Fabrication of Baking-free Bricks from Iron Ore Tailings

Background: Tailings produced from iron ore smelting processes have increased dramatically in recent decades. The storage of tailings not only needs high cost, but also causes a great environmental and safety hazard. Therefore, it is urgent to use new technologies to comprehensively utilize tailings. Methods: The phases and micro-morphology of the baking-free bricks were investigated by X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The optimal components and preparation parameters of the baking-free bricks were determined by controlling the ratio of the raw materials and forming pressure. The compressive strength and density of the baking-free bricks were analyzed by controlling the forming pressure and curing time. Result: The optimal components of the baking-free bricks are 65wt.% tailings, 5wt.% titanium gypsum, 17wt.% slag, 5wt.% acetylene sludge, 8wt.% waste brick powder. The optimal forming pressure is 10MPa. 28 d compressive strength and density of the baking-free bricks reach 19.8 MPa and 1622.92 kg.m-3, respectively. Irregular particles and ettringite (Aft) nanorods in the baking-free bricks contribute to the improvement of the compressive strength and compactness of the tailing bricks. Conclusion: Baking-free bricks were successfully prepared from iron ore tailings by pressure forming method and exhibited great application promising in the construction field.