The cementitious activity of chromium residue and the effect of different dosage of chromium residue on the physical properties of Portland cement were studied in this paper. And the influences and the control of different kinds of mineral additions were experimented through adding the zeolite, fly ash and blast furnace slag powder into the chromium－cement system. The results of this study shows that the chromium residue has good cementitious activity, and Cr(Ⅵ) concentrations in the leachate is decreased very much by adding the slag powder in the chromium－cement  system.

Activating of fly ash, in the different admixtures and temperatures, had been studied by the methods of TGA, XRD,pore structure  and TSC－TG analysis. Especially, the stability of Mullite structure of fly ash was studied. Results show that erosion of alkali on the Mullite is weak although in the alkali surrounding, so when activation of fly ash was studied, the influence of Mullite can be ignored.

The paper introduces the electrotatic precipitators are selected and used for the collection of powdered hemihydrate phosphogypsum and dedust to clean kiln gas from phosphogypsum－calcined section, after drying the phosphogypsum. The propertics of media (cement kiln gas and tail gas ), and the necessity , operation parameters and selection of specifition of the electrostatic precipitater with dew point factors, corrosion of equipment, creepage , as well as the determination of insulator and elimination of thermal collapse are discussed.