煤系废物地聚合物稳定/固化重金属离子效果研究

Effect of research on geopolymer based on coal waste for stabilization/solidification of heavy metals

基于传统地聚合物的硅铝质原材料的单一性和局限性限制了地聚合固化技术处置重金属离子的发展,因此,本文研究了煤系废物地聚合物稳定/固化重金属离子的性能.采用活性煤系废物代替常用的低钙粉煤灰、偏高岭土,以碱激发,研究制备了一种新型、高性能无机地聚合物,并对比分析了重金属离子(Co2+、Cr3+、Zn2+、Ni2+)的稳定/固化效果.结果表明,常温(20℃)、相对湿度95%时,煤系废物地聚合物的最佳配比为:煤矸石和粉煤灰的质量比m(G)∶m(CFA)=7∶3、微硅灰质量分数7%,无定形地聚合物凝胶紧密包裹在粉煤灰和煤矸石颗粒周围,固化体表面出现大量鱼鳞片状产物,层层交织,结构体致密.综合固化体抗压强度和浸出毒性的标准,Co2+、Cr3+、Zn2+、Ni2+的理想固化量分别为1.5%、2.5%、2.0%、1.5%,固化效果明显,稳定性良好,长期安全性.

The singleness and limitations of traditional geopolymers restricts the development of the immobilization of heavy metals by Silica-Aluminum raw materials. In this study, performance and mechanism of geopolymer prepared by coal waste for stabilization / solidification of heavy metals were investigated. The commonly used low-calcium fly ash and metakaolin were substituted by coal waste to produce the new geopolymer by alkali-activate technology,and comparative analysis on the effect of heavy metals stability / curing was conducted. Results showed that with room temperature of 20 ℃ and the relative humidity of 95%,the optimized ratio between activated coal gangue and high-calcium fly ash was reached as 7 ∶ 3,with mixture of 7% microsilica fume. The gangue and fly ash are closely surrounded by amorphous polymers. The formation of plenty scaly products upon the surface of solidifying object make the structure more dense,and the layers of the structure are mutual intertexture. Considering the compressive strength and the leaching toxicity,the optimum addition amounts of Co2 +,Cr3 +,Zn2 +and Ni2 +are 1. 5%,2. 5%,2. 0% and 1. 5%,respectively. The immobilization is effective and has good stability and long-term safety.