The pozzolanic activity of four types of ceramic wastes such as ceramic tiles wastes， porcelain wastes， stoneware wastes and pottery flowerpot wastes were investigated by means of XRD， determination of glassy phase， the  28days compressive strength ratio and pozzolanic activity， respectively， which will be helpful to the application of ceramic wastes． The experimental results showed that ceramic polishing powder and ceramic tiles wastes has the similar component but the former type of wastes was limited to application of cement admixture because of the high chloride concentration． Four types of ceramic wastes have good pozzolanic activity， and their 28 days compressive strength ratio were higher than 62％ ．The compressive strength ratio of the polished ceramic tiles wastes， porcelain wastes， the stoneware wastes and the pottery flowerpot wastes was 82.1％， 80.8％， 78.3％ and 77.3％， respectively, which has the same order of content of glass phase. The polished ceramic tiles wastes which contains the highest content of glass phase has the highest 28 day compressive strength ratio．

HN-1 and HN-2 alkali slag cement retarder is developed based on hydration mechanism of alkali slag cement． The effect of different addition on setting time and strength is explained by the author． Testing results show that HN-1 and HN-2 can extent the setting time of alkali slag cement． When adding less retarder in the cement, the compressed strength of paste and bending strength of mortar can be improved than without adding retarder． But the compressed strength will be reduced if adding more retarder．

Problems produced from raw meal measuring on calcium carbide sludge is discussed in here． Matrix effect on measuring result is analyzed and corresponding resolving method is presented in this paper． Comparison is made also on the practical samples under different testing conditions．

Impact factors on dust removal efficiency are analyzed on cyclone filter． Improvement measures are pointed out for increasing dust removal efficiency．