将属危险废物的含砷石膏转化为一般废物的工艺研究

发布时间：2018-04-20 06:32

  本文选题：含砷石膏 + 稳定化　； 参考：《广西大学》2015年硕士论文

【摘要】：本文对砷的性质、含砷石膏的来源、污染和治理进行了综合论述。以硫酸厂的含砷石膏和实验室自制的高砷含量石膏为研究对象,采用加温转晶稳定化和药剂稳定化两种方法对其进行稳定化处理,并对稳定化效果进行检测和比较。实验采用正交实验和单因素实验设计方法考察各因素对稳定化效果的影响规律,参照HJ/T299-2007固体废弃物浸出毒性浸出方法,检测含砷石膏的稳定化效果。采用硫酸硝酸水平振荡法对其进行浸出性能研究,为属危险废物(下称危废)的含砷石膏的危害性评估、无害化处理提供基础数据。经毒性浸出实验数据显示,处理前砷含量分别为1.3%、2.8%、5.8%和7.2%的含砷石膏,其砷的毒性浸出浓度依次为8.0 mg·L-1、12.0 mg·L-1、25.6 mg.L-1和52.5 mg.L-1,均大于5 mg.L-1(一般废物的浸出毒性砷浓度限值),表明处理前含砷石膏均为危险废物。稳定化处理后含砷石膏的砷的毒性浸出浓度显著降低。对于晶型转化法,在处理时间为5 h时,优化的转晶温度分别为140℃、140℃、200℃和250℃进行转晶稳定化处理。经处理后的含砷石膏浸出毒性砷浓度分别为4.1 mg·L-1、4.25 mg·L-1、3.9 mg·L-1和4.5 mg.L-1。使属危废的含砷石膏转变成稳定的一般固体废物。铁盐稳定化试验中,铁砷摩尔比是影响稳定化效果的主要因素。在反应时间为15 mmin,温度为30℃,pH为6.86,为达到较好的稳定化效果,处理砷含量分别为1.3%、2.8%、5.8%和7.2%的含砷石膏,所需的硫酸铁的优化铁砷摩尔比分别为1、1、2.5和3,处理后四种含砷石膏浸出毒性砷浓度依次为1.27 mg·L-1、4.23 mg·L-1、4.1 mg·L-1和7.2 mg.L-1。聚合硫酸铁的优化铁砷摩尔比分别为1、1、2和2.5,处理后四种含砷石膏浸出毒性砷浓度依次为1.13 mg·L-1、1.23 mg·L-1、3.3 mg·L-1和3.78 mg.L-1。由浸出毒性的结果可知,砷含量在6%以下的含砷石膏,砷含量愈高稳定化时所需的铁砷摩尔比愈高。但砷含量再高的时候,再用硫酸铁作为稳定剂进行稳定化处理时,就不能达到理想效果了。而聚合硫酸铁均可以使砷含量在1-7%的含砷石膏转化为一般废物。转晶稳定化和铁盐稳定化均可作为含砷石膏稳定化的方法,但转晶稳定化时间长,温度高,操作复杂,而铁盐稳定化的反应时间短,反应速度快,工艺相对来说更容易实现工业化。
[Abstract]:The properties, sources, pollution and treatment of arsenic-containing gypsum are discussed in this paper. Taking arsenic gypsum in sulphuric acid plant and gypsum with high arsenic content in laboratory as the research object, the stabilization treatment was carried out by using two methods of temperature-changing crystallization stabilization and medicament stabilization, and the stabilization effect was tested and compared. The effects of various factors on stabilization effect were investigated by orthogonal experiment and single factor experimental design. The stabilization effect of arsenic-containing gypsum was detected by referring to HJ/T299-2007 solid waste leaching toxicity leaching method. The leaching performance of sulfuric acid nitric acid horizontal oscillation method is studied, which provides basic data for hazard assessment and innocuous treatment of arsenic-containing gypsum belonging to hazardous waste (hereinafter referred to as hazardous waste). The experimental data of toxic leaching showed that the arsenic content before treatment was 1.32.8wt% and 7.2% arsenic-containing gypsum, respectively. The toxic leaching concentration of arsenic was 8.0 mg / L ~ (-1) 12.0 mg / L ~ (-1) 25.6 mg.L-1 and 52.5 mg 路L ~ (-1) respectively, both of which were higher than 5 mg 路L ~ (-1) (the limit value of arsenic concentration was 5 mg 路L ~ (-1)), which indicated that arsenic-containing gypsum was hazardous waste before treatment. The toxic leaching concentration of arsenic in arsenic gypsum decreased significantly after stabilization treatment. For the method of crystal transformation, when the treatment time is 5 h, the optimized transgranular temperature is 140 鈩，

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