油页岩循环流化床锅炉底渣和飞灰中重金属元素浸出毒性研究

为了研究我国桦甸油页岩65 t/h循环流化床锅炉的底渣和飞灰中重金属元素Cr、Cu、Pb和Zn的赋存状态及不同酸度条件下的浸出特性,分别进行了逐级提取实验和分批浸出的淋滤实验。逐级提取实验结果表明,这4种元素在底渣和飞灰中具有基本相当的赋存状态。硫化物结合态和稳定的残渣态是各元素的主要赋存状态,元素的潜在浸出能力大小表现为:PbCrCuZn,飞灰中各元素的潜在浸出能力大于底渣中的。浸出实验结果表明,元素的赋存状态决定了其浸提能力,浸提液的pH值对各元素浸出能力的影响不尽相同,各元素的浸出能力随浸提时间的延长都会趋于平衡,Cr和Pb的浸出浓度都高于地表水和饮用水的国家标准。

Study on heavy metals leaching toxicity of fly ash and bottom slag

The mode of the occurrence and the leaching characteristics of heavy metals Cr, Cu, Pb and Zn in bottom slag and fly ash of oil shale from circulating fluidized bed boiler of 65 t/h were investigated using sequential chemical extraction and leaching experiment. The results of sequential chemical extraction study indicated that heavy metals had similar content and occurrence in bottom slag and fly ash. Heavy metals mainly existed in sulfide and residue states. The potential leaching capacity of the elements were: Pb>Cr>Cu>Zn, moreover, the heavy metals in fly ash were higher than that in bottom slag. The results of leaching study indicated that the occurrence of elements was decisive for leaching capacity. pH of leaching solution had dissimilar effect on elements leaching characteristics. The leaching capacities of Cr and Pb exceeded the national standard for surface water and drinking water.