Degassing Unit for Molten Aluminum Casting Process

01 3月 Degassing Unit

Posted at 03:05h in Aluminium Degassing by admin 0 Comments

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Degassing Unit is installed between the furnace and the casting machine to eliminate hydrogen and other residues contained in the molten aluminum and its alloys that affect its quality and mechanical properties.
It has an ultra-long life furnace body using a new high-silicon molten material manufacturing technology. The degassing rotor, heater protection sleeve, and thermocouple protection sleeve all use silicon nitride (Si3N4) ceramic manufacturing technology and produce high added value , The production technology of aluminum products with high technical performance requirements.

Degassing Unit

AdTech Degassing Unit consists of the following parts
Mechanical transmission
Box cover
Rotor and heater
Electrical control

Degassing Unit

Degassing Unit performance
On-line degassing equipment mainly processes molten aluminum that contains a certain amount of hydrogen and other residues (alkali metals, slag inclusions), which are removed after being processed by degassing equipment.
The processing principle of the online degassing equipment is the principle of gas flotation. The process gas (inert gas or a mixture of inert gas and chlorine gas) is injected into the melt through the rotor and broken into uniformly dispersed tiny bubbles by the rotor, and the tiny bubbles rise to the melt. On the surface, when the tiny bubbles rise, the following tasks are completed:
Hydrogen is absorbed into the bubble and is eliminated;
Alkali metals are eliminated by chemical interaction with chlorine gas (formation of chloride);
The inclusions are trapped by bubbles and then rise to the surface of the melt to form dross.

Degassing Unit

Instructions for Degassing Unit
When the oven is finished, the heating element is turned off before the molten aluminum enters the box. When the temperature of the heater is close to the temperature of the molten aluminum, inert gas is introduced into the rotor, and then the molten aluminum is filled into the box.

Check the sealing material at the junction of the inlet and outlet and the runner.
Check the tight plug of the bottom drain port with high temperature protection
Check whether the molten aluminum temperature of the filling tank is high enough (minimum temperature: 720°C). In order to observe the molten aluminum entering the tank, stop the filling operation at a position about 3 cm away from the bottom of the launder.
The box cover is closed (the box has a slag raking port). The operator must wear a proper protective jacket. When the metal flows into the box, scum is generated, and the scum on the metal surface can be skimmed through the slag raking port.
It is recommended that the temperature rise to above 780 degrees to reproduce, start the temperature holding stage, and close the slagging port.
During the heat preservation phase, the molten aluminum between the castings is allowed to remain in the box at the temperature set by the operator.
The molten aluminum is not processed during this holding stage.
A small amount of inert gas needs to be introduced into the rotor to prevent molten aluminum from entering the rotor and blocking the air outlet of the rotor.
After the molten metal stops filling operation, the heater needs to be started immediately, and the heating is controlled according to the metal insulation parameters, which is set by the operator.
By starting the heating system to control the temperature of the molten aluminum, it is necessary to monitor the gas flow rate, the rotor speed increases, and the speed is changed from the heat preservation stage to the speed set in the treatment stage, and the inert gas flow into the rotor increases, from the heat preservation stage to the treatment stage flow.
The operator sets the temperature of the molten aluminum in the processing stage and heats in this mode to achieve a stable degassing working state.