Integrated technology of electrolytic aluminum flue gas desulfurization, defluorination and dust removal

Regarding SO in the flue gas of the aluminum industry₂To meet the need for simultaneous treatment with fluoride, a series of key technologies and equipment for flue gas treatment from carbon product production, alumina production to aluminum electrolysis have been developed. At the same time, key technologies for defluorination in the desulfurization process have been researched and developed. The defluorination products, cryolite and alumina, are filtered and recovered together, and sent to the electrolytic aluminum plant for recycling. The desulfurization process directly produces fertilizer ammonium sulfate, achieving the goal of flue gas desulfurization₂Integrate and recycle fluoride treatment.

Solved the problem of fluoride ion absorption and enrichment in the flue gas of wet flue gas desulfurization in the aluminum industry, and achieved SO in the flue gas₂Integrated with fluoride treatment, while recovering sulfur and fluoride resources. After gas treatment, the SO2 emission concentration is less than 50mg/Nm³、 F - Emission concentration below 1mg/Nm³.

scope of application

Purification of Fluorine containing Flue Gas in Aluminum Electrolysis

Main technical content

1、 Basic principles

Using aluminum electrolysis production raw material - alumina as adsorbent, fluoride (mainly hydrogen fluoride) in flue gas as adsorbate, under set conditions (including solid gas ratio in the reaction section, reaction time, flue gas flow rate, etc.), alumina is mixed with hydrogen fluoride to complete the adsorption of hydrogen fluoride in a very short time and achieve high purification efficiency.

Firstly, aluminum oxide with relatively poor activity and adsorbed hydrogen fluoride (also known as fluorine loaded aluminum oxide) is used to undergo a secondary adsorption reaction on the remaining hydrogen fluoride in the initial flue gas of aluminum electrolysis with high fluorine concentration using the first high activity aluminum oxide, in order to obtain a higher fluorine purification efficiency.

The reverse two-stage dry adsorption purification technology optimizes the dry adsorption mechanism and achieves extremely high fluorine purification efficiency with a lower solid to gas ratio in the reaction section, thereby reducing the number of cycles of alumina in dry adsorption and avoiding the problems of high alumina crushing rate, increased FE and SI impurities introduced, and high power consumption in the aluminum electrolysis flue gas purification system caused by multiple cycles.

2、 Technical key

In the dry adsorption purification of aluminum electrolysis flue gas, firstly, reverse two-stage adsorption is adopted to fully utilize the adsorption capacity of hydrogen fluoride. Then, fresh alumina is added to the second stage to adsorb the remaining hydrogen fluoride in the flue gas again, thereby increasing the "driving force" of the purification process; This technology optimizes the dry adsorption mechanism, increases the fluorine load of alumina, and effectively reduces the amount of adsorbent used; In the selection of dust collectors for aluminum electrolysis flue gas purification systems, more attention is paid to low resistance and high efficiency. This technology uses an improved low-pressure pulse long bag dust collector and aluminum electrolysis flue gas purification special filter material - JZL-D fine filter needle felt, to achieve international advanced dust removal efficiency.

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