Based on some key elements of acid rain in Guangdong area, the slags of two types and two sizes are leached from sulphuric acid mill at Yunfu pyrite area, west-Guangdong, in order to observe the thallium leaching-out in the slags.

This paper introduces technics process of dry discharging system after reformation of "W"type flame boiler bottom residue in Huaneng Shang an Power Plant,points out the technology advantages of device reformation,analyze the economy and society benefit after reformation.