Chemical Engineering Department, Universidad Católica del Norte, Antofagasta CP 1270709, Chile.
Construction Management Department, Universidad Católica del Norte, Antofagasta C.P. 1270709, Chile.
Int J Environ Res Public Health. 2020 Apr 3;17(7):2448. doi: 10.3390/ijerph17072448.
Copper mining, the central axis of Chile's economic development, produces a large number of tailings, which become a potential environmental risk. This study aims to evaluate the mechanical properties resulting from the making of Portland cement mixtures with tailings as aggregates so that they can be eventually used in paving stones for building inactive tailings dams. Tailings coming from two dams at a concentration plant located in Taltal (Chile) were used. Currently, Dam 1 is inactive, while Dam 2 is active. The tailings samples obtained from both dams were granulometrically characterized by sieving. In addition, pH, humidity, Eh, and mineralogical assays (sulfides, oxides, sulfates, carbonates, phosphates, and silicates) were measured. The fines content of the tailings from Dams 1 and 2 with a sieve size of N°200 ASTM were 76.2% and 29.6%, respectively. Therefore, owing to their high percentage of fines, they cannot be as used as concrete aggregates. Aggregates must contain a maximum percentage of fines so that mortars and concrete can meet Chilean standards. In this paper, to comply with a 7% and 15% fines content lower than 0.075 mm, tailings materials were mixed with conventional aggregates containing very little fines. In addition, a reference mixture was made with only tailings aggregates with and without a superplasticizer additive. To measure the mixtures of cement, aggregates, and tailings, bending and compression strength assays were made of the specimens after a 28-day curing, according to the Chilean standard. The results of the study show that the addition of only part of the tailings to the mixture increases bending strength by 26% and compression strength by 180% compared with the reference mortar, with a fines content lower than 0.075 mm in the 7% mixture, thus allowing paving stone manufacture with tailings materials. In addition, it was possible to increase the workability of the reference mixture by using superplasticizers as additives.
铜矿开采是智利经济发展的核心，它产生了大量的尾矿，这成为了一个潜在的环境风险。本研究旨在评估使用尾矿作为骨料制作波特兰水泥混合物的力学性能，以便最终将其用于建造非活性尾矿坝的铺路石。使用来自位于塔尔塔尔（智利）的一个浓缩厂的两座大坝的尾矿。目前，大坝 1 处于非活动状态，而大坝 2 处于活动状态。从两座大坝获得的尾矿样品通过筛分进行了粒度特征描述。此外，还测量了 pH 值、湿度、Eh 值以及矿物学分析（硫化物、氧化物、硫酸盐、碳酸盐、磷酸盐和硅酸盐）。大坝 1 和 2 的尾矿的 N°200 ASTM 筛分级分含量分别为 76.2%和 29.6%。因此，由于它们的细粉含量很高，不能用作混凝土骨料。骨料必须含有最大百分比的细粉，以使砂浆和混凝土符合智利标准。在本文中，为了遵守低于 0.075 毫米的 7%和 15%细粉含量，尾矿材料与含有很少细粉的常规骨料混合。此外，还制作了仅用尾矿骨料和无超塑化剂添加剂的参考混合物。为了测量水泥、骨料和尾矿的混合物，在 28 天养护后，根据智利标准对试件进行弯曲和压缩强度试验。研究结果表明，与参考砂浆相比，仅添加部分尾矿混合物可使弯曲强度提高 26%，压缩强度提高 180%，7%混合物中的细粉含量低于 0.075 毫米，从而允许使用尾矿材料制造铺路石。此外，通过使用超塑化剂作为添加剂，可以提高参考混合物的工作性能。
