The apparent phenomenon of zinc ash is the formation of strip or point inclusions along the longitudinal direction of the fine slag belt on the surface of aluminum zinc plate, which is a slight defect, but the frequency of occurrence is higher than other
The formation reason is that the zinc ash is produced by the dross on the zinc surface at the furnace nose and the solid zinc slag condensed in the inner cavity of the furnace nose. The zinc slag falls on the surface of the strip steel and produces slight
linear indentation along with the strip steel passing through the sink roll of the zinc pot, or the fine slag belt forms strip or point inclusions along the longitudinal direction on the surface of the aluminized zinc plate, resulting in zinc ash defects.
Cause of formation of gray and zinc plated aluminum plate
The control measures are as follows:
1. Optimization of nitrogen humidification system for furnace nose
The humidification system can raise the dew point temperature and make
the zinc vapor form a protective film on the surface of liquid zinc to inhibit the continuous evaporation of liquid zinc. If the dew point temperature is not controlled properly, too much steam may produce defects. Therefore, the best dew point temperature
of the furnace nose should be determined in practice.
2. Cleaning of zinc slag in furnace nose
1) Make special slag scoop and clean the scum in the furnace nose 2-3 times per shift.
2) The zinc slag adsorption and removal device in the
furnace nose is added, and the external hot air is blown into the closed furnace nose through the fan.
3) Use the downtime to reduce the zinc pot, expose the zinc liquid level at the furnace nose, and then remove the slag manually.
control of strip steel entering boiler
Strictly control the temperature of the strip into the zinc pot, because the temperature of the strip exceeds 20 ℃ of the liquid zinc, not only the temperature of the zinc pot will be increased, but also the
quantity of zinc slag will be increased.