Reuse of iron tailings powder as concrete mineral admixture

With the continuous development of mineral resources, a large amount of solid waste is formed after mineral processing, and tailings are one of the most abundant solid wastes. The accumulation of tailings in tailings ponds not only pollutes groundwater and the surrounding environment, but also threatens the safety of surrounding people and buildings.

The main use of tailings is to prepare fillers and building materials. In particular, coarse iron tailings can be used as aggregates to prepare fillers and concrete. Iron tailings can be used as a machine-made aggregate with good performance in filling materials and concrete. Part of the tailings is used to prepare pillar concrete; through fiber reinforcement, the concrete has good mechanical properties. However, with the continuous development of mineral processing technology, the tailings are getting finer and finer, and the fine tailings below 75 μm can reach more than 80%. Fine-grade tailings will lead to an increase in cementitious substances in the filling materials and cannot be used as concrete fine aggregate, which greatly increases the difficulty of utilizing the tailings. Fine-grained tailings require grading treatment, and a large amount of fine-grained tailings cannot be utilized, resulting in considerable waste of resources, reducing the comprehensive utilization rate of the tailings, and increasing processing costs.

On the other hand, infrastructure construction consumes large amounts of concrete. The production and preparation of concrete results in shortages of many resources, especially high-quality mineral admixtures. Mineral admixtures are essential raw materials for modern green high-performance concrete. In the context of low-carbon environmental protection, more and more admixtures will replace cement in concrete, which will help reduce carbon emissions and form an environmentally friendly cementitious material system. In some areas, high-quality mineral admixtures such as fly ash and slag powder are scarce. Therefore, it is imperative to rationally and efficiently utilize various resources, especially waste resources.

In order to supplement the shortage of traditional admixture resources such as fly ash and slag and expand the utilization of industrial solid waste, the reuse as concrete mineral admixtures should be considered. The content of fine powder below 75 μm in iron tailings continues to increase. Because iron tailings powder is mainly composed of SiO2, Al2O3 and other chemical components, it can be used as a concrete admixture. At present, the research on iron tailings powder as a mineral admixture in concrete mainly focuses on the influence of iron tailings powder on the strength of concrete, as well as the activation and hydration of iron tailings powder

Research shows that after iron tailings powder and slag powder are mixed, concrete has better mechanical properties and its hydration rate is very slow, which can effectively reduce the hydration heat of concrete. BS. Research has found that the fineness of iron tailings powder has an important impact on the performance of concrete. Some scholars believe that iron tailings powder can promote the performance of concrete through effective activation and further grinding. By studying the impact of iron tailings powder as a concrete admixture on the mechanical properties and microstructure, it was found that iron tailings powder can be used as a mineral admixture to prepare concrete materials. However, as an inactive mineral additive for concrete, iron tailings powder needs to be mixed with highly active slag powder to form a composite additive. The influence of iron tailings powder and slag powder on the strength of concrete, especially the development of long-age strength, needs to be explored urgently.