亚熔盐法粉煤灰脱铝渣水热处理后碱含量的影响因素

以亚熔盐法处理粉煤灰的脱铝渣为原料，采用动态水热法分解脱碱，研究了不同A/S(Al2O3/SiO2质量比)、C/S(CaO/SiO2质量比)和不同脱铝溶出工艺对硅渣碱含量的影响. 结果表明，随脱铝渣A/S增加，碱含量先降低后升高，脱铝渣A/S为0.11，硅渣Na2O含量降至1.18%，适当的A/S有利于提高硅渣中含铝托贝莫来石的晶化程度；脱铝渣C/S为0.98，硅渣Na2O含量仅有1.31%，随脱铝渣C/S增加，硅渣碱含量增加，C/S过高会降低硅酸钠钙(NaCaHSiO4)的分解率，不利于生成含铝托贝莫来石相；溶出时间和停留时间较长的脱铝渣在脱碱过程中不易生成含铝托贝莫来石.

Influential Factors of Alkaline Content in Alumina-removed Residue by Hydrothermal Treatment from Extraction Process of Alumina from Fly Ash with Sub-molten Salt Method

Aluminum-removed residue from in the exaction process of alumina from fly ash by sub-molten salt method was decomposed to recover sodium by dynamic hydrothermal method. The effects of mass ratio Al2O3 to SiO2 (A/S), mass ratio of CaO to SiO2 (C/S) and dissolution processes of aluminum-removed residue on the alkaline content in final silicate residue were examined. The results indicate that the sodium content decreases first and then increases with the increase of A/S, the sodium content in the silicate residue is as low as 1.28% when A/S is 0.11, appropriate A/S can help improve the crystallization degree of Al-substituted tobermorite in the silicate residue. The sodium content in the silicate residue is only 1.31% when C/S is 0.98, the sodium content decreases with the increase of C/S, and the decomposition rate of NaCaHSiO4 decreases at high C/S, which is not beneficial to formation of Al-substituted tobermorite. The aluminum-removed residue with longer dissolution time and residence time is not easy to generate Al-substituted tobermorite in the sodium removal process and causes the increase of sodium content in the final silicate residue.