Because of the many impurities in the molten aluminum in the electrolytic cell, the aluminum ingot must be filtered prior to the casting of aluminum ingots, commonly used methods, solvents, gases and clarification of the purge method.

The following briefly describes the solvent purification method and gas purification method:

1, solvent purification method is to use the solvent added to the solution, the solvent has a small density, high activity, strong adsorption and other characteristics. By adsorbing oxides in the solution, new droplets form to the surface. Scum formed after cooling. Aluminum ingots can be cast to remove scum.

2, gas purification, commonly used **, nitrogen or ** mixed gas, is a major primary aluminum purification method.

(1)** Purification. The introduction of aluminum into the liquid leads to the formation of many small bubbles, which are fully mixed in the liquid of aluminum, and the dissolved hydrogen therein, as well as some mechanical inclusions, can be adsorbed on the small bubbles. As the bubbles rise to the surface of the aluminum liquid, they are discharged.

(2) Nitrogen purification method. Because ** is toxic and costly, nitrogen purification occurs. Alumina balls (418 mm) were used as the filter media. N2 directly into the liquid aluminum. The molten aluminum is continuously fed into the purifier, passes through the alumina ball filter, and is flushed with nitrogen. The non-metallic inclusions and dissolved hydrogen in the molten aluminum are then removed and continuously discharged, so that the fine nitrogen bubbles are evenly distributed. In the treatment of aluminum liquid play a role in purification.

(3) Mixed gas purification method. A mixture of ** and nitrogen is used to purify the aluminum liquid. Its role is to remove hydrogen and separate oxides on the one hand, and to remove certain metal impurities (such as magnesium) on aluminum. The commonly used composition is 90% nitrogen + 10%* *. There are also 10%** +10% carbon dioxide + 80% nitrogen. This works better, carbon dioxide can make ** and nitrogen well spread, can shorten the operation time.

Enterprises should choose the appropriate purification method based on actual needs.