[China Aluminum Network] In the process of aluminum alloy profile anodizing, the alkali corrosion is an important chemical corrosion treatment process to remove the natural oxide film and the profile of the surface of the minor scratches, so that the profile exposed uniform, fresh, Ideal appearance to facilitate anodizing of aluminum alloys.
Over time, the amount of aluminum hydroxide deposited in the alkaline pit increases. Sodium aluminate is not saturated with Al(OH)3 at supersaturated concentrations, but it is subject to the appearance of self-conscious differentiation under the influence of NaOH concentration, temperature, CO2, etc., and Al(OH)3 nucleus is then generated. Fine, with a particle size of 0.1 micron. Once Al(OH)3 nuclei are present in the solution, the hydrolysis of sodium metaaluminate (NaAlO2) is greatly accelerated.
The aluminium hydroxide initially separated is colloidal and gradually dehydrates under the effect of temperature and the agglomeration hardens, and these hard blocks also increase the temperature of the bath liquid. And this agglomeration is very strong in relation to the tank wall, and it usually takes 1 to 2 months to stop production and sort out once, which not only affects the production but also badly depletes sodium hydroxide and is not safe.
If you choose to remove the dissolved aluminum ions from the lye and then recover the lye, you can prevent the caking of the aluminum hydroxide in the lye, and then increase the output power. The recovered aluminum ions can also be reused, and the environmental protection is energy-saving.
Recovery methods include ion exchange method, dialysis method, water addition method, crystallization method, insoluble metal complex or salt separation method. The ion exchange resin method is economically unfavorable due to the large amount of disposal, and there is a certain difficulty in the dialysis method in the recovery process due to scale interference on the membrane surface. In the production, the crystallization method is mainly used for recovery.
Led Digital Kitchen Alarm Clock,Kitchen Timer,Digital Timer For Kitchen,Cooking Alarm Timer
Chengdu Augus Science Technology Co., Ltd. , https://www.vluckyaugus.com