Dataset on eco-friendly cement production using iron ore tailings from Brazil and evaluation of grinding process on the synthesis of geopolymers

The use of iron ore tailings in Brazil is an important topic after two recent tragedies. The data were collected in order to understand the geomechanical feasibility of eco-friendly cements using iron ore tailings and evaluate the impact of the grinding process on the compressive strength of geopolymers. The data are based on two major studies using the same methodology. The first one is the examination of the material best composition in terms of uniaxial compression resistance by varying its proportions of iron ore tailings (IOT), metakaolin (MK) and alkaline solution (composed by 1:3 ratio of sodium hydroxide (NaOH) and sodium silicate (Na2SiO3)). The second one is the evaluation of the effects in compressive strength when grinding the iron ore tailings for 1, 2 and 3 hours for producing the geopolymer. The best proportion consisted in 50% of iron ore tailings, 25% of metakaolin and 25% of a alkaline solution obtained an uniaxial compressive strength resistance of 23.5 MPa in 3 days. Also, the gain obtained with the ground tailings after 3 hours only occurs in the firsts days of cure, which does not justify grinding for this iron ore tailings due to the high cost of this operation. Tests with 1 and 2 hours of tailings grinding showed lower results of UCS when compared with IOT without milling, which is unexpected and needs further investigation to understand this behavior. One possible explanation is material agglomeration during the initial grinding times, and it is feasible that the clustering of particles limited the reaction. Finally, it appears that geopolymer mortars seem to be a viable alternative for the sustainable use of IOT in the state of Minas Gerais, in Brazil, since they present satisfactory results of compressive strength.

巴西铁矿尾矿（iron ore tailings, IOT）的资源化利用是近期两起重大安全事故后备受关注的重要议题。本数据集旨在探明利用铁矿尾矿制备环保胶凝材料的岩土力学可行性，并探究粉磨工艺对地质聚合物抗压强度的影响。本数据源自两项采用统一试验方法的核心研究。
第一项研究通过调整铁矿尾矿、偏高岭土（metakaolin, MK）与碱性激发剂（由1:3比例的氢氧化钠（sodium hydroxide, NaOH）和硅酸钠（sodium silicate, Na₂SiO₃）复配而成）的掺配比例，探究最优物料配比以获得最佳单轴抗压强度。第二项研究则考察了铁矿尾矿分别经1、2、3小时粉磨后，对所制备地质聚合物抗压强度的影响。
试验结果表明：当铁矿尾矿掺量为50%、偏高岭土掺量为25%、碱性激发剂掺量为25%时，试样在养护3天后的单轴抗压强度可达23.5 MPa。此外，经3小时粉磨的尾矿制备的试样，其强度增益仅体现在养护初期，考虑到粉磨工艺的高成本，该处理方式并不具备经济可行性。针对粉磨1小时与2小时的尾矿试样，其单轴抗压强度（uniaxial compressive strength, UCS）反而低于未粉磨的铁矿尾矿试样，该结果超出预期，需进一步开展研究以阐明其作用机制。一种可行的解释是：初始粉磨阶段物料发生团聚，颗粒团聚体限制了碱激发反应的进行。最后研究表明，地质聚合物砂浆可作为巴西米纳斯吉拉斯州铁矿尾矿可持续资源化利用的可行方案，其抗压强度表现满足工程应用要求。