Design of Semiconductor Nanocrystals from Low Grade Iron Ore for Environmental Remediation

Abstract

India, the second-largest crude steel producer globally, possesses significant iron ore resources, mainly hematite (Fe2O3) and magnetite (Fe3O4). With iron content ranging from 25% to 45%, these deposits are ideal for efficient extraction and steel production. However, the escalating demand for iron ore, driven by the National Steel Policy 2017, depletes high-quality deposits and generates substantial quantities of iron ore tailings. Iron ore tailings, comprising 10-25% of the run of mine (R.O.M) material, are discarded during processing due to their complex mineral composition and the need for effective beneficiation methods. These tailings contain micro-fines with 48-62% Fe, along with gangue minerals like alumina and silica. Insufficient maintenance of tailings dams and the accumulation of waste minerals have led to catastrophic failures, impacting global iron ore trade and raising environmental concerns. To address this, researchers have explored alternative uses for iron ore tailings, such as adsorption processes, ceramic tile production, and synthesis of magnetite nanoparticles. Utilising tailings as an iron precursor for nanoparticle synthesis has gained significant attention due to the wide-ranging applications of these nanoparticles in electronics, medicine, and environmental remediation. This thesis focuses on a straightforward, efficient, and environmentally benign process for synthesising photocatalytic nanocomposites using iron ore tailings as an iron precursor. By repurposing waste material, the need for additional iron precursors is eliminated. This study presents a scalable method for preparing iron-based nanoparticles from waste material without requiring additional iron precursors. The synthesised nanocomposites exhibit optical, magnetic, and photocatalytic properties, enabling efficient degradation of industrial dyes. The stability and reusability of the photocatalyst are also investigated from economic and environmental perspectives.