# A Comprehensive Review on Mine Tailings as a Raw Material in the Alkali Activation Process
###### Abstract  
The mining industry generates vast quantities of mine tailings on an annual basis. However, due to their limited economic value, a significant portion of these tailings are deposited close to mining sites, often underwater. The principal environmental apprehensions associated with mine tailings revolve around their elevated levels of heavy metals and sulfidic minerals. The oxidation of these sulfidic minerals can lead to the formation of acid mine drainage, which in turn releases heavy metals into nearby water systems. The effective management of tailing dams requires substantial financial investments for their construction and meticulous control. Consequently, a pressing need exists for stable, sustainable, and economically viable management approaches. One promising method for addressing mine tailings is through alkali activation, a technique that serves as a stabilization process. This approach yields robust, concrete-like structures by utilizing raw materials abundant in aluminum and silicon, which conveniently constitute the primary components of mining residues. This comprehensive review outlines the research on utilizing alkali activation for mine tailings. It delves into the reactivity and chemical attributes of diverse minerals. Numerous mine tailings exhibit an inadequate level of reactivity under alkaline conditions, so various pre-treatment methodologies and their impacts on mineralogy are meticulously explored. m m e tailings; sustainability; alkali activation; mechanical activation; thermal treatment; alkaline fusion +
Footnote †: journal: Medical  
range from 97 wt% to 99 wt%) extracted from mining operations end up as mine tailings [7]. This percentage can vary depending on the type of mining, the ore being extracted, and the efficiency of the extraction process. The mentioned estimate indicates that only a tiny fraction of the original material is converted into valuable minerals. The rest, making up the majority of the material, becomes waste in the form of tailings. The estimated annual solid mine waste production is 20-35 billion tons, which includes 7-14 billion tons of mine tailings, underscoring the scale of the waste produced by mining operations worldwide [8]. The composition of mine tailings can vary widely depending on the type of ore being mined and the extraction methods used. Tailings can contain minerals, heavy metals, and processing chemicals. The size of the particles can range from fine silt to larger gravel-sized particles [9]. The Earth's crust is primarily composed of a few abundant elements like silicon, aluminum, calcium iron, sodium, and potassium, making mine tailings theoretically suitable as a raw material for construction purposes [10]. The poor reactivity of minerals within tailings can make it difficult to extract valuable components or repurpose the tailings effectively. Mine tailings often consist of minerals undergoing extensive processing during mining operations. This processing can alter the minerals' original crystalline structures and chemical compositions, making them less reactive to traditional extraction or reprocessing methods [11]. Moreover, the valuable minerals in mine tailings are usually present in low concentrations, which further compounds the challenge. Even if the minerals are reactive, their low abundance might not make extraction or recovery economically viable [12]. The fine particle size of tailings can affect their reactivity. Smaller particles can be harder to process due to issues such as agglomeration, handling difficulties, and challenges in separating minerals from one another. Furthermore, the processing chemicals used during the initial extraction can sometimes lead to changes in the mineralogy of tailings, resulting in the formation of new minerals or mineral phases that are less amenable to extraction [13]. Many mine tailings can contain high concentrations of sulfur, heavy metals, and metalloids since the valuable metals extracted from ores are frequently found within sulfidic minerals.