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With the raw materials for ironmaking are becoming increasingly complex, more accurate control of blast furnace operation is essential to reduce the energy cost and CO2 emission. CaO–SiO2–Al2O3–MgO is a basic system of ironmaking slag in which CaO and MgO are mainly come from the flux, SiO2 and Al2O3 are mainly from the raw materials. Effect of raw material composition on phase equilibrium of the slag can be described by a pseudo-ternary system (CaO + MgO)–SiO2–Al2O3 at a fixed MgO/CaO ratio of 0.2. High-temperature experiments have been carried out in this system, and the quenched samples were analyzed by an electron-probe microanalyzer. The results are presented in a pseudo-ternary phase diagram (CaO + MgO)–SiO2–Al2O3 with a fixed MgO/CaO weight ratio of 0.2. Dicalcium silicate (Ca2SiO4), Melilite (2CaO·MgO·2SiO2–2CaO·Al2O3·SiO2), spinel (MgO·Al2O3), merwinite (3CaO·MgO·2SiO2), and anorthite (CaO·Al2O3·2SiO2) are the major primary phases in the composition range investigated. A series of pseudo-binary phase diagrams have been constructed to demonstrate the applications of phase diagram on blast furnace operation. CaO-rich cordierite solid solution has been first time reported with the accurate compositions and microstructure. The liquidus temperatures and solid solution compositions are compared between the experimental data and FactSage predictions to provide useful information for optimization of the thermodynamic database.

With the raw materials for ironmaking becoming increasingly complex, more accurate phase equilibrium information on the slag is needed to refine the blast furnace operation to reduce the energy cost and CO2 emissions. CaO–SiO2–Al2O3–MgO is a basic system of ironmaking slag in which CaO and MgO mainly come from the flux, SiO2 and Al2O3 are mainly from raw materials. The effect of flux additions on the phase equilibrium of the slag can be described by a pseudo-ternary system CaO–MgO–(Al2O3+SiO2) at a fixed Al2O3/SiO2 ratio of 0.4. Liquidus temperatures and solid solutions in the CaO–MgO–Al2O3–SiO2 system with Al2O3/SiO2 weight ratio of 0.4 have been experimentally determined using high temperature equilibration and quenching techniques followed by electron probe microanalysis. Dicalcium silicate (Ca2SiO4), cordierite (2MgO·2Al2O3·5SiO2), spinel (MgO·Al2O3), merwinite (3CaO·MgO·2SiO2), anorthite (CaO·Al2O3·2SiO2), mullite (Al2O3·SiO2), periclase (MgO), melilite (2CaO·MgO·2SiO2-2CaO·Al2O3·SiO2) and forsterite (Mg2SiO4) are the major primary phases in the composition range investigated. A series of pseudo-binary phase diagrams have been constructed to demonstrate the application of the phase diagrams on blast furnace operation. Composition of the solid solutions corresponding to the liquidus have been accurately measured and will be used for the development of the thermodynamic database.

Bottom-blowing copper smelting technology was initiated and developed in China in the 1990s. Injection of oxygen-enriched high-pressure gas strongly stirs the molten bath consisting of matte and slag. Rapid reaction at relatively lower temperatures and good adaptability of the feed materials are the main advantages of this technology. Development and optimisation of bottom-blowing copper smelting technology were supported by extensive studies on the thermodynamics of the slag and the fluid dynamic of the molten bath. The history of technological development and fundamental studies related to this technology are reviewed in this paper.

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