Contamination and prevention of drying waste gas during processing municipal sewage sludge in the cement kiln were investigated, utilizing HAPSITE portable gas chromatograph/mass spectrometer and N(1-naphty1)-ethylene diamine dihydrochloride spectrophotometric method to measure the waste gas composition. The results show that, offensive odor off-gases are produced from the municipal sewage sludge with a high moisture content during the drying process, the composition of which includes ammonia, hydrogen sulfide, aromatic compounds, halohydrocarbon and so on and the direct emission of which contaminates the environment. The waste gas, from sewage sludge drying using the fresh hot air, can combust with pulverized coal at 950℃, which not only leads to the decomposition of several harmful components in the waste gas but also reduces the NOx concentration. The approach to directly dry the sludge with kiln back-end waste gas is questionable. It is suggested that the hot gas from cement rotary kiln shell cooling or the clinker cooler is recovered and used to dry sewage sludge, following which the waste gas enters the kiln for combustion.

In the exploitation of oil and gas, H2S/CO2 in the layer of earth causes carbonized corrosion to cement-stone, seriously affecting the cementing result. To improve the corrosion-resistant properties of cement-stone in the acid medium and basing on the analysis of corrosion mechanism of cement-stone in the presence of H2S and CO2 in this paper, it is experimentally proved that micro-silica is a kind of good fillers which increases the density of cement-stone and therefore enhances its compressive strength. Corrosion was performed on the cement-stone at different ages and the compressive strength was tested after the corrosion. The corrosion-resistant properties of pure cement and micro-silica-added cement were compared. Meanwhile, metallurgical microscope and X-ray diffraction were used to analyze the corrosion-resistant reasons after the addition of micro-silica.