水化石榴石对赤泥基地聚物形成过程的影响研究

Effect of Hydrogarnet on the Formation of Geopolymer in Red Mud

拜耳法赤泥是铝硅酸盐矿物为主的碱性混合物,是制备地聚物材料的潜在原料。以高温拜耳法赤泥的主要成分水化石榴石为原料制备了地聚物材料,并分析了其强度形成及固碱机理。研究表明,水化石榴石经焙烧、碱激发可制备以水化聚硅铝酸盐(Ca-PS、Na-PS)、水化铝酸钙(C3AH6)为主的钙基地聚物,其形成可分为三个步骤:高温下水化石榴石发生Al-O链断裂,分解成钙基铝酸盐、聚铝硅酸盐;在水玻璃的激发下,聚铝硅酸钙中Al-O链断裂,形成正硅铝酸钙的水化物并释放出氢氧化铝;铝酸钙、氢氧化铝、氢氧化钙与自由的硅酸根离子、钠离子反应生成聚硅铝酸钙、聚硅铝酸钠的水化物,并排除剩余的水分,固结硬化成地聚物材料。钠离子在地聚物的形成过程中进入结构被固定下来,可以有效抑制赤泥基材料的泛碱。

Bayer red mud is an alkaline mixture dominated by aluminosilicate minerals and a potential raw material for the preparation of geopolymer materials. The geopolymer material was prepared from hydrogarnet, which is the main component of red mud by Bayer process at high temperature, and its strength formation and alkali fixation mechanism were analyzed. The results show that calcium based polymer, with polyaluminosilicates(Ca-PS、Na-PS) and hydrated calcium aluminate(C3 AH6) as the main components, can be prepared by calcination and alkali excitation of hydrogarnet. The formation can be divided into three steps: the Al-O chain in hydrogarnet breaks down into calcium aluminates and calcium aluminosilicates at high temperature. The Al-O chain in calcium aluminosilicate breaks under the excitation of sodium silicate, forming hydrated calcium aluminate and releasing aluminum hydroxide. Calcium aluminate, aluminum hydroxide and calcium hydroxide react with free silicate ions and sodium ions to form polyaluminosilicates hydrate, and with the remaining water being excreted, resulting in the consolidation and hardening of the geopolymer material. Sodium ions enter the structure are fixed during the formation of geopolymer, which can effectively inhibit the efforescence of red mud-based geopolymer.