摘要
燃煤锅炉烟气湿法脱硫废水中的重金属及钙镁等离子危害较大,开展其沉淀去除规律的研究有利于废水中有用元素的资源化回收和废水的回用。采用碱液沉淀法对脱硫废水进行分级处理,对沉淀产物采用SEM-EDS等手段进行表征。结果表明,采用氢氧化钙作为沉淀剂可以实现去除重金属、回收镁资源及去除氟化物和降低废水硬度等多种目标。在去除重金属离子的过程中,当脱硫废水pH值为9.0~9.5时,废水中的重金属离子可得到有效去除且达到污水排放标准,镁离子几乎没有损失,钙增加率也较低,仅为4.6%以下;将废水pH值调整为9.5~9.7可有效回收废水中的镁元素,镁的回收率在62%以上,回收效果较好。在碱性条件下,向废水中投加Na_(2)CO_(3)可有效降低废水中的钙离子和残留的镁离子,实现废水降硬的目标。不同pH值下沉淀物的SEM-EDS能谱显示,对脱硫废水进行梯级pH处理可以达到分级去除重金属污染物和回收镁元素的目标。通过对脱硫废水中重金属及钙镁结垢离子的沉淀规律研究,实现了废水的分质分盐有用成分的资源化回用,避免了产生杂盐危废造成二次污染的可能,达到了脱硫废水的零排放的目标。
The heavy metals and calcium-magnesium ions in the wastewater of flue gas wet desulfurization of coal-fired boilers are harmful.The study of precipitation and removal law is beneficial to the recovery of useful elements and the reuse of wastewater.The paper used alkaline precipitation method to classify desulfurization wastewater for treatment,and the precipitation products were characterized by SEM-EDS.The results show that the removal of heavy metals,recovery of magnesium resources,removal of fluoride and reduction of wastewater hardness can be achieved by using Ca(OH)2 as precipitator.In the process of removing heavy metal ions,when the pH value of desulphurization wastewater is 9.0~9.5,the heavy metal ions in the wastewater can be effectively removed and meet the discharge standard.Magnesium ions have almost no loss,and the calcium increase rate is also relatively low,only below 4.6%.Adjusting the pH value of the wastewater to 9.5~9.7 can effectively recover the magnesium element in the wastewater,the recovery rate of magnesium is above 62%,the recovery effect is better.Under the alkaline condition,adding Na_(2)CO_(3) into the wastewater can effectively reduce the calcium ions and residual magnesium ions in the wastewater and achieve the goal of reducing wastewater hardness.The SEM-EDS spectra of precipitates at different pH values show that the removal of heavy metal pollutants and recovery of magnesium element can be achieved by staged pH treatment of desulphurization wastewater.By studying the precipitation law of heavy metals and calcium-magnesium scaling ions in desulphurization wastewater,the reuse of useful components of separating and separating salts in wastewater was realized,and the possibility of secondary pollution caused by dangerous waste of miscellaneous salts was avoided,the target of zero discharge of desulphurization wastewater was achieved.
作者
王志永
崔振
赵德玉
勾宝亮
刘树弟
李兰廷
寇丽红
刘敏
张显学
王亚强
Wang Zhiyong;Cui Zhen;Zhao Deyu;Gou Baoliang;Liu Shudi;Li Lanting;Kou Lihong;Liu Min;Zhang Xianxue;Wang Yaqiang(Tangshan Zhongrun Coal Chemical Co.,Ltd.,Tangshan 031501,China;Kailuan(Group)Limited Liability Corporation,Tangshan 031500,China;China Coal Research Institute,Beijing 100013,China;Key Laboratory of National Energy Coal Efficient Utilization and Energy Conservation and Emission Reduction Technology and Equipment,Beijing 100013,China)
出处
《能源与环保》
2024年第3期155-161,共7页
CHINA ENERGY AND ENVIRONMENTAL PROTECTION
基金
开滦(集团)有限责任公司科技创新计划科技攻关项目(XZ2022-23)。
关键词
脱硫废水
碱液沉淀
重金属离子
钙镁离子
desulphurization wastewater
alkali precipitation
heavy metal ions
calcium and magnesium ions
