Application of TiO2 nanoparticles for eco-friendly biodiesel production from waste olive oil

An environmentally benign, simple, and efficient process has been developed for biodiesel production from waste olive oil in the presence of a catalytic amount of TiO₂ nanoparticles at 120°C with a conversion of 91.2% within 4 h. The present method affords nontoxic and noncorrosive medium, high yield of biodiesel, clean reaction, and simple experimental and isolation procedures. The catalyst can be recycled by simple filtration and reused without any significant reduction in its activity.     

A new coal pillars design method in order to enhance safety of the retreat mining in room and pillar mines

Most of the proposed methods for coal pillar design determine pillar dimensions using pillar load estimation only through the tributary area theory. Designing pillar based on these methods is not appropriate in room and pillar mines with pillar recovery because retreat mining and gob creation generate abutment loads. Neglecting abutment loads in design stage may lead to pillar failure and destructive effects during retreat mining. Thus proper pillar design has a remarkable effect on mining safety. In this paper, a step-by-step method is presented to design pillars with square shape in room and pillar mines with regard to existing pillars in the active mining zone (AMZ) and estimating abutment loads according to experimental equations. A decrease in pillar failure risk during retreat mining is the most significant benefit of this method. This method has been applied to determine optimum pillar dimensions in the main panel of Tabas Central Mine (TCM), located in the mid-eastern part of Iran. Obtained results show the abutment loads account for 27% of the total loads applied on pillars in AMZ in this panel. Pillar width, based on this method, is also obtained 11.6 m.