2.3 according to the 99.7% aluminium ingot supplier, the factors affecting the casting damage are as follows:
(1) liquid aluminum temperature;(2) contact strength between aluminum and oxygen;(3) aluminum slag aluminum content;(4) slag with the aluminum liquid;(5) the number of inferior aluminum, large aluminum;Other losses.
3. Ways to reduce casting damage
3.1 control the temperature of liquid aluminum
Aluminum strip, aluminum bar melting point is 660 ℃, generally aluminium casting temperature control at about 730 ℃, and even lower, and the corresponding casting Aluminum alloy has good liquidity temperature is lower than the original Aluminum, is about 710 ℃ to 730 ℃, for use in liquid Aluminum electrolytic cell unit directly, after the high temperature liquid Aluminum into the hybrid furnace, match into the cold material should be timely, to keep furnace add the defective goods Aluminum, Aluminum slag, etc., can also be part of the intermediate alloy (industrial silicon) in advance to join in furnace, molten state, formation pressure is increasing in yield and lower temperature.At the same time to join the cold material surface to clean can not have oil, or may burn heat to promote burning.In short, reducing the temperature of molten aluminum to the corresponding casting temperature can reduce the great influence of temperature on casting loss.
3.2 reduce the contact force between liquid aluminum and air. The greater the contact force between liquid aluminum and oxygen, the more serious the oxidation and burning loss and the greater the casting loss.
(1) to reduce the contact time between liquid aluminum and oxygen: (1) to meet the production requirements, as soon as possible, the furnace liquid aluminum into finished products, the best on duty ingredients on duty production, do not make the liquid aluminum in the furnace stay time is too long;(2) reasonable placement of the melting casting equipment, as far as possible to shorten the length of the flow tank, in order to reduce the exposure time of liquid aluminum in the air, at the same time, the upper part of the flow tank can be covered with aluminum silicate insulation board, both a certain insulation effect and can reduce the oxygen content in the flow tank.
In short, put an end to the aluminum liquid stored in the mixing furnace for a long time because of various reasons, in order to reduce the aluminum liquid and oxygen contact time to reduce the casting loss.
(2) control of liquid aluminum stirring mode: whether manual large rake stirring or mechanical stirring is carried out in the open state of the furnace door, which will not only bring huge fluctuation of liquid level, increase the contact area with oxygen and also increase the oxygen content of the furnace, it is bound to accelerate the chemical reaction and increase the burning loss.Electromagnetic stirring can be carried out in a closed state and the liquid level fluctuation is small, which effectively avoids the corresponding disadvantages. At the same time, it can also reduce the water in the air into the furnace, and reduce the absorption probability of liquid aluminum to hydrogen.
(3) control liquid aluminium refining bubble height: artificial directly to the general way of refining is refining agent and charging, then mixing refining, but for some alloy production to blow nitrogen refining (refining time longer, up to 30 minutes), there will always be certain of the froth height and transverse to the edge, at the end of shaft, drive the huge volatility of liquid aluminum, so it's best to adjust the nitrogen pressure, the froth height control in 10 to 15 mm.