铁尾矿陶粒的制备及其除磷性能研究

Preparation and phosphorus removal performance of iron tailings ceramsite

以铁尾矿为主要原料,粉煤灰为辅料,制备了铁尾矿陶粒,并通过原料配比实验和正交实验优化制备工艺参数。依据吸附等温模型、热力学参数和动力学模型拟合及XRD、SEM、FT-IR表征分析了铁尾矿陶粒对磷的吸附过程及吸附机理。结果表明,铁尾矿与粉煤灰质量比为9∶1,预热温度400℃、预热时间10 min、焙烧温度900℃及焙烧时间20 min时,制备得到的陶粒对磷的吸附率最高,达到了98.81%。Freundlich等温吸附模型和准一级反应动力学方程能更好地描述其吸附过程,铁尾矿陶粒对磷的吸附属于非均质表面的多层吸附,兼具物理扩散与化学吸附的特点,理论最大吸附量为1.68 mg/g;且铁尾矿陶粒对磷的吸附是一种自发的吸热过程。表征结果表明,铁尾矿陶粒表面粗糙,介孔结构丰富;主要晶体矿物为钙铝黄长石,吸附磷后有新的物相产生,附着在陶粒表面,并且多处波峰都有不同程度的减弱,推测铁尾矿陶粒对磷的吸附机理可能是表面的钙、镁等离子与磷酸盐反应生成Ca_(3)(PO_(4))_(2)等沉淀,并有羟基等离子与磷酸盐发生配体交换作用。

The iron tailings ceramsite was prepared with iron tailings as the main raw material and fly ash as the auxiliary material,and the technological parameters were optimized through the raw material ratio experiment and orthogonal experiment.Based on adsorption isothermal model,thermodynamic parameters,kinetic model,and XRD,SEM,FT-IR,the adsorption process and adsorption mechanism of phosphorus on iron tailings ceramsite were analyzed.The results showed that the highest phosphorus adsorption rate of 98.81%was obtained when the mass ratio of iron tailings to fly ash was 9∶1,the preheating temperature was 400℃,the preheating time was 10 min,the roasting temperature was 900℃and the roasting time was 20 min.Freundlich isothermal adsorption model and quasi-first-order kinetic equation could describe the adsorption behavior better,indicating that it belonged to the heterogeneous surface of multilayer adsorption,which was characterized by both physical diffusion and chemical adsorption,and the theoretical maximum adsorption capacity was 1.68 mg/g.The adsorption of phosphorus by iron tailings ceramsite was a spontaneous endothermic process.The characterization results showed that the surface of the iron tailings ceramsite was rough with rich mesoporous structure.The main crystal mineral was calcium-aluminum feldspar.After adsorption of phosphorus,a new phase was generated and attached to the surface of the ceramic particles,and the wave peaks in many places were weakened to different degrees.The adsorption mechanism of phosphorus by iron tailings ceramsite might be the sedimentation of Ca_(3)(PO_(4))_(2) produced by calcium and magnesium plasma with phosphate and other precipitates,and the exchange of ligands between hydroxyl plasma and phosphate.