Physicochemical Characteristics of Silicomanganese Slag as a Recycling Construction Material: An Overview

Silicomanganese (SiMn) slag is a by-product of ferromanganese and SiMn alloy production poses significant challenges in terms of environmentally sound disposal given its substantial volume. This brief review aims to assess the physicochemical attributes of SiMn slag and explore its potential applications in construction materials recycling. To accomplish this, we systematically evaluated 20 relevant articles, categorizing them into segments covering reutilization methods, key considerations, enhancement strategies, and the recent challenges and prospects associated with SiMn slag reutilization. Our analysis encompassed SiMn slags from five countries, revealing consistent chemical compositions characterized by SiO₂, Al₂O₃, CaO, MnO, MgO, FeO + Fe₂O₃, and K₂O + Na₂O at similar proportions. We identified two distinct types of SiMn slag, i.e., air-cooled and water-quenched, each possessing unique physical properties influencing their suitability for reutilization. SiMn slag has been successfully repurposed into various construction materials, including cement paste, mortar, concrete, alkali-activated matrices, bricks, backfill materials, Mn extracts, and binder/cement. Several critical factors must be considered when reutilizing SiMn slag in construction materials, including cooling methods, moisture content, particle size (fineness), equipment, energy requirements, and cost considerations. To enhance the reutilization process, we propose a structured approach consisting of four key steps, i.e., incoming waste assessment, pre-treatment, physical/chemical treatment, and product development. Furthermore, this review suggests several avenues for future research, including the development of industrial-scale recycling applications, exploring environmentally friendly landfilling methods for SiMn slag, and assessing the practicality and feasibility of SiMn-slag-based products in real-world construction projects.