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The crystallisation behaviour of Fe 2 O 3 during preheating and roasting of pellets made from mixed magnetite-haematite (M-H) concentrates has been studied. The results indicate that the strength of pellets is mainly provided by the crystalline connections between Fe 2 O 3 particles during preheating. This occurs because the activity of Fe 2 O 3 from secondary haematite (SH) (oxidised from magnetite concentrate, SH) is higher than from original haematite (OH). In the roasting process, when temperature is lower than 1250uC, the strength is mainly provided by the development, connection and growth of Fe 2 O 3 crystalline grains from SH. Only if the temperature exceeds 1280uC does Fe 2 O 3 recrystallisation in OH grains develop well with the iron ore particles in the pellets fully connected, so increasing pellet strength.

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This paper describes a microstructure-based uniaxial strain-controlled fatigue life prediction model applied to A319 aluminum alloy which is widely used in automobile industry. The materials made with different casting conditions are characterized and quantified in terms of secondary dendrite arm spacing (SDAS), size, and aspect ratio of eutectic Si particles. Uniaxial low cycle fatigue tests have been performed on four groups of A319 alloy under different casting conditions in which cooling rate and Sr addition are variables. It is shown that the effect of various degrees of microstructure on the fatigue life and fatigue behavior is obvious. The first part of the paper is quantitatively characterizing the microstructure of samples to identify the influence of different casting conditions. With regard to mechanic properties, the tensile properties and fatigue behavior of samples are analyzed combining with microstructure. Finally, a microstructure-based Manson-Coffin-Basquin model is proposed to predict fatigue life of Al-Si alloy.

Although great efforts have been made to decrease nutrient (notably nitrogen and phosphorus) loads and lighten related environmental damages, coastal eutrophication remains a persistent environmental crisis. To estimate whether the rapid development of the local economy has accelerated the eutrophication in Zhanjiang Bay, a newly developing industry in South China, the combination of the seasonal nutrients and other physicochemical parameters from twenty cruises during 2017-2021 and historical data (past 30 years) was analyzed in this study. The results showed that the eutrophication in the upper bay is significantly higher than that in the lower bay (more than 8 times), which is mainly related to the terrestrial input and weak hydrological conditions in the upper bay. Also, eutrophication is more severe in the rainy seasons than that in the dry seasons (nearly 2 times) because abundant nitrogen and phosphorus were brought into the bay by terrestrial discharge and river water. From a long-term perspective, dissolved inorganic nitrogen concentrations have been effectively controlled in Zhanjiang Bay, while phosphate concentration increased sharply in the past 30 years. Correspondingly, the eutrophication in Zhanjiang Bay significantly increased over the past 30 years, and the eutrophication index in the recent 5 years (2017-2021) is nearly 10 times that of the 1990s, suggesting that the increase of phosphate discharge from the increasing industrial factories around Zhanjiang Bay, rather than nitrogen discharge is the culprit causing the aggravation of eutrophication. Our study is essential to effectively implement a land-ocean integrated nitrogen and phosphorus control strategy to improve water quality and mitigate eutrophication in the bay.