摘要
对煤粉锅炉粉煤灰(FA1灰)和循环流化床锅炉粉煤灰(FA2灰)采用湿法磁选的工艺达到降低其重金属含量的目的.利用扫描电子显微镜、激光粒度仪和X射线衍射仪表征两种粉煤灰在不同磁感应强度和不同磁选溶液浓度条件下磁选前后高磁性和弱磁性部分的形貌、粒度分布和物相分析,同时测定其铁元素和5种重金属元素(Hg、Pb、As、Cr、Cd)的含量变化,发现磁选后两种粉煤灰铁回收率随着磁感应强度增强而逐渐增加,高磁性组中重金属元素含量与弱磁性组有明显差异.结果 表明:在磁感应强度为8000 Gs和磁选溶液浓度为20%(质量分数)时,FA1的铁回收率为71.2%,FA2的铁回收率为47.0%.此时FA1磁选后Pb含量差值为0.2 mg/kg、Cr含量差值为9.2 mg/kg、As含量差值为1.1 mg/kg;FA2磁选后Pb含量差值为18.1 mg/kg、Cr含量差值为25.0 mg/kg、As含量差值为9.1 mg/kg.
Abstract
A wet magnetic separation process was used for pulverized coal boiler fly ash(FA1 ash)and circulating fluidized bed boiler fly ash(FA2 ash)to reduce their heavy metal content.Scanning electron microscope,laser particle sizer and X-ray diffractometer were used to characterize the morphology,particle size distribution and physical phase analysis of the highly magnetic and weakly magnetic parts of the two types of fly ash before and after magnetic separation under the condi-tions of different magnetic induction strengths and different concentrations of magnetic separation solutions,and to deter-mine the changes in the contents of iron and five heavy metal elements(Hg,Pb,As,Cr,Cd).It was found that the iron recov-ery rate of the two types of fly ash after magnetic separation was increased gradually with the increase of magnetic induction strength,and the content of heavy metal elements in the high magnetic group was significantly different from that in the weak magnetic group.The results showed that the Fe recovery of FA1 was 71.2%and that of FA2 was 47.0%at the magnetic induction intensity of 8000 Gs and the magnetic separation solution concentration of 20%.At this time,the difference of Pb content,Cr content and As content after magnetic separation of FA1 was 0.2 mg/kg,9.2 mg/kg and 1.1 mg/kg,respectively.The difference of Pb content,Cr content and As content after magnetic separation of FA2 was 18.1 mg/kg,25.0 mg/kg and 9.1 mg/kg,respectively.
基金项目
宁夏回族自治区重点研发计划(2022BDE02001)
银川市科技计划(2022ZDGX11)
维普
万方数据