湿堆磷石膏渣场黏土防渗层效果分析

EFFECTIVENESS OF CLAY LINER IN SEEPAGE CONTROL FOR WET PHOSPHOGYPSUM STACKS

大规模磷石膏堆存一般使用水力填充的方法,即采用湿堆磷石膏渣场。我国大多数现存湿堆磷石膏渣场均采用黏土底垫层作为防渗层。通过对磷石膏渣场中酸性水的渗漏速率与渣场高度、磷石膏的渗透特征、黏土防渗层厚度以及黏土渗透系数的关系进行分析。结果表明:由于湿堆磷石膏渣场黏土防渗层上部无渗沥液收集层,即使黏土垫层达到了一般工业固废填埋场防渗标准的要求,湿堆磷石膏渣场的酸性工艺水渗漏量仍将远超过相同占地面积的一般工业固废填埋场。在黏土垫层下部存在碳酸盐岩层的情况下,从磷石膏渣场中渗漏的酸水还可能导致溶洞的出现和发展,进而导致黏土防渗层的塌陷和酸性工艺水的大规模渗漏,最终造成更为严重的环境污染。

Wet stacking is by far the most popular disposal method for large-scale phosphogypsum disposal.Most phosphogypsum disposal facilities in China use clay liner to minimize downward seepage of acidic water into the environment.This paper shows that the volume of leacheate from a wet phosphogypsum stack is related to the stack height,permeability of phosphogypsum,thickness and permeability of clay liner,and can be dozens of times greater than that from a solid waste disposal facility with the same compacted clay liner due to the lack of a leacheate collection layer above the clay liner within the wet gypsum stack.If the underlying formation below the clay liner is carbonate rocks,the leakage of acidic water can result in the occurrence and development of sinkholes,which may lead to collapse of the clay liner and serious pollution to the environment.