MgO含量变化对污泥陶粒性能的影响

Effect of MgO concentration on the characteristics of lightweight aggregate made from sewage sludge and river sediment

以污水污泥和河道底泥为原料,采用高温烧制的方法制备陶粒。主要考察了污泥底泥原料中MgO含量变化对陶粒性能的影响。研究表明,MgO含量在1.2%～3%时,制备的陶粒物理性能优良,符合污水处理滤料的要求;MgO含量为1.5%时,陶粒表面致密、出现轻微的玻璃质化现象,具有很好抗酸性;陶粒样品的晶相主要为石英、钠钙长石、蓝晶石、赤铁矿和顽辉石;MgO含量过多不利于传质过程的进行,影响陶粒的致密化,所以应控制污泥原料中MgO的含量不多于3%。浸出实验表明,重金属浸出特性与不同MgO含量的陶粒的物理性质密切相关,强度高、致密性好的陶粒抗腐蚀和重金属固化能力强。

Sewage sludge and river sediment were used as raw material to produce lightweight aggregate （LWA） by a high-temperature sintering method. The main purpose of this work was to investigate the effect of MgO concentra- tion on the characteristics of LWA. The results show that when the MgO concentration was a range of 1.2% - 3%, LWA has excellent physical properties, which satisfied the requirements for the wastewater treatment filter. When the MgO concentration reached 1.5% , vitrification appeared upon the dense surfaces of LWA. Majorities of mineral phases of the sintered specimens were determined to be quartz, hematite, albite-anorthite, kyanite and enstatite with XRD. High MgO concentration is unfavorable for mass transfer, which causes compactness of the LWA de- crease. Therefore, MgO concentration should not be more than 3% in the process of making LWA. The effect of MgO concentration on leaching characteristics of the heavy metals in LWA revealed that the leaching behavior of the heavy metal is closely correlated with the physical properties of LWA. LWA with fine density, high strength, con- dense surface has high anti-corrosion ability and excellent solidification capability for heavy metals.