurization slag of hot metal in a pig iron factory or a foundry, and specifically, desulfurization slag (deslag) after desulfurization treatment of hot metal. , Especially residual calcium carbide (Ca
The present invention relates to a processing device for processing C ₂ ) harmlessly.

[Prior Art] Conventionally, the sulfur content contained in the hot metal has a bad influence on the product in terms of material quality, and particularly when smelting ductile cast iron, it is a major impediment factor in spheroidizing carbon. It must be removed in advance. In the sulfur removal treatment (hereinafter referred to as "desulfurization"), a commercially available desulfurizing agent mainly composed of calcium carbide is heated from the tap pond 10a of the hot metal furnace such as kiyupora to the main pot 11a as shown in Fig. 2A. N ₂ from the porous plugs 12a that were inserted at the same time and fitted in the bottom of the ladle.
Inject gas to bubbling the molten metal vigorously to make sufficient contact. At this time, the sulfur in the molten metal separates and moves into the molten slag that floats on the molten metal, so desulfurization is completed by scraping the molten slag from the molten metal as shown in FIG. 2B.

[Problems to be solved by the invention] Slag is an unfavorable problem in terms of safety and environment in the workplace because an input agent such as calcium carbide is slagged at a high temperature and contains a large amount of sulfur transferred from the hot metal. Occurs.

That is, desulfurization slag, especially calcium carbide, comes into contact with the hot metal to have the following composition.

Calcium oxide (CaO), calcium sulfide (CaS), phosphide calcium (Ca ₃ P _2), unreacted calcium carbide in (CaC ₂₎ others. In particular, calcium carbide and calcium phosphide contact with water in the atmosphere or other water to rapidly react.

C ₂ H ₂ or acetylene gas is an explosive gas, which is dangerous and dangerous because it easily ignites and burns due to the residual heat of the desulfurized slag to be discarded, and H ₃ P or hydrogen phosphide aka phosphine. Is a toxic gas and gives off a foul odor.

Therefore, it is not preferable to discard the desulfurization slag as it is, and therefore a method has been added on site to eliminate CaC ₂ and Ca ₃ P ₂ in the slag. In order to achieve that purpose, it is sufficient to completely react the charged calcium carbide desulfurizing agent with the sulfur in the hot metal to eliminate the residual calcium carbide (CaC ₂ ). Considering the contact efficiency with the desulfurization agent and the treatment time, it is inevitable that the calcium carbide desulfurization agent remains in the slag unreacted. In addition, calcium phosphide (Ca ₃ P ₂ ) is also caused by phosphorus (P) as an impurity that comes in during the calcium carbide manufacturing process, which is also unavoidable for solving problems. Has not arrived.

In the prior art disclosed in Japanese Patent Laid-Open No. 51-111469, as shown in FIG. 3, when removing molten metal from a hot metal ladle 11a through a cylindrical chute, the inside of the chute 101 and the ladle la 1a.
Disclosed is a configuration in which oxygen is supplied to both or one of the surfaces to bring it into contact with a slag to burn the remaining carbide in the slag to render it harmless, and to supplement malodorous gas and soot and dust through a hood 102 provided above the chute. ing. That is, it is recognized that the present application has a common point with the problem to be solved for the purpose of burning and detoxifying the carbide remaining in the desulfurization slag after removing the slag. As a function of this structure, in this prior art, the mouth of the hot metal ladle is tilted toward the upper opening of the cylindrical chute, and the slag on the surface of the hot metal is made to flow down into the cylindrical chute with a scraping rod and is discharged to the ladle. Oxygen is ejected from the oxygen supply pipe into the chute, and oxygen is forcibly brought into contact with the slag passing through the chute to accelerate the reaction.
He also claims that the slag that has already entered the pot will be contacted with oxygen from the oxygen supply tube to complete the reaction.

However, in this configuration, the injected oxygen induces violent combustion on the surface of the flowing slag, and the surface temperature of the slag further rises and the fluidity increases, but the combustion mainly on the liquid slag surface Seen from the flow of the slag as a whole, it stays in a very local area, and most of the slag flows down while being blocked from contact with oxygen by the slag on the surface and reaches Noro pot 1a. I don't get. The slag that reaches the Noro pot loses its heat and begins to solidify rapidly, and tries to release a large amount of combustible gas as it solidifies and cools down, but here again there is an injection of oxygen toward the surface of the slag, and the slag is Only its surface is heated and remains in a liquid state, and the lower part thereof solidifies without contact with oxygen and prevents the combustion extinguishing effect of combustible gas. As the slag accumulates and the solidified part below condenses in a lump as the temperature drops, it is unlikely that the purpose of preventing the deterioration of the environment will be achieved and that the harmful and toxic gas components will be consumed by combustion. large.

In order to solve the above-mentioned problems, the present invention aims to provide a method and a device for completely treating the generated slag and for completely treating the toxic and harmful gas contained therein.

[Means for Solving the Problems] The method for treating molten slag according to the present invention is such that, when hot metal is received in a ladle, a deoxidizer is added from above the ladle and an inert gas is discharged from the bottom of the ladle. This is a desulfurization process of molten pig iron that separates and removes the generated molten slag from the molten metal.The molten slag is allowed to naturally flow down from the top end of the ladle into the processing tank immediately below, and the heat quantity of the molten slag that has flowed down is retained in the processing tank side While the molten slag solidifies in the temperature range of 300 to 600 ℃ or more due to the cooling action from the refractory tank that was introduced to No. 1, it does not aggregate into lumps but continuously maintains powder form and continues powder boiling. By injecting a controlled amount of compressed air almost uniformly from the bottom surface of the treatment layer, and continuing the low temperature combustion of the combustible gas contained in the powder from beginning to end by continuously contacting the air jet and the flow that reaches the entire amount of the residue. Solved the problem.

In addition, as an apparatus used for carrying out the method, the side wall is dressed with the refractory layer 3 and the bottom surface of the cylindrical body 2 is opened and closed with a hinge 6 as a fulcrum so that only the upper surface is a perforated plate 4.
The problem can be solved by a structure in which a hollow box 5 made of is attached and a compressed air supply port is attached to the side surface of the hollow box 5 so that the air volume can be freely adjusted.

[Operation / Embodiment] The operation of the present invention will be described with reference to FIG.

FIG. 1 shows an overall view of the embodiment of the present application, in which the processing apparatus 1 has a refractory layer 3 deposited on the inner wall of a tubular body 2. A hollow box 5 having a perforated plate 4 only on the upper surface of the cylindrical body 2 is detachably locked to a lower bottom portion by a butterfly shape 6. A compressed air supply port 7 is attached to the hollow box 5 at the bottom, and an air flow rate adjusting valve is provided in the middle of a pipe line from the compressed air source (not shown). In addition, in practice, it is preferable that the wall has a downward slope as shown in the figure.

The hot metal F is received from the tap iron gutter 10 of the hot metal furnace to the ladle 11, and at this time, the desulfurizing agent D containing CaC ₂ + CaO as a main component is added at the same time and enters the hot pot. A well-known porous plug 12 is fitted on the bottom of the ladle 11, and an air supply pipe 13 for ejecting nitrogen gas is attached to the tip of the well, and nitrogen gas is vigorously injected into the hot metal from here. For this reason, the molten metal is in a boiling state (bubbling) and the reaction is performed violently.
The surface of the molten metal S gradually rises with the progress of the receiving of the molten metal, and when reaching the upper end of the ladle 11, only the molten slag S floating on the upper surface of the molten metal F spills from the end and is placed below the processing device 1. Flows into the inside of. The initial temperature of the molten slag S is 1000 ° C or more, which is almost the same as that of the hot metal, and it is a liquid with a reddish white color and high fluidity, but when it enters the processing apparatus 1, it touches the surrounding inner wall and cools rapidly. The temperature is lowered and accumulated. When an appropriate amount is accumulated and the temperature drops to an appropriate temperature, the air supply port 7 is opened and an appropriate amount of air is uniformly ejected from the porous plate 4 at the bottom.
Combustible gas, which is rapidly generated as the temperature drops, reacts violently with this jet gas to start the combustion phenomenon, and when the inflow of new slag from the top and the jet of air from the bottom are well balanced, This phenomenon is most pronounced and persistent.

For this balance, the blowing pressure and the flow rate of the compressed air must be well adjusted. As for the range of its spraying pressure and flow rate, the molten slag loses its retained heat by heat conduction to the surrounding refractory layer and solidifies, but it does not lead to agglomeration as a lump, but is in a boiling state as a powder. The requirement is that it be a fluid. The concept itself of powder boiling is
It is used in air flow type crushers. In other words, the object to be crushed is inserted into the casing, jetted from the surroundings evenly toward the center of the jet, and crushed by mutual friction between the objects to be pulverized. Induced by the vigorous movement of air bubbles, they violently flow, stir, and rub against each other. However, applying the concept of powder boiling to the treatment of slag is the most unique point of the present application, catching the time when solidification is occurring and the most flammable gas is actively generated, and air is evenly ejected from below. As a result, powder boiling is caused, and the contact with air is evenly distributed while preventing the formation of lumps of slag, and the low temperature combustion is completely completed.
This is an action that cannot be read from conventional similar techniques such as drawings.
The slag must be fully contacted with air in the treatment tank to completely gasify the poisonous and harmful gas source and completely burn it out. Therefore, the pressure and flow rate vary depending on the nozzle diameter and shape of the lower part of the container.Furthermore, when spraying is carried out especially inside the container, the shape and size of the combustion container and the relative positional relationship between the nozzle and the combustion container. There is also a difference, so it must be decided accordingly. For this purpose, the jet air pressure and the air amount required must be adjusted by adjusting the opening of the air flow rate adjusting valve 8 to maintain an optimum reaction. Considering that the lower limit of the desulfurization temperature at which calcium carbide and calcium phosphide can be completely eliminated is about 300 ° C. to 600 ° C., it is not necessary to heat the desulfurization slag with residual heat to a high temperature.

When the reaction has proceeded sufficiently, the molten slag has solidified and turned black, and the peculiar offensive odor has almost disappeared, a saucer (slot box, not shown) is placed at the bottom of the device, and the tubular body 2 and the hollow box 5 are placed. When the lock is released, the slag S in the tubular body slides down inside the wall and moves into the saucer (not shown), so that the whole slag is transported to a predetermined dump and processed. In this embodiment, since the hinges 6 are engaged with each other in the vertical direction, when the tubular body 2 is lifted, the hinges 6 are opened, the hollow box 5 is swung about this as a shaft, and the bottom is opened by itself. Becomes Further, as described above, since the surrounding refractory layer 3 and the hollow partition wall 9 are provided with the slope of the downward constriction, the sliding action of the slag S has a unique effect.

[Effects of the Invention] As described above, the present invention can significantly improve the working environment by simply receiving the molten slag from the ladle and treating it, and contribute to the health and safety of the worker. Naturally, it has no effect on the hot metal and its desulfurization treatment, and since it is sufficient to carry out incidental work that partially overlaps with the original continuous work procedure, it is also an advantage that it is easy to implement. .

[Brief description of drawings]

FIG. 1 is a front sectional view showing an embodiment of the present application, FIGS. 2A and 2B are front sectional views showing a conventional technique, and FIG. 3 is a front sectional view of a conventional technique. 1 ... Processing device, 2 ... Cylinder 3 ... Refractory layer, 4 ... Perforated plate 5 ... Hollow box, 7 ... Air inlet 8 ... Air flow control valve

Claims (2)

[Claims] 1. A molten pig iron which, when receiving a molten gun in a ladle, adds a de-ryuting agent from above the ladle and spouts an inert gas from the bottom of the ladle to separate and remove the resulting molten slag from the molten metal. In the desulfurization process, the molten slag was allowed to naturally flow down from the top end of the ladle into the processing tank immediately below, and the heat quantity of the flowing molten slag was cooled by the refractory tank on the side wall of the processing tank to 300- 600
In the temperature range above ℃, the controlled amount of compressed air is blown almost evenly from the bottom of the treatment tank so that the molten slag solidifies but does not condense into a lump and continuously maintains the powder state and continues the powder boiling.
A method for treating slag, characterized in that low-temperature combustion of a combustible gas contained in a powder is continuously maintained by the flow and contact of the air jet with the entire amount of the slag. 2. A hollow box 5 comprising a perforated plate 4 only on the upper surface of which is attached a refractory layer 3 on the side wall and is openable and closable around a hinge 6 as a fulcrum on the lower bottom surface of a cylindrical body 2 which spreads downward. A device for treating molten slag is characterized in that an air supply port for compressed air is attached to the side surface of 5 so that the air volume can be freely adjusted.