控制硫酸铜加入量实现脱硫废水回用的初步研究

以Na2CO3-NaHCO3缓冲溶液为吸收液的湿法氧化脱硫技术所形成的脱硫废液,含有大量的Na2SO4、Na2S2O3、NaSCN,导致脱硫效率降低且严重超出污水排放标准,成为生产和环保的难题。提出在脱硫废液中加入适量硫酸铜,当硫酸铜的加入量为废液中NaSCN含量的50%左右时,可形成物相纯净的CuSCN沉淀,同时水体中S2O32-转化为SO42-,而且未检测出溶液中有残余的铜离子。经过该法处理过的水体中SCN-、S2O32-浓度显著降低,SO42-浓度增加接近饱和浓度值,再采用低温结晶法析出部分Na2SO4后可作为脱硫液补水回用。

Pilot study on the recycling of desulfurization wastewater by controlling the addition amount of copper sulfate

The desulfurization wastewater formed by wet oxidation desulfurization process,which had used NaHCO3-Na2CO3 buffer solution as absorption liquid,consists of lots of oxidation by-products,such as Na2SO4,Na2S2O3 and NaSCN.However,its desulfurization efficiency was low and seriously exceeded the discharge standard of wastewater,resulting in difficult problems in its production and environmental protection.It is suggested that adequate copper sulfate should be added to the desulfurization wastewater.When the added amount of copper sulfate is about 50% of sodium thiocyanate content in the wastewater,and the precipitation of CuSCN in pure phase can thus be obtained.At the same time,S2O32-in the water body can be converted into SO42-.Moreover,the remaining Cu2+ is under detective limit.The concentrations of SCN-and S2O32-in the water body which have been treated by this method gets lower obviously,and the concentration of SO42-gets higher,nearly to its saturation value.Furthermore,after part of Na2SO4 is separated out by low temperature crystallization process,the water body can be reused as compensating water for the desulfurization wastewater.