Aluminum liquid burning loss refers to the process from the beginning of the injection of aluminum liquid into the mixing furnace to the end of the casting process, under high temperature conditions through mechanical or manual stirring, slag, so that aluminum liquid oxidation, and with the oxidation of slag is stripped out of the non-recoverable loss.

The main factors affecting the oxidation loss of aluminum liquid are: aluminum liquid temperature, aluminum liquid oxygen content and aluminum liquid and air contact time. Aluminum liquid burning loss includes two parts: mixed furnace burning loss and casting process burning loss.

Influencing Factors of Aluminum Liquid Burning Loss in 2.1 Mixing Furnace

The main factors affecting the formation of oxides in molten aluminum are temperature, turbulence and available oxygen. Generally, the temperature of the aluminum liquid obtained from the aluminum electrolysis cell is about 900 ℃ ~ 950 ℃. At this temperature, the oxidation rate of aluminum may be 10 times that of the aluminum liquid at the casting temperature (the typical casting temperature is 700 ℃ ~ 750 ℃); Another influencing factor is turbulence, which provides a fresh molten surface source for oxide formation. At high temperatures, oxides are formed extremely rapidly on these fresh surfaces, and the relationship curve between the amount of oxides formed and time is a typical parabola, and the most prominent process of aluminum liquid burning is the use of lifting bags to pour into the mixing furnace. It is pointed out that the high temperature and the turbulence caused by the small waterfall are the root causes of the large amount of scum in the mixing furnace. From the actual situation of aluminum liquid casting in Dongxing Aluminum Company, there are many factors causing aluminum liquid burning loss.

2.1.1 The temperature of the molten aluminum from the electrolysis workshop is too high.

The melting point of aluminum is 660 ℃, the temperature of the raw aluminum liquid sucked into the vacuum lift from the aluminum electrolytic cell is about 900 ℃ ~ 950 ℃, the temperature of the aluminum liquid is about 850 ℃ when it is injected into the mixing furnace, and the pouring temperature is controlled at 700 ℃ ~ 750 ℃. There is a temperature difference of about 100 ℃ ~ 150 ℃ between the aluminum liquid temperature and the pouring temperature in the mixing furnace. And such a large temperature difference causes aluminum liquid suction and burning loss.

2.1.2 Aluminum liquid in the mixing furnace for too long, so that the amount of aluminum liquid suction increased.

The oxygen inhaled directly oxidizes the aluminum liquid, and the water vapor inhaled in the process can also dissociate the oxygen atom to oxidize the aluminum liquid. 2.1.3 The solid cold materials added into the mixing furnace are not clean, and contain oil stains, residual asbestos, silt, etc., which accelerate the oxidation of aluminum liquid. Experience has proved that whether the furnace charge is clean before entering the furnace has a very different effect on the production of oxidized slag. The reason is that unclean burden, oil dirt, etc., are likely to burn and release heat at high temperatures, which will promote smelting and burning. At present, the aluminum liquid casting workshop of Dongxing Aluminum Company does not deal with industrial waste such as oily aluminum chips and waste asbestos boards, and has not put forward clear regulations to the post personnel. There is a situation that industrial waste is mixed into aluminum blocks in the recycled furnace, thus deteriorating the cleanliness of aluminum liquid and increasing the burning loss of aluminum liquid in the mixed furnace.