How to we remove Si in HPA

Si impurities are difficult to remove due to inactivity. Qi Guangxia et al. reacted fly ash with sodium hydroxide solution at a constant temperature of 130℃ for 1 h, and predeactivated fly ash, with an efficiency of 30.0%. Sun Yinglong et al. studied the effects of mass fraction of sodium hydroxide, ash/alkali ratio, reaction time and reaction temperature on the desorption efficiency through orthogonal experiments. The results showed that the effects of time, alkali solution concentration, ash/alkali ratio and reaction temperature on the desorption efficiency were enhanced successively, and the desorption efficiency reached 38.6% under the optimal conditions. Dong Fei et al. comprehensively used the core technologies of pre-de-SI and alkali lime sintering, and put forward valuable Suggestions on the application of de-SI process equipment.
We believe that the impurities Si and Fe in the samples will be exposed after roasting, and then the ultrasonic wave is used to repeatedly pickling and washing them, and the final content of Aluminum hydroxide Si and Fe is less than 0.001%. It is recommended to filter the raw materials with activated carbon column or micro-porous titanium membrane to remove impurities. Lai Jun on the sodium aluminate solution in the process of preparation of high purity alumina Si and Fe impurity removal was studied, using calcium oxide as desilication agent, to react with water to produce the calcium hydroxide, calcium hydroxide and sodium aluminate reaction tricalcium aluminate, silicate ion reacts with the tricalcium aluminate generation of refractory hydrated garnet, precipitation in the form of precipitation, finally to take off the Si rate can reach 98%. In addition, the power plant USES aluminum hydroxide adsorption, reverse osmosis, micro-bubble flotation, electrical coagulation and other Si impurities removal.
In the above methods, some impurity elements such as Na and Ca will be introduced, and some are suitable for the removal of trace Si, but not suitable for the deep removal of trace Si. Therefore, it is very necessary to study a method for the effective removal of trace Si.