School of Metallurgy and Environment, Central South University, Changsha, Hunan, 410083, China.
School of Metallurgy and Environment, Central South University, Changsha, Hunan, 410083, China; Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, Changsha, Hunan, 410083, China.
J Hazard Mater. 2018 Feb 15;344:343-349. doi: 10.1016/j.jhazmat.2017.10.046. Epub 2017 Oct 23.
A new method in which Pb/Zn smelter waste containing arsenic and heavy metals (arsenic sludge), red mud and lime are utilized to prepare red mud-based cementitious material (RCM) is proposed in this study. XRD, SEM, FTIR and unconfined compressive strength (UCS) tests were employed to assess the physicochemical properties of RCM. In addition, ettringite and iron oxide-containing ettringite were used to study the hydration mechanism of RCM. The results show that the UCS of the RCM (red mud+arsenic sludge+lime) was higher than that of the binder (red mud+arsenic sludge). When the mass ratio of m (binder): m (lime) was 94:6 and then maintained 28days at ambient temperature, the UCS reached 12.05MPa. The red mud has potential cementitious characteristics, and the major source of those characteristics was the aluminium oxide. In the red mud-arsenic sludge-lime system, aluminium oxide was effectively activated by lime and gypsum to form complex hydration products. Some of the aluminium in ettringite was replaced by iron to form calcium sulfoferrite hydrate. The BCR and leaching toxicity results show that the leaching concentration was strongly dependent on the chemical speciation of arsenic and the hydration products. Therefore, the investigated red mud and arsenic sludge can be successfully utilized in cement composites to create a red mud-based cementitious material.
本研究提出了一种利用含砷和重金属的铅/锌冶炼废物（砷渣）、赤泥和石灰来制备赤泥基胶凝材料（RCM）的新方法。采用 XRD、SEM、FTIR 和无侧限抗压强度（UCS）试验来评估 RCM 的物理化学性能。此外，还利用钙矾石和含铁的钙矾石来研究 RCM 的水化机理。结果表明，RCM（赤泥+砷渣+石灰）的 UCS 高于粘结剂（赤泥+砷渣）的 UCS。当 m（粘结剂）：m（石灰）=94:6 且在环境温度下保持 28 天时，UCS 达到 12.05MPa。赤泥具有潜在的胶凝特性，其主要来源是氧化铝。在赤泥-砷渣-石灰体系中，石灰和石膏有效地激活了氧化铝，形成了复杂的水化产物。一些钙矾石中的铝被铁取代，形成了钙铁矾水化物。BCR 和浸出毒性结果表明，浸出浓度强烈依赖于砷的化学形态和水化产物。因此，所研究的赤泥和砷渣可以成功地用于水泥复合材料中，以制造赤泥基胶凝材料。
