Experimental Researchon Strengthened Dehydration Technology Of Silicium Calcium Slag

Being the secondary product of producing alumina from high-alumina fly ash, silicium-calcium slag becomes a superior raw material for cement production because of its various advantages, including high reactivity, low sintering temperature, energy conservation, good clinker quality and large slag-using amount. However, due to the complicated dissolution reaction during the alumina production process, the great influence of uncontrollability of secondary reaction results in the high water content and concentration of silicium-calcium slag slurry, which makes the filtering separation of silicium-calcium slag slurry the bottle-neck of silicium-calcium slag application.The present study is aimed at lowering the water content of post-separation filter cake by exploring the filtering separation technique of silicium-calcium slag slurry. For this purpose, flocculation settling pretreatment and strengthened dewatering of silicium-calcium slag wereemployed. Based on the basic physical properties analysis of silicium-calcium slag, the flocculation settling pretreatment of silicium-calcium slag was investigated, and the results showed that the best flocculant is cationic etherified starch, and its best addition amount is 0.02%. The investigation of filtering separation revealed that pressurized filtration could yield filter cakes with the lowest water content, and the best filtering pressure was 0.3 MPa. Particle granularity between 0.125~0.075 mm was found beneficial to the dewatering of post-separation filter cakes. Out of five types of surface active agent, the dodecyl trimethyl ammonium chloride surface active agent with the addition amount of 0.75% was found best for the dewatering of silicium-calcium slag.Based on the above investigation, the filtering separation technology of silicium-calcium slag was determined. The water content of silicium-calcium slag filter cakes can be lowered to around 40% by pretreatment and strengthened dewatering.The results of this study provide theoretical basis and experimental proof of the technology of strengthened dewatering of silicium-calcium slag for industrial production.