Continuous casting process-12. Measures to prevent clogging of the nozzle
In the continuous casting production, in order to prevent the tundish nozzle from clogging, the following methods are used:
(1) Choose the appropriate nozzle material, such as joint boiler, quartz nozzle for low alloy copper or wrong quality nozzle, and aluminum cool water for aluminum-containing shed.
(2) Air washing nozzle, in which porous material is inserted around the inlet nozzle, and the surface air is blown into the inner wall of the nozzle to form a layer of gas film between the copper water and the nozzle wall to prevent the deposition of Al2O3. Argon pressure is 0.2~0, 3.5kg/c㎡, flow rate is 2~12L/min
(3) The tundish stopper rod blows hydrogen. Blow nitrogen into the center tube of the stopper to wash away the blockage on the inner wall of the nozzle. However, the European gas pressure and flow rate should be appropriate. If the flow rate is too large, the argon bubbles will cause the molten steel surface to churn, and the protection value slag will be involved in the molten steel and the inclusions will increase.
(4) Calcium treatment: Al2O3 is mixed in molten steel in star solid-state and clusters, which is the root cause of nozzle blockage. The denaturation treatment is used to transform the cluster-like solid Al2O3 into spherical liquid calcium aluminate to prevent water plugging. Calcium can prevent water plugging. For this reason, blow Si-Ca powder, feed calcium wire, or add Si-Ca alloy into the copper bag.
There is also nozzle heating, using CaO quality nozzle and changing the nozzle shape, etc., all have a certain effect on preventing the nozzle from clogging. But currently, the tundish stopper rod argon blowing and calcium treatment method are widely used.
Do you have any good methods please tell me, we would be very appreciated!
Daisy Zhai
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