石煤提钒尾渣基钙长石烧结砖的烧结及重金属固化机理

Sintering and Heavy Metal Solidification Mechanism of Anorthite Building Sintered Brick from Stone Coal Tailings After Vanadium Extraction

这是一篇陶瓷及复合材料领域的论文。石煤提钒尾渣是一种危险的工业废弃物,综合利用石煤提钒尾渣具有重要的环保与经济意义。本研究以石煤提钒尾渣为主要原料制备了建筑用烧结砖,研究了烧成温度对样品结构和性能的影响规律,探究了Cu、V和Zn重金属浸出活性的钝化机理。结果表明:烧成温度显著影响烧结砖的相组成、显微结构和性能。适当提高烧成温度不仅有助于石英与原料中的碱性物质反应,生成富硅液相,提高样品的致密度,而且促进了黄长石向钙长石转变及莫来石生成。这些晶相与玻璃相互胶结,赋予制品较高的致密度和抗压强度。此外,提高烧成温度增大了制品中Cu、V和Zn的残渣态含量,减小了制品的孔径与孔容积,从而实现了Cu、V和Zn的固化。采用烧成温度为1 200℃,保温时间为3 h的工艺制度,制备出的建筑用烧结砖的各项性能均满足《烧结普通砖》(GB/T 5101—2003)中Mu25等级的要求,且制品的Cu、V、Zn重金属浸出浓度均低于标准值。研究结果为石煤提钒尾渣的综合利用提供了新的思路。

This is an article in the field of ceramics and composites.Vanadium extraction tailing from stone coal is a dangerous industrial waste.Comprehensive utilization of vanadium extraction tailings from stone coal has important environmental and economic significance.The fired bricks for building were prepared from the vanadium extraction tailings of stone coal.The effects of firing temperature on microstructure and properties were studied,and the leaching activity passivation mechanism of Cu,V,and Zn heavy metal was explored.The results showed that sintering temperature significantly affected the phase composition,microstructure and performances of sintered bricks.Properly increasing the firing temperature was not only in favour of silicon-rich liquid phase generation to increase the density of samples by the reaction between quartz and alkaline element in raw materials,but also contributed to anorthite transformation from melilite and the mullite formation.These crystalline phases bond with glass,endowing the product with high density and compressive strength.In addition,an increase in firing temperature improved the Cu,V,and Zn residual content in the product,reduced the pore size and volume,thus achieving the solidification of Cu,V,and Zn.With the 1150℃firing temperature and 3 h holding time,the properties of the sintered building bricks can meet the requirements of standard Mu25 in《fired common bricks》(GB/T5101-2003).Cu,V,and Zn leaching concentrations in the product were below the standard values.This study provides a new insight for the efficient utilization of vanadium tailings from stone coal.