Phenomenon analysis of failure of argon blowing of ladle permeable bricks and how to improve the rate of argon blowing

Argon blowing is usually to build one or several breathable bricks at the bottom of the pouring ladle or brick ladle. After tapping, argon is blown into the ladle to cause agitation of the molten steel in the ladle. Floating up can partially remove the gas dissolved in the steel and the uniform components. In the case of continuous casting, the ladle blowing argon can adjust the temperature of the molten steel. The ladle blowing argon is an important steelmaking process, and the breathable brick is the It is an important functional element of the process. It is of great practical significance to study the performance, loss mechanism and use management of breathable bricks to improve the blowing rate and the quality of molten steel.

Phenomenon Analysis of Argon Blowing Failure of Ladle Breathable Bricks

The argon gas pipeline is leaking or the gas permeable brick sleeve is leaking, so that the argon gas cannot pass into the refining ladle normally. When this happens, the argon gas flow rate displayed on the argon gas flow meter is very large, but the molten steel level of the ladle is not high. Very calm or small fluctuations, and the effect of argon stirring is almost invisible. The end face of the breathable brick is blocked by cold steel, cold slag, garbage, or the air channel is blocked by steel infiltration, resulting in argon gas blocking. This situation is shown as: blowing argon At the beginning, the oxygen supply flow of the argon gas flow meter was large, and then gradually became smaller, and the pointer fell to zero. The argon gas pipeline was broken and leaked in the middle of the refining process, so that the argon gas could not pass into the ladle. The flow of argon gas displayed on the gas flow meter increased, but the pressure indication on the pressure gauge after the pressure reducing valve was zero.

Measures to improve the rate of ladle blowing with argon

Improve the masonry process. Observe and check the ventilation bricks before repairing the tank. It is stipulated that the working surface of the ventilation bricks is not lower than 30mm from the bottom of the tank to prevent cold steel; check whether the metal hose is burnt out and whether the screws at the two ends are loose. Treatment. In order to ensure the strength of argon blowing and reduce the infiltration and blockage of molten steel, use a feeler gauge to check the air passage of the breathable brick slit before masonry, and select a breathable brick with an air passage width suitable for the working conditions; before masonry, check whether the tail pipe thread of the breathable brick is Damaged. Make sure that the tail pipe does not enter the dust and debris during the process of building the breathable brick. After the ladle is repaired, the garbage at the head of the breathable brick should be cleaned up.

It is better to use the breathable bricks with longer lifespan and less steel penetration in the airway under certain working conditions.

Careful use. During the use of the breathable brick, strictly control the flow of argon gas at different processing stages to avoid the erosion of the bottom-blown breathable brick with a large flow of bottom blowing. The gas should be treated immediately to prevent gas leakage, which will reduce the pressure in the pipeline and cause the bottom blowing failure.

strengthenLadle breathable brickMaintenance. Because the concave part is easy to solidify the steel after the bottom blowing permeable brick is eroded, it is stipulated that after the steel is poured, the gas source (argon or compressed air) should be connected to the large ladle turntable immediately, and the infiltrated steel and the bottom of the air channel that have not yet solidified are blown out. Blow the accumulated steel in the recessed part of the breathable brick. After the ladle is turned over and the slag is poured, lift it to the hot repair area and put it down, and then connect the quick connector to test the flow rate of the breathable brick with compressed air or argon. Pull out the quick connector without any treatment or minor treatment; if the flow rate cannot meet the requirements, use oxygen-burning backflushing measures. The residual cold steel cold slag on the working face shall be used until the flow rate of the permeable brick meets the requirements. On the premise of ensuring that the flow rate and blowing rate of the permeable brick meet the requirements, oxygen burning for a long time should be avoided as far as possible. The distance between them is kept at about 50mm. The closer the distance is, the longer the oxygen burning time will be, which will accelerate the melting loss of the working surface of the breathable brick, thereby artificially reducing the service life of the breathable brick.

In order to prevent molten steel from penetrating into the air-permeable brick due to positive pressure during the stop of argon blowing, install reverse osmosis devices on the argon blowing pipeline—one-way stop valve, air bag, etc. Set an alarm at 150mm from the lower part of the air-permeable brick core In order to ensure the safe use of the breathable bricks, it can be used to a certain extent, reduce the leakage accident of the breathable bricks caused by the ladle inspection error, and enable the breathable bricks to be replaced regularly. Dynamic management of the breathable bricks, masonry, Each link of use, inspection, backflushing, backburning, testing, and dismantling should be recorded in detail so that problems can be found in time.

The purity of the argon gas used for argon blowing and stirring of the ladle should be 99.99%, and its content should be strictly controlled below the specified 8ppm. When the argon gas with a serious oxygen content exceeds the standard, when it passes through the working face of the permeable brick, the oxygen is fluxed on the working face of the permeable brick. It will accelerate the high temperature melting loss of the breathable brick, which will generally reduce the life of the breathable brick, and in severe cases will lead to a steel leakage accident of the breathable brick.