Abstract: In order to realize the harmless and resource utilization of river sediment,the sediment ceramsite was prepared by high temperature sintering using river sediment as the main raw material and bentonite,starch and limestone as auxiliary materials.Through single factor experiment,the influence of bentonite,starch and limestone dosage on the properties of ceramsite was discussed,and the raw material ratio and roasting process of ceramsite were optimized by orthogonal test.At the same time,the phase composition and microstructure of the ceramsite were studied by XRD and SEM analysis.The results showed that the optimal ratio of raw materials was the mass ratio of sediment,bentonite,starch and limestone of 70∶30∶10∶13,and the process conditions were preheating temperature of 400 ℃,preheating time of 10 min,roasting temperature of 1 000 ℃,roasting time of 15 min.Under the conditions,the bulk density of ceramsite was 725.52 kg/m³,the apparent density was 1 326 kg/m³,the water absorption rate was 25.00%,the compressive strength was 3.32 MPa,and the phosphorus removal rate was 98.69%.Sediment ceramsite has rough surface,rich pore structure,good water absorption and permeability,and high phosphorus removal rate,which could be used as ceramsite filter material in water treatment.

Key words: river sediment,ceramsite,single factor experiment,orthogonal experiment,roasting