Research of Lime-mediated Sewage Sludge Use as Metallurgy Sintering Ingredients in the Sinter Industry

摘要

This paper discusses the feasibility of the lime-mediated sewage sludge replace the fuels and flux as metallurgy ingredients, the influence of lime-mediated sewage sludge used in metallurgy sintering process to the sinter performance. The calorific value of the sludge was 4.67 MJ/kg. The X-ray diffraction (XRD) showed that the main existing form of Calcium in the lime-mediated sewage sludge is CaCO_3 at 550°C, and almost is CaO at 1100°C. This provided the basis to the sludge used as sintering ingredients. Sintering cup experiment results showed that Lime dry sludge have a positive impact on sintering, the sinter quality indexes are improved. When sludge ratio is 3.00%, the vertical sintering burning rate is 21.28 mm/min, the yield is 72.62%, the utilization coefficient is 1.455 T/m~2·h, fuel consumption from 65.65 kg/T fall to 59.16 kg/T, then concluded that the flux and fuel ratio replaced by lime-mediated sewage sludge were 43.3%, 13.3% respectively. The treatment and disposal of sewage sludge is an expensive and environmentally sensitive problem. It is also a growing problem worldwide since sludge production will continue to increase as new sewage treatment works are built and environmental quality standards become more stringent. Rich in a large number of organic matter in the sludge, pathogens, heavy metals, easy to cause the second pollution to the environment. In a variety of methods to Sludge dewatering, the Lime stabilization significantly reduce the advantages of moisture content which is efficient, economic and low operating cost can improve the storage and transportation conditions, avoid leachate leak at the same time, so it is widely used now. At present, the major outlets for lime-mediated sewage sludge are agriculture and landfill, with only a relatively small amount being incinerated. On the one hand, this occupies the land, on the other hand, this inevitable causes certain pollution to the environmental, this also wasted a lot of useful components in the sludge, the lime, organic matter, etc. This experiment adds the lime-mediated sewage sludge in an appropriate proportion to the high temperature of steel industry, dry sludge of principal components such as lime can be used as a flux, organic matter can be used as a fuel, the sludge after lime process still has certain moisture, it can reduce the amount of moisture in sintering ingredients, and the direct use of water in lime dry sludge can reduce the time of sludge drying and the sludge treatment time, realize the high value-added use of effective ingredients in sludge.