疏浚底泥-大理石废粉陶粒的制备工艺及性能

Preparation and performance ofdredged sediment-marble waste powder ceramsite

通过对两河段底泥(DSⅠ和DSⅡ)、大理石废粉(MWP)两种固体废弃物的化学组成及热稳定性分析,确定制陶原材料配比与工艺参数范围,设计了以不同原料配比、预热时间、焙烧温度、焙烧时间为因素,以堆积密度、吸水率、抗压强度和除磷率为水平的正交实验,并根据正交实验结果分别确定了一种制备高强建筑轻集料(DMC-HC)和一种高效除磷滤料(DMC-HP)的最佳原料配比和工艺参数,利用XRD观察不同性能的DMC物相变化,分析DMC抗压性能与除磷性能的形成过程。结果表明,底泥与大理石废粉能够很好地制备陶粒,在原料配比为DSⅠ∶DSⅡ∶MWP=2∶1∶0.8、预热时间为10 min、焙烧温度为1060℃、焙烧时间为10 min时,可制得堆积密度为696.29 kg/m3,表观密度为1430 kg/m3,空隙率为52.23%,吸水率为33.42%,抗压强度为2.37 MPa,破碎率于磨损率之和为4.12%,盐酸可溶率为1.56%,比表面积为2.06 m2/g的高效除磷陶粒;DSⅠ∶DSⅡ∶MWP=2∶1∶0.8、预热时间为5 min、焙烧温度为1180℃、焙烧时间为15 min时,制得堆积密度为950.35 kg/m3、吸水率为1.5%、抗压强度为25.53 MPa的低吸水率、轻质高强陶粒。结合XRD物相分析表明:陶粒主要通过化学沉淀达到高效除磷效果,在1180℃时形成的蓝晶石和铝酸钙是使陶粒获得高强性能的主要原因。

Based on the analysis of chemical composition and thermal stability of sediment(DSⅠand DSⅡ)in two river section and marble waste powder(DWP),the range of ceramsite processing parameters was determined.The effects of different ceramsite raw material ratio,preheating time,calcining temperature and calcining time on the bulk density,water absorption,compressive strength and phosphorus removal rate of sediment-marble waste powder ceramsite(DMC)were studied by orthogonal experiment.The phase change of DMC with different properties was observed by XRD,and the formation mechanism of DMC performance was analyzed.The results show that:DSⅠ∶DSⅡ∶MWP=2∶1∶0.8,preheating time is 10 min,calcining temperature is 1060℃,calcining time is 10min,the lightweight-high efficient phosphorus removal ceramsite with bulk density of 696.29 kg/m3,water absorption rate of 33.42%,compressive strength of 2.37 MPa and phosphorus removal rate of 99.81%can be obtained;When DSⅠ∶DSⅡ∶MWP=2∶1∶0.8,preheating time is 5 min,calcining temperature is 1180℃,calcining time is 15 min,low water absorption and lightweight-high strength ceramsite with bulk density of 950.35 kg/m3,water absorption of 1.78%and compressive strength of 16.7 MPa are prepared.Combined with XRD phase analysis,the results show that the high-efficiency phosphorus removal effect of ceramsite is mainly achieved by chemical precipitation.Kyanite and calcium aluminate formed at 1180℃are the main reasons for the high-strength performance of ceramsite.