A series of thermodynamic calculations are performed for the roasting of pyrite in changing temperatures and atmospheres. The relationship between Δ_rG^θ and temperature in the range of T = 300–1200 K shows that, depending on the atmosphere it is in, reactions of pyrolysis, oxidation or reduction can occur. Both the pyrolysis of pyrite in an inert atmosphere and its oxidation by oxygen can form pyrrhotite (mainly Fe_0.875S and FeS), but the temperature required for oxidation is much lower than that for pyrolysis. In an oxygen-containing atmosphere, the isothermal predominance areas for the Fe–S–O system indicate that a change in temperature and oxygen partial pressure can lead the pyrite to undergo desulphurization to pyrrhotite (FeS₂ → Fe_0.875S/FeS) or iron oxides (FeS₂ → Fe₃O₄/Fe₂O₃), or sulphation to iron sulphates (FeS₂ → FeSO₄/Fe₂(SO₄)₃). The presence of carbon is beneficial to the desulphurization of pyrite under an oxidizing atmosphere since iron sulphates can be converted to iron oxides at very low levels of P_CO/P_CO2. Results presented in this paper offer theoretical guidance for the optimization of roasting of pyrite for different purposes.

In recent years, many rivers, lakes and oceans around the world have exposed to diverse contaminants or red tides due to excessive discharge of nutrients such as nitrogen and phosphorus. The high content of phosphorus often leads to the nutrition of water body. Water resources have been seriously threatened, which has brought great impact on environment and public health. Therefore, the removal of phosphorus from wastewater attracts more and more attention. This work reviewed the forms, hazards and treatment of phosphorus in wastewater, and focuses on the methods of phosphorus-containing wastewater such as chemical precipitation, adsorption, ion exchange, membrane separation and biological methods. With the current economic and development of world, the bio-treatment of phosphorus-containing wastewater will become a research trend in the future, and the research and development of new technologies for phosphorus-containing wastewater will be an important topic for the treatment of phosphorus-containing wastewater in the future.