低浓度二氧化硫二转二吸工艺的设计与实践

从热平衡角度对φ（SO2）为4．5％的金精矿酸化焙烧烟气采用二转二吸工艺制酸的可行性进行分析，确认系统有可能实现自热平衡。由于供矿的原因，该金精矿酸化焙烧制酸装置需要在烟气φ（SO2）4．5％与8％之间切换运行，切换周期为10天以上。设计采用了“3＋2”ⅢⅠ—ⅤⅣⅡ流程，并设置了适当的副线，以便于调节各段进口温度。装置投运后转化系统实现了自热平衡，总转化率达99．8％。

Design and practice of double contact sulphuric acid process using Iow-SO2 off-gas

Whether a sulphric acid plant with 4. 5% SO2 off-gas from acidifying roasting of gold concentrate could adopt double contact process is analyzed in term of thermal balance and the answer is YES. Due to ore supply, the plant would operate with the off-gas of which SO2 concentration swings between 4. 5% and 8% in an interval of more than 10 days. The plant was designed with＂3 ＋2＂ ⅢⅠ-ⅤⅣⅡ process and proper bypasses for conveniently adjusting inlet temperature of each catalyst bed. After start, the plant operated smoothly and autothermally with a total conversion of 99.8%.