China Nonferrous Metallurgy

The research topic is proposed on the basis of modern dry scrubbing technology for the treatment of fluoride-containing gas fume generated during aluminum electrolysis process. Two alumina samples are chosen as the absorbents for hydrogen fluoride gas in the laboratory adsorption experiments, respectively, one is a certain kind of domestic Bayer alumina while the other is a kind of alumina produced from coal fly ash. Firstly, a new setup of apparatus is designed and assembled to meet up the requirements for the static adsorption method for the investigation of hydrogen fluoride capacity on alumina. The influences of temperature and contact time on the adsorption process are carried out under 4 different temperatures of 25℃, 80℃, 95℃, 110℃ and 5 time intervals of 12min, 20min, 30min, 45min, 60min. The fluoride ion selective electrode method is employed for the determination of fluorine content in the reacted alumina, which is then used to calculate the average accumulated adsorption efficiency. Through the investigation of these two alumina samples, it is found that the adsorption capacity of hydrogen fluoride on the two kinds of alumina behaves slightly different. For the tested Bayer alumina, the adsorption rate under 110℃ is the fastest among all the tested temperatures in the early state of the adsorption process, the saturated adsorption capacity at 110℃ is 3.06g HF/100g Al₂O₃ While for the alumina manufactured from the coal fly ash, the fastest early stage adsorption rate appears at 95℃, and the saturated adsorption capacity at 95℃ reaches up to 2.94g HF/100g Al₂O₃.