Technology of molten steel drying and physical drying
Date：2020-09-27 / Hits：394
Part I molten steel drying
1、 Preparation before oven:
1. The surrounding of the steel pot must be welded with the furnace surface with scrap steel bars (6 ~ 8 pieces are appropriate), so as to prevent the steel pot from sinking after falling and causing sand falling down;
2. 2-3 tons of solid small heavy materials are added into the furnace, and the furnace charge should be solid and even, which can prevent molten steel from scouring the bottom of the furnace;
3. Check if the water pressure of intermediate frequency furnace is 1.5 ~ 2kg and the hydraulic pressure is normal.
2、 Start up, warm up:
1. The function of the oven is to dry the moisture of the furnace charge and reduce the temperature difference between the molten steel and the furnace body;
2. The oven time is generally 5 hours, and the medium frequency voltage is about 100V ~ 280v, which can be operated according to the heating curve;
3、 After the oven is finished, add molten steel:
1. Cut off the medium frequency power supply before adding molten steel;
2. The sliding nozzle is used to inject molten steel. When injecting molten steel, the operator should keep away from the furnace mouth as far as possible, so as to avoid spraying steel when the furnace air is compressed;
3. If the surface of molten steel is frozen, blow open the frozen furnace surface by blowing oxygen to avoid the expansion of furnace air.
4、 Heat preservation
After the injection of molten steel, the temperature of molten steel should be slowly raised to 1680 ~ 1700 ℃, then the steel should be heated for 2 hours, and the medium frequency voltage is about 450 ~ 500V.
5、 Tapping
After tapping, the condition of the whole furnace body should be checked, and then the second furnace should be fed to produce sintering layer.
Part II physical oven
1. Material selection
Operating principle: the higher the carbon content, the lower the melting point;
The middle part of medium frequency furnace belongs to high temperature area, and the upper part and lower part belong to low temperature area;
Avoid empty burning caused by the burden is not solid.
According to the above principle, since the steel pot is relatively high in carbon content and easy to cut, the steel pot should be welded on the furnace surface. If the steel pot wall is thin, vertical tie bars should be used, and 14-16 round steel and 4-5 screw steel bars should be vertically welded on the inner wall. Two thirds of pig iron and high chromium, or solid small and heavy materials such as cutting head and tail are required for furnace burden. In this way, empty burning can be prevented, and the melting point of steel pot will be close to it, without causing furnace collapse. It is forbidden to use light and thin materials, such as shavings and thin steel pipes, as raw materials for the oven.
2. Blanking
First, two thirds of the furnace's pig iron, cutting head, tail and other solid small and heavy materials, cooperate with the intermediate frequency furnace operator to turn on the intermediate frequency machine. Before starting the intermediate frequency machine, who should pay attention to, whether there is 1.5 ~ 2kg, and whether the hydraulic pressure is normal.
3. Heating up
The principle of temperature rising is that the moisture in the furnace charge is the main factor when the temperature is 0 ~ 900 ℃.
When the temperature is between 900 ℃ and 1350 ℃, the burden begins to soften until it melts slowly, and the furnace wall forms sintered crystals with the molten steel.
When the temperature is between 1350 ℃ and 1600 ℃, the sintered layer and semi sintered layer are formed completely.
When the temperature is 1680 ~ 1700 ℃, the thickness of sintering layer is increased and the working strength of sintering layer is enhanced.
The temperature should be raised slowly in the whole drying process, and it should not be heated rapidly.
4. Oven time
The whole time is 16-20 hours. In the first 12 hours, the medium frequency voltage is 200-300v, which remains stable. After drying the moisture in the furnace charge, the medium frequency voltage can be increased by 100V every 1 hour. When the steel is hydrated to four fifths of the furnace, the power can be maximized. After the molten steel is melted, the temperature is raised to 1680 ~ 1700 ℃ for two hours, and the medium frequency voltage is between 450 ~ 500V The art is finished.
Attached table: oven drying curve
1、 Preparation before oven:
1. The surrounding of the steel pot must be welded with the furnace surface with scrap steel bars (6 ~ 8 pieces are appropriate), so as to prevent the steel pot from sinking after falling and causing sand falling down;
2. 2-3 tons of solid small heavy materials are added into the furnace, and the furnace charge should be solid and even, which can prevent molten steel from scouring the bottom of the furnace;
3. Check if the water pressure of intermediate frequency furnace is 1.5 ~ 2kg and the hydraulic pressure is normal.
2、 Start up, warm up:
1. The function of the oven is to dry the moisture of the furnace charge and reduce the temperature difference between the molten steel and the furnace body;
2. The oven time is generally 5 hours, and the medium frequency voltage is about 100V ~ 280v, which can be operated according to the heating curve;
3、 After the oven is finished, add molten steel:
1. Cut off the medium frequency power supply before adding molten steel;
2. The sliding nozzle is used to inject molten steel. When injecting molten steel, the operator should keep away from the furnace mouth as far as possible, so as to avoid spraying steel when the furnace air is compressed;
3. If the surface of molten steel is frozen, blow open the frozen furnace surface by blowing oxygen to avoid the expansion of furnace air.
4、 Heat preservation
After the injection of molten steel, the temperature of molten steel should be slowly raised to 1680 ~ 1700 ℃, then the steel should be heated for 2 hours, and the medium frequency voltage is about 450 ~ 500V.
5、 Tapping
After tapping, the condition of the whole furnace body should be checked, and then the second furnace should be fed to produce sintering layer.
Part II physical oven
1. Material selection
Operating principle: the higher the carbon content, the lower the melting point;
The middle part of medium frequency furnace belongs to high temperature area, and the upper part and lower part belong to low temperature area;
Avoid empty burning caused by the burden is not solid.
According to the above principle, since the steel pot is relatively high in carbon content and easy to cut, the steel pot should be welded on the furnace surface. If the steel pot wall is thin, vertical tie bars should be used, and 14-16 round steel and 4-5 screw steel bars should be vertically welded on the inner wall. Two thirds of pig iron and high chromium, or solid small and heavy materials such as cutting head and tail are required for furnace burden. In this way, empty burning can be prevented, and the melting point of steel pot will be close to it, without causing furnace collapse. It is forbidden to use light and thin materials, such as shavings and thin steel pipes, as raw materials for the oven.
2. Blanking
First, two thirds of the furnace's pig iron, cutting head, tail and other solid small and heavy materials, cooperate with the intermediate frequency furnace operator to turn on the intermediate frequency machine. Before starting the intermediate frequency machine, who should pay attention to, whether there is 1.5 ~ 2kg, and whether the hydraulic pressure is normal.
3. Heating up
The principle of temperature rising is that the moisture in the furnace charge is the main factor when the temperature is 0 ~ 900 ℃.
When the temperature is between 900 ℃ and 1350 ℃, the burden begins to soften until it melts slowly, and the furnace wall forms sintered crystals with the molten steel.
When the temperature is between 1350 ℃ and 1600 ℃, the sintered layer and semi sintered layer are formed completely.
When the temperature is 1680 ~ 1700 ℃, the thickness of sintering layer is increased and the working strength of sintering layer is enhanced.
The temperature should be raised slowly in the whole drying process, and it should not be heated rapidly.
4. Oven time
The whole time is 16-20 hours. In the first 12 hours, the medium frequency voltage is 200-300v, which remains stable. After drying the moisture in the furnace charge, the medium frequency voltage can be increased by 100V every 1 hour. When the steel is hydrated to four fifths of the furnace, the power can be maximized. After the molten steel is melted, the temperature is raised to 1680 ~ 1700 ℃ for two hours, and the medium frequency voltage is between 450 ~ 500V The art is finished.
Attached table: oven drying curve