镍冶炼烟气制酸的酸性废水减排及再利用

Reduction and recycle of acidic waste water from sulphuric acid plant based on nickel smelting off-gas

分析镍冶炼烟气制酸净化系统酸性废水的产生机理及酸浓度分布特点,并在此基础上改进了工艺。分别从净化系统洗涤塔抽出含酸泥废水,从间冷器和电除雾器抽出高酸度废水;除去酸泥并回收有价金属后,水返回净化系统循环使用,w(H2SO4)20%的稀酸作为补充水用于干吸系统配酸。为配合工艺需要,开发并采用了无中和酸性废水脱泥技术、高效速渗污泥干化池及混酸技术。装置运行效果良好,充分实现了废水减排和资源再利用。

Formation mechanism and acid concentration profile characteristic of acidic waste water from cleaning system of sulphuric acid plants based on nickel smelting off-gas were analyzed and process improvements were carried out. Slag-laden acidic waste water was drawn from scrubbing tower and high-acidity waste water was drawn from indirect cooler and wet electrostatic precipitator, respectively. After removing slag and recovering valuable metals, water was recycled into cleaning section and weak acid at 20 wt% H2SO4 was used as make-up water for acid concentration adjusting in drying and absorption section. To meet the requirement of process, a neutralization-free acidic water de-slag technology, high-efficiency and fast permeation drying pool and acid mixing technique were developed and used. The plant was operating satisfactorily and reduction of waste water discharging and resource reuse were achieved to the full.