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During the roasting of stone coal, a sintering phenomenon usually occurs, which is related to the chemical composition of the stone coal. In this study, the sintering beginning temperature (SBT) and ash fusion temperatures (AFTs) of stone coal with different CaO, Fe 2 O 3 , SiO 2 and Al 2 O 3 content were investigated. FactSage has been used to calculate the phase distribution of roasted stone coal, to analyze how these components influence the sintering behavior during roasting. For stone coal with low CaO content, CaO reacted with albite, leucite, and quartz to generate an amorphous phase, which would easily cause sintering, while for stone coal with high CaO content, CaO took part in the formation of andradite and Na 2 Ca 3 Si 6 O 16 . Most Fe 2 O 3 in roasted stone coal stably existed as hematite in the system and did not react with others, which had almost no effect on sintering. SiO 2 and Al 2 O 3 in the stone coal contributed to hinder the formation of amorphous phases, especially for high Al 2 O 3 stone coal, in which mullite was generated.

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The present study aimed to understand the effect of venous valve lesion on the valve cycle. A modified immersed finite element method was used to model the blood–tissue interactions in the pathological vein. The contact process between leaflets or between leaflet and sinus was evaluated using an adhesive contact method. The venous valve modeling was validated by comparing the results of the healthy valve with those of experiments and other simulations. Four valve lesions induced by the abnormal elasticity variation were considered for the unhealthy valve: fibrosis, atrophy, incomplete fibrosis, and incomplete atrophy. The opening orifice area was inversely proportional to the structural stiffness of the valve, while the transvalvular flow velocity was proportional to the structural stiffness of the valve. The stiffening of the fibrotic leaflet led to a decrease in the orifice area and a stronger jet. The leaflet and blood wall shear stress (WSS) in fibrosis was the highest. The softening of the atrophic leaflet resulted in overly soft behavior. The venous incompetence and reflux were observed in atrophy. Also, the atrophic leaflet in incomplete atrophy exhibited weak resistance to the hemodynamic action, and the valve was reluctant to be closed owing to the large rotation of the healthy leaflet. Low blood WSS and maximum leaflet WSS existed in all the cases. A less biologically favorable condition was found especially in the fibrotic leaflet, involving a higher mechanical cost. This study provided an insight into the venous valve lesion, which might help understand the valve mechanism of the diseased vein. These findings will be more useful when the biology is also understood. Thus, more biological studies are needed.