Nitrate based salts have application as a heat transfer fluid and thermal energy storage media in solar field installations and are normally used from 200 °C up to maximum temperatures of ∼550 °C. Molten K₂CO₃-Na₂CO₃-Li₂CO₃ could potentially be used as heat transfer fluid and thermal energy storage media to replace nitrate salts due to its wider temperature operating window (400–900 °C), which improves the heat transfer efficiency. There will be improved operability and the process will be more economical viable if the lower temperature at which carbonate salts can operate could be decreased. This paper explores the melting point and high temperature stability of K₂CO₃-Na₂CO₃-Li₂CO₃ based salt mixtures, the effect of atmosphere and the effect of additives to the melt using experimental investigation and thermodynamic modeling.

Silico-ferrite of calcium and aluminum (SFCA) is one of the most commonly-produced phases in fluxed iron-ore sintering, and has long been regarded as an important bonding phase in industrial sinters. It is thus considered to have a significant effect on sinter quality. In this study, a solid solution model and database has been developed for the SFCA phase, and has been incorporated into the thermodynamic software, Multi-Phase Equilibrium (MPE). MPE calculations were compared with the in situ X-ray powder diffraction (XRD) observations of the formation of SFCA phase during sintering. The effects of the raw material composition, temperature and the oxygen partial pressure on the formation of mineral phases in the sinter, as well as the viscosity of the melt formed during sintering under equilibrium conditions, were modelled using MPE. The results show that the formation of SFCA phase can be promoted by increasing oxygen partial pressure and basicity of the raw material. Increases of Al₂O₃ and MgO content have no significant effect on the SFCA formation under equilibrium condition. The increase of oxygen partial pressure (10⁻³ atm or above) and basicity also leads to a decrease in melt viscosity, which enhances the fluidity of the melt, and hence, the assimilation of the sinter. However, increases of Al₂O₃ and MgO result in the increase of melt viscosity.

Pyrite-rich cyanide tailings (CTs) are industrial hazardous solid wastes arising from the gold mining industry. Every year, hundreds of millions of tons of cyanide tailings are produced and discharged to tailings dams. It is of great significance to dispose of cyanide tailings harmlessly and resourcefully. The feasibility of calcination of calcium sulphoaluminate (CSA) cement clinker using pyrite-rich cyanide tailings as Fe₂O₃ and SO₃ sources was investigated for this paper. The behavior of pyrite during the calcination of cyanide tailings under various calcination conditions and the properties of calcium sulphoaluminate cement clinker were examined. The results show that it is feasible to produce calcium sulphoaluminate cement clinker using pyrite-rich cyanide tailings. The optimal conditions for the calcination of calcium sulphoaluminate cement using pyrite-rich cyanide tailings are confirmed. During the calcination process, the cyanides decompose into carbonate, CO₂, and N₂. The pyrite decomposes into Fe₂O₃ and SO₂, and they react with CaO and Al₂O₃ to form the intermediates of CaSO₄, 2CaO·Fe₂O₃, and CaO·2Al₂O₃, which further react to form 3CaO·3Al₂O₃·CaSO₄, 4CaO·Al₂O₃·Fe₂O₃, and 12CaO·7Al₂O₃. The calcium sulphoaluminate cement prepared by pyrite-rich cyanide tailings exhibits excellent mechanical properties and meets the compressive strength criteria of 42.5 grade calcium sulphoaluminate cement.

The published phase diagrams of some key P ₂ O ₅ -containing systems which are relevant to the steelmaking slag and the available experimental data on phosphorus partitioning between liquid iron and slags consisting of SiO ₂ -Al ₂ O ₃ -Fe ₂ O ₃ -FeO-MnO-MgO-CaO-Na ₂ O have been reviewed and assessed. A set of data under carefully controlled experimental conditions, which was considered to be more reliable based on the assessment, was selected for optimising the generalised central atom (GCA) model parameters of phosphorus-containing slag systems. The developed model database is proved to be able to represent the liquidus temperature of some key P ₂ O ₅ -containing systems and the phosphorus distribution ratio between the steelmaking slags and liquid iron reasonably well. With the developed GCA model database, the dephosphorization reaction in the steelmaking process was modelled under various operating conditions such as slag chemistry and temperature. The results show that the phosphorus distribution ratio between the slags and liquid iron displays a maximum point with variation of the FeOx content in the slag. It also shows that the phosphorus deportment to the slag is favored by decreasing the operating temperature and MgO content, and increasing the CaO/SiO ₂ ratio in the slag. Comparison with the model of the phosphorus distribution data from a commercial BOS furnace shows that operating conditions do not permit to reach P equilibrium contents. The dis-equilibrium degree of P was found to be increased with increasing slag viscosities.