Research On Preparation Of Lightweight Ceramsite By Using Silt

With the development of industry and agriculture and the accelerating of urbanization in our country,industrial wastewater,municipal wastewater,livestock wastewater and various kinds of rubbish leachate have been released into the rivers in various forms,which caused the pollution of most rivers is increasingly serious,resulting in the amount of polluted river silt is also in-creasing.River silt contains various toxic substances,including heavy metals.It will not only cause further deterioration of water pollution and harmness of benthos through the secondary release of harmful substances,but also can cause land pollution when the cleared silt was im-proper disposed.At the same time,the production of shells is increasing year by year with the development of coastal marine aquaculture.But the utilization approach of shells is limited cur-rently,as a result,the accumulation of a large number of discarded shells not only pollutes the surrounding environment,but also bothers people's life.The chemical composition of silt is sim-ilar to clay,and the main component of the shells is calcium carbonate.Therefore,the task of searching for utilization ways of silt and shell is urgent.Using silt and shell to prepare light-weight ceramic is a highly feasible resource approach.In this issue,using silt as the main raw material,shell and clay as secondary raw materials prepares lightweight ceramsite by burning expansion method.Combining conclusions of single factor experiments and orthogonal experiment,the best ratio of raw materials and the best ce-ramic preparation conditions can be selected,with the apparent density and water absorption of ceramsite as indexes.Using scanning electron microscopy(SEM)characterizes microstructure structure of ceramsite.Modify ceramsite using ferric chloride as modifier and determine the op-timal modification conditions,with the removal ratio of modified ceramsite on methylene blue solution as index.Use modified ceramsite adsorb organics and NH3-N in wastewater and inves-tigate the effect of ceramic dosage and contact time on the adsorption effect.The results showed that when the ceramsite preparing raw materials ratio of shell pow-der:silt:clay is 40%:45%:15%,calcining temperature is 1150?,calcining time is 45-minute,the ceramic have best performances that the apparent density is 1.08g/cm3,water absorption is 38.6%,the weight wear rate is 1.43%,the average particle diameter of ceramsite is 4.4mm,the bulk density is 0.57g/cm3,the compressive strength is 3.1MPa.The ceramsite has better curing effect on heavy metals and metals leaching rate is lower.The best ceramic calcining conditions can be selected when silt is used as the only raw materials.They are as follows:the calcining temperature is 1150?,calcining time is 45-minute.In this condition,the apparent density is 1.83g/cm3,the water absorption is 16.5%,the wear rate is 0.03%,the average particle diameter of ceransite is 4.4mm,the bulk deIsity is 0.921 g/cm3,the compressive strength is 4.2MPa.Modifing the silt,clay and shell powder mixed ceramsite using ferric chloride as modifier,the best modified conditions can be selected that the calcining temperature is 600 ?,calcining time is 2-hour,the concentration of modifier ferric chloride is 2mol/L,with the removal ratio of mod-ified ceramsite on methylene blue solution as evaluation index.The removal rate of modified ceramsite on methylene blue can reach 86.5 percent,which is about two times of unmodified ceramsite's.Using modified ceramsite adsorb organics and NH3-N in wastewater showed that the extension of reaction time and increase in amount of ceramsite both can make a better adsorption effect.Using river silt and shell powder as raw materials to prepare light ceramsite has good eco-nomic,environmental and social benefits.It solves the river silt disposal problem and abandoned shells flooding problem in the coastal area,the ceramsite has obtained good effect in water treatment at the same time.