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 28 days at ambient temperature, the UCS reached 12.05 MPa. 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.

中文翻译：

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利用赤泥和铅/锌冶炼废料合成赤泥基胶凝材料

提出了一种利用砷和重金属（砷污泥），赤泥和石灰的铅锌冶炼废料制备赤泥基胶凝材料（RCM）的新方法。用XRD，SEM，FTIR和无侧限抗压强度（UCS）测试来评估RCM的理化性质。另外，钙矾石和含氧化铁的钙矾石被用于研究RCM的水合机理。结果表明，RCM（赤泥+砷污泥+石灰）的UCS高于粘合剂（赤泥+砷污泥）的UCS。当m（粘合剂）：m（石灰）的质量比为94：6，然后在环境温度下保持28天时，UCS达到12.05 MPa。赤泥具有潜在的胶结特性，而这些特性的主要来源是氧化铝。在赤泥-砷污泥-石灰系统中，氧化铝被石灰和石膏有效地活化，从而形成复杂的水合产物。钙矾石中的一些铝被铁代替形成水合亚铁钙钙。BCR和浸出毒性结果表明，浸出浓度强烈依赖于砷和水合产物的化学形态。因此，所研究的赤泥和砷污泥可以成功地用于水泥复合材料中，以制备赤泥基胶凝材料。BCR和浸出毒性结果表明，浸出浓度强烈依赖于砷和水合产物的化学形态。因此，所研究的赤泥和砷污泥可以成功地用于水泥复合材料中，以制备赤泥基胶凝材料。BCR和浸出毒性结果表明，浸出浓度强烈依赖于砷和水合产物的化学形态。因此，所研究的赤泥和砷污泥可以成功地用于水泥复合材料中，以制备赤泥基胶凝材料。